I will be updating this article regularly now it is live on the Mini Spares website and re-arranging my findings. As so many misleading articles and claims of rarity seem to crop up about the A series heads I have decided to add my own findings, starting from when I first began unbolting parts and changing cylinder heads at H.A Saunders an Austin/Morris main dealership where I started work in 1963, coincidently the same year that William Morris (Lord Nuffield) died, who was the founder of Morris Motor Co, Morris Garages and left his legacy of MG, Morris and Wolseley with the name MOWOG on parts and packaging, plus the 1071cc Cooper S and much (XSP) experimental engine work. BMC seemed to always have strikes or unrest during the 1960’s causing the assembly lines to go through traumas with Leyland taking over in January 1968 with top personal changes, causing Austin and Morris to eventually alienate each other allowing unscheduled parts and oddities to be fitted to get vehicles built for sale. Sorry this article became a thesis but try to read it all to understand the differences and changes as most of this is from memory or notes from years ago which I have since reliably checked, plus what I know or have found out to date. If you buy a bare head without valves, top caps and cotters remember the caps and cotters alone can cost over £60 for a set let alone the cost of valves, so beware unless you have a like for like head with all usable parts. Also give a thought to any engineering costs on what you are buying as fitting exhaust valve inserts to run your car on current unleaded petrol will significantly add to the over inflated price many vendors are trying to achieve.
Casting number | Inlet | Exhaust | CC | Normal Application | |
2A628-No such casting.———— 21086 is correct | 1.0625” 26.99mm | 1.000” 25.4mm | 24.5cc | Austin A30 & Morris Minor series 2(803cc) | Note 1 Note 2 |
2A629 | 1.0625” 26.99mm | 1.000” 25.4mm | 24.5cc | 850, 998cc Mini 948cc inline | Note 2 |
12A1456 | 1.0625” 26.99mm | 1.000” 25.4mm | 24.5cc | 848, 998cc Mini Sprite/Midget 948cc | Note 3 |
2A609 Authi | 1.0625″ 26.99mm | 1.000″ 25.4mm | 24.5cc | Authi Mini 850cc & 998cc | Note 4 |
CAM4810 | 1.0625” 26.99mm | 1.000” 25.4mm | 25.5cc | 998 Metro &Mini A plus, 1980 on and 89 on lead free- | Note 5 |
CAM4004 | 1.0625″ 26.99mm | 1.000 25.4mm | 25.4cc | 998cc air injection ports | Note 6 |
12A185 | 1.156” 29.36mm | 1.000” 25.4mm | 24.5cc & 26.1cc | 997 Cooper Sprite/Midget early 9 stud, | Note 7 |
12G202 | 1.156” 29.36mm | 1.000” 25.4mm | 26.1cc | 997 Cooper, all 1100cc square inlet ports | Note 8 |
12G201 Authi | 1.156″ 29.36mm | 1.000″ 25.4mm | 24.7cc | innocenti/Authi ADO16 1098cc | Note 9 |
12G206 | 1.156” 29.36mm | 1.000” 25.4mm | 28.4cc | Sprite 10CG engine & few early MG1100/Cooper 998 | Note10 |
12G295 | 1.218” 30.93mm | 1.000” 25.4mm | 28.3cc | 998 Cooper, MG1100 locating ring insets | Note11 |
12A185/AEA626 | 1.401” 35.6mm | 1.22” 31mm | 21.4cc | MKI 1071 Cooper S 1963 | Note12 |
AEG163 | 1.401” 35.6mm | 1.22″ 31mm | 21.4cc | 1071/970/1275 Cooper ‘S’ | Note13 |
AEG305 | 1.401” 35.6mm | 1.22” 31mm | 21.4cc | 1964 Formula 3 1000cc | Note14 |
12G940 | 1.3125” 33.3mm | 1.156” 29.2mm | 21.4cc | 1300, 1275GT & all A+ & Turbo | Note15 |
2G93 NMQ 12G939? Spain | 33.3mm 35.6mm | 29.2 | 21.4cc | 1275 Authi Spain | Note16 |
12G1316 | 1.3125″ 33.3mm | 1.156″ 29.2mm | 21.4cc | Air injection ports, 1275cc | Note17 |
12G1805 | 1.401” 35.6mm | 1.156” 29.2mm | 21.4cc | MG1300, 1300GT, Cooper ‘S’ MK3 | Note18 |
12G940 | 1.401” 35.6mm | 1.156” 29.2mm | 21.4cc | A Plus MG Metro / Vanden Plas HC 9 stud only | Note19 |
12G940B | 1.3125″ 33.3mm | 1.156″ 29.2mm | 21.4cc | Mini 1991 on HIF38 and SPI | Note20 |
LDF105800 | 1.3125” 33.3mm | 1.156” 29.2mm | 21.4cc | Multipoint injection | Note21 |
C-AHT347 | 1.406″ 35.7mm | 1.161″ 29.5mm | 21.4cc | Mini Spares Alloy Head | Note22 |
8 Port and XSP 2A185 etc | Plus all Experimental Heads | Note23 | |||
CC = Original Combustion Chamber Size |
Since the manufacture of the first A series heads was nearly 70 years ago not many early engines or owners are original, many having head swops, refacing or valve changes along with other irregularities found but the following article shows the original characteristics.
Cylinder heads with MOWOG cast in them were originally destined for machining at Morris Engines, part of Morris Garages, Court House Green, Coventry who had their own original Special Tuning Dept which originated in 1957 as Morris Engines were supplying power units for the old MG and new Sprite builds at Abingdon. There was also a BMC competitions dept already at Abingdon from Dec 1954 but the famous BMC ST Dept that we all remember started at Abingdon in the early 60’s and in 1964 started selling their parts under the leadership of Basil Wales until 1974 when it was rebranded Leyland ST and finally closing the doors in the early 80″s .
Eddie Maher was Morris Engines chief experimental engineer and brains behind getting increased power and changes to the engines design and with Downton’s Daniel Richmond getting involved with him on cylinder head flow designs to the original 1943 patented head designs by Harry Weslake, there was no holding back major development. Daniel Richmond then worked closely with Issigonis at the Longbridge site from the early 1960’s and as far as we know Daniel was responsible for the 1275cc 12G940 casting and port shapes which were similar design to the 12G295 although for totally different fitment uses. Morris garages had owned Wellingborough Foundry from 1947 who were acclaimed as being one of the finest casting companies in the UK and most of their early heads had MOWOG cast on them along with Wellingborough Foundry’s own casting mark, a Capital W in a rhombus shaped triangle. Morris Engines foundry, used a Capital M in a rhombus shaped triangle and along with Wellingborough Foundry were the only combined companies to make a version of every model “pre A series head” until they closed about 1981 with most of Wellingborough’s work transferred to Beans Industries @ Tipton who had been a subsidiary of British leyland since 1968 and owned Wellingborough from 1969 on. Beans Industries casting mark was a capital B leaning to to the right in a circle or the letters BIL. Apart from the previous two, many heads came from Sterling Metals (SM), Midland Motor Cylinders (MC), C&B Smith Ltd (CBS in a circle) who by 1965 became GKN Forgings and Castings which during early 1980’s then became part of Birmid Qualcast group. Also heads were cast at West Yorkshire Foundry, Leeds. See end of article for foundries and brief history.
Large bore heads are a classification for all Cooper S variants, 970, 1071 and every 1275cc which all started with 2.780″ (70.6mm) piston bore size.
Small bore heads are 803cc, 850cc, 948cc, 997cc, 998cc,1098cc with any original standard bore size up to 2.54″(64.57mm). All small bore only ever had old imperial 1”(25.4mm) wide exhaust valves. Basically, never fit a small bore head to a large bore engine and fitting a large bore head to a Small bore engine is not always advisable for road use and requires a lot of work, knowledge and modifications. Small bore heads had the rocker oil feed plug on the bottom of the head whereas large bore heads except very early 1071 Cooper S had the rocker oil feed plug at the top. Originally they used a brass plug as shown on the red head below but on A plus about 1984 they used a rivet and a very large rivet from 1991 on as shown on extreme right

A plus small bore on left with oil gallery rivet for rockers feed on bottom of head and then most large bore heads with oil gallery on the top of the head using a plug and then from about April 1989 onwards-large headed rivets.
Most casting numbers are viewed by looking on the top of the head with the spark plug holes in front of you, with a few numbers upside down or sideways. The last of 12G202, 12A1456, 12G940 heads made from the very late 1970’s could have the number cast at the back of the thermostat. The 12G940B started with SPI from 1991 and LDF105800 for MPI from 1996 both have the numbers cast on the end of the head by the exhaust manifold tube and the old heater valve location. All reference numbering starts from number one piston bore, the thermostat end -1st to 4th rocker pedestal, 1st to 8th valve and 1st to 8th push rod hole. The easiest way to tell the difference between small bore and large bore heads is by looking at the thermostat stud positions and the heater tap angles. All large bore, Cooper S and 12G940 have the 2 front thermostat studs level with front head studs whereas the small bore 850cc to 1098cc have only one stud at the front. Heater tap holes are at 90 degree angle on small bore heads and 45 degrees angle on large bore heads.


At least 14 million A series heads were made with slight variations to fit Mini, Metro, all the range of 1100/1300, Allegro, Austin A30/A35/A40 Farina, Morris Minor, Austin Healey Sprite and MG Midget, Marina, Maestro, Ital Montego, using one of the following power units, 803cc, 848cc, 948cc, 997cc, 998cc, 1098cc, 970cc, 1071cc and a majority being 1275cc. Every head in the last few years appears for sale fairly regular, so no head is particularly rare apart from very rare large bore 11 stud head AEG220, AEG305, next the 12A185/AEA626 and then AEG163, all “S” type heads. Prices for second hand heads, even bare heads in poor condition have risen as vendors try their luck.
PS-although the Mini had special editions known as Sprites, namely 1983/4 with 998cc engine and 1992 with 1275 engine, we refer to Sprite/Midget as the 2 seater sports car from 1958-74 on our application list.
All castings are liable to have many core and reference markings, let alone rivet and screw head marks that are of little consequence or meaning to anybody now apart from maybe the date stamping which is dealt with near the end of the articles, but using the reference chart the following are the main casting numbers characteristics to look for. Small bore heads with a recessed or sculptured manifold face were the earliest type with clips on the valve collets which had deep square cut collet grooves. The Cooper S until fitment of 12G940 castings also had recessed or half sculptured backs, but every 12G940 produced from 1966 had a flat manifold face and some other head types were gradually phased in with flat manifold face from late 1967 to 68 similar to all 12G940 castings. The valves with small single semi circular cotter grooves 88G459 as fitted to all large bore heads to 1983/4 were also gradually phased in from 1969-73 across most of the A series small bore range, with Mini being the last. The last generation of 12G202, 12A1456 and A Plus 12G940 had flat machined strengthening lugs behind the middle 3 of the front 5 head studs which can only be seen when rocker cover is off, this was a feature earlier heads did not have. Remember: All SMALL BORE had 25.4mm (1.00”) exhaust valves, All LARGE BORE, Cooper S Mk1/2 and AEG163 had 1.22″ (31mm) and all 12G940 heads had 1.156″(29mm)exhaust valves.
Note 1. THE MISREAD 2A628- 1.0625”inlet and round inlet port. The 2A628 head never existed but was misread and started life in David Vizards Book “How to modify Your Mini” in the 1970’s. This section is primarily written to prove there was no such casting as 2A628 and show all the earlier versions which are all similar in valve sizes etc and will all interchange 850/998cc transverse mini and inline 803cc & 948cc.

A) was a 1953 head. B)was August 1955 head. C) was a December 1957 head. c) was a 1959 head
The first A series heads appeared in 1951 with the 803cc, Austin A30 and the Morris Minor Series 2 in 1952, all without a temp transmitter hole. Originally with 1.005′(25.53mm) exhaust valve, 1.0625 (26.99mm) inlet
(A) The first versions of this head above (1951-3) only had 2A3/AF2/AS3 or 2A3/AF1/AS3 upside down between 3 and 4 rocker posts with no other markings apart from date between rocker post 1 and 2 (December 1954) or 2AC/AF1/AS3 with none using the later 2A629 casting numbers. AS3 was the code name for the new small 803cc engine being developed in the late 40’s way before the merger with Morris in 1952 and made at the Longbridge North works where it became known as the “A” series engine. AS3 was also used as a chassis number in 1952 for the new Austin A30. The 2A represented the engine number on the A30 whereas the later engine numbers we are more familiar with, start with an 8 for 850cc Mini and 9 as a prefix as on A35 in 1956, Coopers 1961 etc.
B)2A3 AF1 AS3 with MOWOG was 1954/5 but somebody has erased most of the 2A3 on this head but I have seen correct markings on A30 and early Morris Minor series 2 heads. AF1 was probably Austin Foundry or Austin Factory No 1. 2A3/AF1/AS3 is between 3rd and 4th rocker posts and MOWOG between 2nd and 3rd rocker posts.
(C) BMC stopped using the 2A prefix by leaving just AF2/AS3 between 3&4 rocker posts the correct way up but added MOWOG above 2A629 between 2&3 rocker posts. The 2A was used in the 2A629 part number but I have no idea where the 629 originated from. MOWOG originally being aligned to Morris and Cowley origin, but suppliers were shared from mid 1950’s with Longbridge. Pre production Sprite Mk1 Frogeye also, 1957 on.
(D) The fact is, there was only ever a 2A629 but the casting numbers on the right hand photo shows that if cast poorly or covered in oil it could easily have been misread as 2A628. The 2A628 might well have been the original drawing number as it was usually one number less but I have no proof as most drawing records were lost or destroyed many years ago.

2A3 between 1 and 2 rocker posts, Mowog between 2 and 3 rocker posts with SM for Sterling Metals between 3 and 4 rocker posts, fitted to 1955 A30. So Longbridge were buying in heads at this early stage

21086 is also a 2A629 design cast by Midland Motor Cylinders for Morris Engines for the 803cc Morris Minor Series 2. This head however was off a 1959 Austin A40 Farina, so castings might well have been shared by Austin and Morris factories.

Same 21086 head but with 2A629 added between 3 and 4 rocker posts MOWOG between 2 and 3 rocker posts RMC21086 between 1 and 2 rocker posts for Midland Motor Cylinders and all viewed from all upside down when looked at from spark plugs at front. A later edition of a 21086 . All of the heads above are pre runners and same spec to 2A629 and usable alternatives.
See Note 2 below for the main 2A629 history .

Note 2. 2A629- 1.0625″inlet and round inlet port, all with recessed manifold face, and less a temperature transmitter hole. Morris Engines emblem between 3 and 4 rocker posts
Read Note 1 for earlier history.
From 1956 on 948cc inline engines A35/A40 Farina, Mk1 Sprite and Morris Minor all used this head except the 948cc Sprite Mk2/Midget MK1 which used a 12A1456 which had a temperature transmitter hole. The 2A629 was fitted to the Mini 1959 to 1968 and basic 850cc a bit longer but the factory used a 12A408 thermostat housing to hold a temperature transmitter for the Mini Deluxe versions, plus Elf and Hornet which all had a temperature gauge fitted in a 3 clock binnacle. Mini production stopped at Cowley in 1968. It seems that some Longbridge cars from 1968 may have used a 12A1456 head with recessed manifold face before changing to flat manifold face late 1972. I have seen the last of MK2 cars with 99H159A engine numbers with sculptured (recessed) manifold faces. Large groove valves with cotters held in by circlips were fitted until 1973. After Longbridge’s took over mini production they sent out a technical bulletin memo early 1970’s stating the circlips 2A12 were no longer required and not necessary.


Green arrows show the 2 smaller waterway holes which were enlarged on later heads as the technical designers were always looking to make improvements. Same as Picture B
MOWOG cast above 2A629 between 2&3 rocker posts, AF2/AS3 between 3&4 rocker posts. First head with 2A629 as described under the 2A628 description from Longbridge. The head face with a row of 5 waterways had smaller holes on 2 and 4. Fitted to inline engine A35 1957.

All 2A629 had a recessed or sculptured manifold back face and round inlet ports. Early head casting from Morris Engines foundry Coventry but looks like W in a triangle this way up.
MOWOG over 2A629 between 2&3 rocker posts and with the M in a triangle upside down between 3&4 rocker posts from the Morris Engines Foundry as shown on the picture heading this article. The head shown is from a A30 and the row with 5 waterways had smaller holes on 2 and 4. I have also seen some without the M symbol that have 2.8085″ 71.336mm head thickness when the std height was 2.75″ 69.85mm. The metal thickness of the head gasket face was increased 1960/1 to overcome head gasket failures mainly encountered during Sprite Mk1 racing but the head depth was retained at 2.75.

2A629 from Wellingborough Foundry but with W correct way up as per pattern equipment below.
Looks like the same pattern equipment company were used as the head pictured above this from Morris foundry has the M symbol, but this is replaced with a W for Wellingborough. The casting part numbers were always put same way up as the foundry symbol whereas other markings which were screwed on could be anyway up. Pattern making equipment for this head below was probably by G Perry & sons, Hall Lane, Leicester who on their 1950 advert stated they had made wood and metal patterns for 65 years.

Wellingborough pattern equipment for 2A629-photo courtesy of Jon Bolton.

Above has MOWOG correct way up but can be either way up as per picture shown in Note 1.
2A629 Casting number between 1&2 rocker posts and RMC 21086 between 3rd and 4th posts both upside down. MOWOG correct way up between 2&3 rocker posts cast by Midland Motor Cylinders.

The most common head fitted from 1959 on, to 850cc Mini, inline engines 948cc Mk1 Sprite A40 Farina & Morris Minor etc
The next and last generation heads had 2A629 over SM between 3&4 rocker posts and MOWOG between 2&3 rocker posts, less all the other numbers. The most frequently available head fitting everything from Frogeye Sprite to Morris Minor 998cc and Mini to 1968 that I have noted. I have at least 10 of these and probably fitted from 1959 to 1968 at least. SM standing for Sterling Metals. Many have been replaced with the next head 12A1456 containing a temperature transmitter hole. See Note 3.
Note 3. 12A1456- 1.0625”inlet and round inlet port, with Temperature Transmitter hole. MG/Sprite 948cc 1961-3 (16,000+models) that Morris Engines supplied for the Abingdon built cars plus Non Cooper Mini from 1967/8 on . MK2 mini from 1967 might well have had these heads fitted but supply issues in December 1967 when BLMC became Leyland January 68 anything could have been fitted to get cars into the showrooms as sales were fading. I have seen an original March 68 Morris 998cc MK2 with 2A629 fitted. Fitted on 998cc Mini until A plus heads started, 1980 approx.

12A1456 with SM underneath for Sterling Metals foundry, with recessed manifold face and no other markings, basically the same as 2A629 but with slightly changed waterways allowing a hole at front for temperature transmitter. Early type cotters and clips, recessed manifold face machined at Longbridge.

Combustion chamber shape stayed the same shape for all small bore 803,850,948,998cc engines except Cooper 998cc. (997 and 1098 shared a slightly different shape owing to larger inlet valve)

12A1456 over SM between 3&4 rocker posts but with MOWOG between 2&3 rocker posts. Early circlip cotters and valves with recessed manifold face. A rare December 1967 head and I have found none earlier on Mini, most are 1968 on. This was from a Riley Elf probably at changeover point from 2A629 or for pre launch mini.

MOWOG over 12A1456 between 2&3 rocker posts and Morris Engines motif between 3&4 rocker posts, Early valves with recessed manifold face. 1969 head and fitted up to 1971/2 until replaced by flat manifold face. Also seen cast as MOWOG over 12A1456 between 2&3 rocker posts but less the Morris Motors symbol between 3&4 rocker posts,

1970’s head from Morris Engines foundry, exact same markings as rust covered head pictured above but this has a flat manifold face, usually 1971/2 on. This is a 1970 export head however.

2M2 denotes 2nd December 1972 cast head. This head is about when they started the 3 extra lugs behind the 5 front head studs. See the Ferrous Casting article at the very end of this article for clues on date stampings.
12A1456 between 2&3 rocker posts and the Morris Engines foundry symbol moved to behind thermostat housing close to where they originally stamped the first S heads. 3 front centre lug reinforcements and a flat manifold face first appeared from 1971/2 on and changeover started on the valves with smaller collet groove using 88G459 cotters.

12A1456 number cast behind thermostat housing pictured above -with extra 3 front centre head stud lug reinforcements and no other markings, with a flat manifold face, from 1971/2. This is from a 1976 car. Not sure who cast this head, probably Beans as the part number has moved to above the thermostat for Longbridge. See the previous picture for the Morris Engines head also with strengthening lugs.———

12A1456 with J5058 under date stamp from West Yorkshire foundry 1972 12A1456 between 3&4 rocker posts and J5058 between 2&3 rocker posts (some look like J6058)with flat manifold back, later small collet valves. Most castings had good port shape and valve seat positions which were favoured by engine tuners for 1000cc Autocross regulations. West Yorkshire Foundry octagon motif between 1&2 rocker posts. This foundry produced alloy precision heads for Jaguar XK120 and Jag experimental.


12A1456 with CBS insignia from the Wednesbury Wolverhampton foundry owned by GKN. The 3G4 in centre refers to the date 3/7/74.-All I have seen are dated 1973/74/75 heads.
12A1456 casting number between 3 and 4 rocker posts, flat manifold back face and late valves and cotters mainly 1973-5 on for many 850/998cc plus Mini Clubman 998 to 1975 when 1100cc was introduced except for Autos. The 12A part of the number is obliterated by a casting mark on some, as above. The CBS emblem is in small circle between 1&2 rocker posts. C&B Smith (CBS) became part of GKN forging and castings in 1965 which in the early 1980’s then became Birmid Qualcast. CBS name used late 60’s on.

FIG A Probably a Beans head machined at Longbridge.Date stamp 10H6 is 10th August 1976

(B) Pictured above, 12A1456 upside down compared to Fig A, is also cast sideways after 4th rocker post by the 8th push rod hole, and has flat back manifold face, with extra 3 front centre head stud lug reinforcements from late1973. On the later casting Fig A or Fig C the number is upside down compared to FIG B shown from heater tap end.
(C) On this later casting the number is moved closer to the push rod holes so only reads 12A14 or 12A145, often with a B by No1 valve but this is not the Beans emblem, with extra 3 front centre head stud machined lug reinforcements from October 1973 to Mid 1977, C is a 1977 head. I believed these to be Beans heads, but still trying to confirm whether any heads were cast by Longbridge at this time who machined them.
Note 4. 2A609 Authi Mini 1.0625″ inlet and round port inlet

A) Similar to early 12A1456 with thermal transmitter hole and early recessed manifold face but later type small groove cotters and valves this was fitted to Authi 850/998cc minis from 1969/70 to circa 1975 made in Los Corrales De Beulna near Santander, Spain by NMQ until its closure. The BL insignia was probably used on the part number rather than NMG as per the 1275cc because Authi became 51% owned by BLMC in 1969.
B) There was also an ALLOY head cast 2A609 by Barwell for Derrington with small bore valve centres and also one for large bore valve centres but with 11 bolt holes and 2A609 on both by the 1st valve spring. Both had 1275 large bore angled thermostats and started with 997 valves, but larger valve sizes used on later heads as they updated them. I have seen a few in the UK plus (Calver ST on facebook) Mark Forster’s (MK1 mini forum) and in the USA, a head can be viewed on the Mini Mania website. I have only included this alloy head as it had a relevant part number to A series heads but had an unusual combustion chamber shape.

Derrington on left segment and Barwell on right above patent number

No combustion chamber peaks on Derrington Barwell head
Note 5. CAM4810 A plus, 1.0625”inlet and round inlet port.
Used on Allegro 1980-82, Metro 1980-90, Mini 1981-1992 . Valves with single collet groove 88G459 were phased out by 1983. Later A Plus valves from 1984/5 had 3 collet grooves and the collets CAM6975 had twin grooves with a 14 degree cone taper instead of the 10 degree taper as used on Pre A Plus single groove collets. The A Plus new spring caps have a raised ridge around the collet hole.
All the CAM4810 A Plus 998cc heads had flat manifold face and later post 1981/2 Beans heads had the extra machined lugs on the back of the 3 front middle head studs. I believe all Beans or heads machined at Longbridge for the assembly line were yellow with smaller water jackets probably to stop valve seat cracking, although over heating never seemed a real problem. Albeit, we have many of these heads returned from our reconditioners as not serviceable. Introduced from 1980 at Longbridge, with Wellingborough Foundry closing in 1981 and their production transferred to Beans Industries at Tipton. Morris Engines at Courthouse Green then subsequently closing by 1982. Some early heads without the 3 front stud strengthening lugs were cast at West Yorkshire Foundry Leeds, of which some were green or black.

Wellingborough logo between 3&4 rocker posts and a different casting below
CAM4810 between 2&3 rocker posts high under 4&5 push rod holes with W symbol between 3 and 4 rocker posts and no lugs on front stud posts was the last heads from Wellingborough Foundry 1980-1 mainly for the Metro pre production or early cars with by pass hose blanked off.

Last of the Wellingborough logos before its closure in 1981, logo between 3&4 rocker posts and with part number lower in centre, than the head shown above, showing 2 different castings.

Three green arrows denote the smaller holes about .500″ (1/2″) average whereas the larger holes are 0.625″(5/8″) average as per drawings in old British imperial sizes but do fluctuate. This photo is of our used C-AHT88 large valve conversion on a CAM4810.

CAM4810 between 3&4 rocker posts, J5181 and date stamp between 2&3 rocker posts and the Leyland roundel Motif which was designed in 1968 with L in the middle, prominent between 1&2 posts with West Yorkshire foundry logo underneath with the Y superimposed over the W with the F also incorporated in the bottom of the Y. Most of their work had dried up by 1982 when Austin Rover took over Leyland and used their Beans Industries plant. The West Yorkshire Foundry were taken over by Eisenwerk Bruhl in 1986, who also purchased Beans Industries in 1995 with the casting business at Beans to later become Ferrotech. Some heads were green or black unlike all the other A plus small bore yellow heads. No extra lugs on 3 middle front head studs even on this early head for pre production Metro’s with date marking 21G8 for 21st July 1978. I have also seen April 1979 and July 1980 heads with bypass hose for Mini. Metro A plus heads and engines started being fitted during 1978-1980 on pre production cars. Some J5181 castings had good port shape and valve seat positions which were favoured by engine tuners for 1000cc Autocross regulations.

CAM4810 between 2&3 rocker posts with strengthening lugs on the 3 middle front studs with a B for Beans Engineering in a circle between 4th rocker post and end of head above the 8th valve, cast with part numbers either way up in same location as they are only inset plates and they used a plug in the rocker oil way feed rather than rivet. With the Beans emblem at the 8th valve they were all drilled for heater valve and by pass hose but for the Metro used a plug in the by pass hole and blanking plate for heater valve. A few Metro type less heater valve and by pass holes but I have one with D8N actually lead free, which might have been modified post factory build.

CAM4810 between 2&3 rocker posts correct way up but with letters BIL (Beans Industries Ltd) cast correct way up by end of 4th rocker post above 8th valve instead of the original Beans logos. Picture on left-Mini with heater valve and by pass holes drilled. Picture on the right where it is not drilled for Metro use and no by pass hose started mid 1980’s to early 1989 and had a rivet rather than a plug fitted for the rocker oil feed gallery but not necessarily lead free. Only 1 out of 7 in my collection was Mini and only one Metro with lead free inserts which had 9H9 N by thermostat (Aug 1989). Mini head above left with BIL were from a Mini City E 1985 and Mayfair 1986. These heads with BIL probably were the outcome of another set of tooling before Leyland being broken up in 1988 and their management team buying out Beans at the time. The last 998 Minis were built in 1992

Beans industries emblem on the left followed by 2 of the other stampings found on their heads and ND on the end of the cylinder head by thermostat cover indicating a true factory machined lead free type head.

N/D upside down just about readable behind thermostat and the screw holding the plate on for casting looks like a sunburst which denotes this N D head as definitely being lead free from Rover October 1989 until end of production in 1992 on Mini and Metro 1990.
CAM4810 upside down between 1&2 rocker posts with 3 strengthening lugs on 3 middle front studs and a B in a circle between 3&4 rocker posts from Beans engineering usually had N/D with the visible plate screw looking like a sunburst behind the thermostat housing, denoting unleaded seats fitted. Some Minis after 1986 were unleaded to special order according to parts lists and different valves used on hardened seats, but all were definitely using lead free top grade seat inserts from Oct 1989. Rivet in the oil way for rocker feed rather than a plug for all these later heads. Out of my 16 heads only 2 were mini at time of this article and were made until 1992. Earliest head I have seen is 8J8 (8th Sept 88) and latest 4B2 (4th FEB 1992)
Mini had a by-pass hose facility but Metro and Allegro were not always drilled for the by pass tube. The remote heater valve was fitted to Mini from 1989 and the last heads were not drilled out for heater valves, just a large detent for where the water gallery could be machined if required.
Note 6. CAM4004-1.0625” inlet and round port


Has the extra air holes by spark plugs for anti pollution exhaust ports for countries like Australia and fitted around 1975/6-79. Air ports at front blanked off. The casting number usually starts with an “E” for export reading ECAM4004 and is sideways by the 8th valve between 4th rocker post and end of head. Painted black or in red oxide they usually had single groove valves so technically just before A plus yellow heads. Probably a Beans head
Note 7. 12A185. 1.156”inlet valve and square inlet ports

Be aware that these small bore 9 stud heads from Wellingborough with a W to denote their foundry used the same 12A185 number as the Cooper S large bore head 12A185/AEA626 from Morris engines but this the small bore early 1961 first generation head, fitted to 997 Cooper 1961/2 up to approx the first 14,000 cars with double valve springs, usually on a 12A204 engine block. It had square inlet ports with recessed back manifold face ,MOWOG above 12A185 in centre and the Wellingborough emblem”W in a triangle within a circle between 3&4 rocker posts, but it also made its way on a few other early 1100cc such as MG1100. Also used on 948cc 9CG engine number for Sprite Mk2 1961 and Midget Mk1 May 1961 to Oct 1962, hence maybe the two combustion chamber sizes found (dished pistons with 8.3cr for 24.5cc for 9C engine), (flat top pistons with 9.1cr for 26.1cc for 9CG engine) using 12A185 head, Leyland ST booklet C-AKD1021 backs this up as Sprites/MG were built at Abingdon with heads from Wellingborough and the engines built at Morris Engines. The USA market experienced the alternative heads being fitted as cars were rushed there for sales, racing and promotion with different combustion chamber sizes. It was probably originally cast at the same time as the 12A185 large bore and valve heads, at the foundry in Morris Engines when Eddie Maher, Harry Weslake and Daniel Richmond were trying to develop BMC competition engines suitable for Formula Junior, plus the Healey Company racing Sprites early 1960’s and then Formula 3 from 1964 for John Cooper inline engine single seater race cars in tandem with what BMC might require which ended up as part of the 1071cc and then 970cc S large bore engines development program. Also see Note23 for other anomalies of 12A185 from Eddie Mahers XSP department at Morris Engines where small bore heads were converted into an 11 stud head with large bore credentials and strange looking thermostat hole, plus one with a split twin centre exhaust port. The rare AEA405 small bore head similar to 12A185 valve sizes is also listed under Note23 experimental XSP heads, as it was another anomaly.

Same 12A185 head as above but from a car with 24.5cc for dished pistons.
See Note12 for the large bore engine type with 12A185 cast in centre plus AEA626 between 1st and 2nd rocker posts and Morris emblem between 3&4 rocker posts known as the yellow head which is a pre runner to the AEG163 with bronze guides and EN214N 1.401 inlet and 1.22”exhaust valves which were shorter than the 12G940 casting valves, whereas the 12G 940 in all its guises used cast iron guides as standard.
Note 8. 12G202. 1.156”inlet valve with square inlet ports


MOWOG above 12G202 between 2&3 rocker posts and W in circle from Wellingborough between 3&4 rocker posts. With recessed manifold back face, this is from Morris Minor 1000 with 1098cc engine

Small bore head started with a recessed back manifold face for all 1098cc engines from August 1962 on the Morris 1100 being built at Cowley when they had to get away from the duplicated casting number 12A185, which this 12G202 basically was and also fitted to the 2nd generation of 997 Cooper from around August 1962 until December 1963, just under 11,000 from a total of under 25,000 Coopers built. Morris Minor 1098cc 1962-71. Some MG midget /Sprite 1098cc with 10CG engine 1962-64 last few or as aftermarket. Austin/Morris 1100 from 1963-74. A40 Farina 1098cc from 1963-67. A35 Vans to 1962 and A35 Estates to 1968 with 1098cc. Later type with flat machined manifold face, last Austin 1100, Marina 7CWT van, Allegro 1973-1980. Mini special editions 1979/80. Mini Clubman manual 1975 to 1980. Spain replaced 1098cc with 998cc in 1974. Heads less a by pass hose tube are probably Allegro 1973 on. All 12G202 heads have a temp transmitter hole.
Over 4,000 a week were cast at times and the total made was well over 1 million from the records that I could accumulate from cars and parts sales. A very common and available small bore head. Produced in such huge volumes for so many variants mostly as detailed, but all are interchangeable. Nothing rare or different in performance.
Below is the earlier recessed or sculptured type manifold face which was phased out from the 70’s. NOTE- the very visible inner square inlet ports.

All 12G202 heads had a square inlet ports with the shape starting about ½” in and early types had recessed back face for manifolds. Some later heads had flat back faces for manifold as shown below.

The flat non recessed manifold face started with the 12G940 in 1966 and gradually phased in on the small bore heads on tooling updates for 12g202 with square inlet ports, the first one I ever saw from Morris Engines Foundry in 1968 but universally most other small bore heads started by early 1971-2 and for Allegro 1973 and then Mini Clubman 1975 on.



12G202 number cast between 1&2 rocker posts above 2&3 valves, MOWOG in centre between 2&3 rocker posts and either MC or M above 23453 between 3&4 rocker posts, from Midland Cylinders, recessed back manifold face. Early circlip type cotters and valves, 1961 until 1971 often on Morris Minors and Austin and Morris 1100. Also seen fitted to 997 Cooper post 12A185 heads.

Same as head photo above but with only M between 5&6 push rod holes from Midland Cylinders

12G202SM from Sterling Metals less MOWOG emblem so probably machined at Longbridge and destined for Austins.
12G202SM between 3&4 rocker posts with nothing else, less Mowog motif between 2&3 rocker posts (can look like 2G202SM on heads cast with MOWOG, all with early valves and circlips on cotters. Recessed manifold back on both types, all pre 1968 and later type flat manifold to 1970—

Cast by Sterling Metals, still using the MOWOG emblem originally used for Morris versions.
12G202SM cast between 3&4 rocker posts above 6 and 7 valves, MOWOG in centre between 2&3 rocker posts or position higher under 4 and 5 push rod holes with recessed back manifold face. Early valves and circlips on cotters, but clips missing on this 1967 head.

MOWOG above 12G202 cast between 2&3 rocker posts, Morris Engines logo between 3&4 posts with recessed or flat back manifold face, but still with early valves and circlip cotters. Mainly off Morris Minor. This 1968 head has a flat machined manifold face. I have a 1963 head with sculptured manifold face and MOWOG in centre slightly lower down. Wellingborough used their W logo in a circle to denote difference.

MOWOG in centre above 12G202 cast upside down between 2&3 rocker posts and M logo between 3&4 posts, with flat back manifold face and majority with early valves with clips. 1968 on

12G202 central markings upside down if looking from front of head with spark plugs facing you, no other relevant markings from Longbridge except Beans dating. Note- see lugs at back of 3 central front studs.
12G202 cast upside down between 2&3 rocker posts with no other markings with extra 3 machined head stud lugs and flat back manifold face, some with W,Z or M by No1 valve. Probably cast by Beans, No MOWOG or Beans symbol. 29F8 by thermostat denotes 29th June 1978 production, most are 1978-80. Most I have seen were fitted to Mini Clubman’s.

12G202 cast upside down between 2&3 rocker posts with but with the (B) for the Beans logo above the 8th valve and usually X or Z by No 1 valve with extra machined lugs behind 3 central front head studs and with flat back manifold face and late valves. 1978-80 so could be fitted to Allegro, Clubman Estate & Mini Special. A batch were also produced for export and British Leyland stock as bare heads with guides only.

Complete head same as below left, but on right with a different position of casting number

12G202 cast sideways by number 8 valve beside 4th rocker post and no other markings with flat back manifold face with extra 3 machined head stud lugs, late head and some castings look like 12G20 as the last number 2 is lost in push rod hole.Head on left was 21st November (21L8) and head on right was 30th November (31L8) but both 1978 heads, so a tooling change. Used 1976-79 for Allegro and Clubman estate. I assumed these were cast by Beans pre Ferrotech days as they had taken over all Wellingborough work.

12G202 at back of thermostat housing with M for Morris Engines foundry motif also.
12G202 on ridge behind thermostat housing with small M in a triangle symbol beside it and flat manifold face, extra 3 head lugs, rest of top face has very few markings. Circlip type collets on valves on head shown. Last type of 12G202 casting made at Morris Engines foundry and also sold as last replacement UK stock for spares as part number 28G193 circa 1973/4. The date for this head was 11th Dec 1971 made at Coventry. Fitted to last of Morris 1100 plus Austin and Vanden Plus until 1974 plus early Allegros where changeover to later type valves and cotters occurred. I also found these fitted to 1098 Clubman 1975 -1979 but with later type valves and no circlips.
Note 9. 12G201. 1.156″ inlet valve with square inlet ports

12G201 this early head has the full NMQ BMC logo.
NMQ was the company name of Nueva Montana Quijano, with heads cast by at Los Corrales De Beulna near Santander, Spain who fitted these to Authi versions of the Morris 1100 Jan 1967, MG1100 from Sep 1967 and with recessed manifold face plus the later head shown below to the Austin1100 from April 1972. Nearly all of the car and parts were produced in Spain to pacify their trade protection policies and import tariffs, as a joint venture with BMC. The Santander bank were also capitalists in NMQ.

BL in place of the NMQ logo pattern shape above 12G201, cast between 2&3 rocker posts. Fitted to all AUTHI 1100 ADO16 range after July 1967 when BL took on a 51% shareholding of NMQ, but with BL running out of money in 1976 they closed Authi. Same as UK 12G202 valve sizes but different volume combustion chamber. These had recessed manifold faces and good core centralising when cast, making them ideal for modifying. A few seemed to end up on other Italian 1100 variants and Mini Spares imported many of these later heads as shown with BL motif above for re-sale. 12G201 was the drawing number at BMC for the 12G202 design.
Note 10. 12G206 1.156″ inlet valve with square inlet ports



Similar looking combustion chamber shapes to a 12G295 but smaller inlet valves.
Often described with the wrong description and wrong inlet valve sizes as an alternative to 12G295. Even our catalogue had inlet valve size wrong with a typing error from the late 90’s on hard copy which many have copied without research but I can definitely confirm the following. The Inlet valves were original 1098cc size at 1.156″. Cast with MOWOG above 12G206 between 2&3 rocker posts, it has a recessed back and Wellingborough symbol in a circle between 3&4 rocker posts. Has square inlet ports and no locating ring recess and same inlet valve size as 12G202 but often increased by .060” to the 1.218 inlet for either valve seat repairs or performance. The better flowing combustion chamber shape is 28.4cc but smaller and deeper at around 0.450” whereas the 12G295 is larger and shallower at around 0.430”deep, usually 20-25 thou difference. Although listed as part number 28G191 by BMC in AKD3509 parts list for very early 998 Cooper with low 8.3 CR, and a few 9-1CR- (I can only ever remember seeing the raised D shape pistons for 9-1 CR with 12G295 castings back in the 60’s). Mainly fitted to inline 1098cc 10CG to engine No 14877 on Sprite/Midget 1962-4, pre 12G295 fitment, plus a few early MG1100 and somehow even the odd A40 and Morris Minor with 1098 engines but probably had the compression ratio modified.
Keith Calver says- The 206 is a much better head for road use and modifying – including those with a sporty camshaft. Far less prone to cracking as well. The 12G295 invariably has bigger intake ports and very shallow short side radius. For most road applications the ports are too big as standard – It does not need port work doing, just sorting out the valve seat shape and valve throat area. The inlet valve throats often have very, very thin seats so the valves seem to be barely hanging on. Also generally the throat has what appears to be an insert fitted because the underside is square stepped in shape like a shallow insert, they are cast like this. The 295 was produced for Group 1 race/rally homologation in mind at a time where big was beautiful. Keith Calver is still amazed at some of the valve sizes they crammed into them.
Note 11. 12G295 1.218″ inlet valve 1963on

A)Early head with recessed back, Mowog is much lower than push rod holes.
A) Even though all Coopers were assembled at Longbridge the first heads had Mowog above 12G295 cast in the middle between the 2&3 rocker posts, below push rod holes. Note- Wellingborough logo in a circle between 3&4 rocker post on this early head which has a recessed back manifold face.

B)This is the 12G295 with flat or recessed manifold back but see Notes A and B
B)Mowog above 12G295 in middle but cast higher with M just touching push rod holes, Wellingborough symbol in a circle between 3&4 rocker posts and 13 under 12G295 often had a flat back manifold face, but not all. 14 and higher numbers were usually flat back


A later casting had the 12G295 casting number lower in the centre and mostly with 55 upside down but without Mowog and only the Wellingborough symbol between 3&4 rocker posts plus the flat back manifold face. All have large inlet ports with recess holes for locating ring 12G297 to mount the inlet manifold. First found on MG1100 from Oct 1962, plus Riley Kestrel 1100, Wolseley 1100 and Vanden Plas 1100. Fitted to 1964-66 MG & Sprite with 10CC engine number and all 998 Cooper 1963-69 apart from early cars 9FA SA H 101 -1035 and L101-1581 according to the parts list AKD3509, which used 12G206 of which many went to the USA on MG’s.Read KC view above on 12G206 Note10 for the 12G295 differences.
Some early 295 heads from records originally seen but now lost implied they were also cast in North works Longbridge and the drawings below I have had for years are now so badly faded it can hardly be read. The 12G294 drawing was also the part number used by NMQ Spain for sales if they made these heads which would usually have had their logo on. Head below has an A above 3 rather than a W for Wellingborough emblem between 3&4 rocker posts, which might have been cast at Longbridge if not Spain. I have never seen anything other than these two manufacturers marks indicating where they were made. Nearly all I have see have the W for Wellingborough Foundry in a circle.

“A”instead of Wellingborough logo between 3&4 rocker posts sold as 12G294 in Spain.

12G295 BMC Longbridge drawings 1961/2, using 12G294 as their drawing office number.
Note 12. 12A185/AEA626. 35.6mm(1.401″) inlet 31mm (1.22″)exhaust


This 11 stud large bore head has MOWOG above 12A185 between 2&3 rocker posts and AEA626 between 1&2 rocker posts and note the Morris engines foundry emblem between 3&4 rocker posts below MCC. Known as the yellow head owing to its primer coat colour, with recessed manifold face, bronze valve guides and EN214N valves it was fitted to the first 1071 Cooper S in January 1963 until November 1963. Alternatives of this head were also fitted to the 948cc inline A series and other racing engines back in the early 1960’s with the block modified to take valve pockets. Some heads did not have the heater valve facility and were usually for Formula Junior or XSP Sprite engines and even a casting marked AEG220 with the last number lost in a push rod hole. These large bore heads had the oil gallery plug for rockers plug at the bottom of the head. The 14E 3 upside down under 12A185 is the old Austin/Morris Ferrous casting date number standards used during 1950’s onwards for US federal regs on safety. The date on head above is 14th May 1963 (see article at end for dates) Pre runner to AEG163 this head is often misidentified as there was a 9 stud small bore head with same part number 12A185 for the 997 Cooper but less the AEA626 markings (see Note 6). For other 12A185 anomalies and XSP experimental heads with strange shape thermostat holes, plus 8 ports. See Note 23

A is most large bore heads from 1965 on, B &C are the unique oil feed gallery of 12A185/AEA626
Pic A) of AEG163. If you look at first rocker post to below No1 push rod hole there is a raised casting oil feed bridge from the rocker cover gasket seating area to carry the oil to the No 1 rocker, as per all other later large bore heads. First AEG163 also had no oil feed bridge See NOTE 13
Pic B) of 12A185/AEA626. shows the lack of an oil feed bridge which is unique to this head as the oil gallery ran along the base of the head face as per all original designed small bore heads.
Pic C) of 12A185/AEA626. A repair where the head has been skimmed to much you can see the braze covering a copper tube oil feed gallery from the top left oil feed hole along the face to where it rises to feed the rocker post. I have seen a few like this on full race heads where a high CR was required. There is another anomaly of this head without heater valve drillings and a different casting number AEG220 probably used in head development and for Sebring Sprites and Formula Junior engines built for John Cooper which I have put under the XSP and experimental heads under Note 23

AEA626 performance head on left that never broke oil gallery, plus Fig C as shown above that did

Same head as first pictures above but the date stamp is 10E6 which is 3 years later May 1966 when only the 1275 Cooper S was in production with the AEG163 head, so therefore this is an unknown production or stamping anomaly or the 6 is probably a dodgy 3.

Note 13. AEG163 35.6mm(1.401″)inlet with 31mm(1.22″) exhaust 1.22”

First type AEG163 with no oil bridge for rockers feed, indicated by red circle
A) First type-Very early 1071cc S head and I have only seen 3 so far where there is no oil feed gallery for rockers on top which is similar to previous 12A185/AEA626 yellow head, few of these being fitted to Formula Junior cars. EN21 4N nimonic valves, steel caps and bronze guides this large bore 11 stud head was fitted to MK1 Cooper S and were known to be prone to valve seats cracking with the large valves, plus stud hole breakage on some weak rocker pedestal platforms. All originally known as blue or brown heads and introduced to Cooper S 1071 from Oct 1963 and 970/1275cc when released until phased out by 12G1805 early 1968. The 12A185/AEA626 was known as the yellow head. So I am sure the head above was known as the brown head. These did have heater valve drillings but no dates, with M between 4&5 push rod holes for Morris engines foundry Coventry in centre. Mowog between 2&3 push rod holes and AEG163 between 6&7 pushrod holes. The AEG220 head under Note 23 is very similar but less heater valve drillings.

B–2nd type with upper rocker oil feed before the Morris Motors logo moved to behind thermostat.
B– MOWOG between 2&3 push rod holes, AEG163 between 6&7 push rod holes with M for Morris Motors emblem in centre between 4&5 push rod holes and all upside down from the front view on early heads, with M being replaced by a date stamp and the M going on a ridge behind the flat surface of the thermostat housing area as per picture below. EN21 4N nimonic valves, steel caps and bronze guides this large bore 11 stud head was fitted to MK1 Cooper S and were known to be prone to valve seats cracking with the large valves, plus stud hole breakage on some weak rocker pedestal platforms. Note the flat brass plugs in photos above and below which were above the inlet/outlet alignment cores for checking and removing wire swarf holding the pattern equipment together. This head came off a 1071cc car. All originally known as blue or brown head and introduced to Cooper S 1071 from Oct 1963 and 970/1275cc when released until phased out by 12G1805 early 1968. The 12A185/AEA626 was known as the yellow head. I thought this head with upper oil gallery was the Blue version and I was shown and told of the differences in 1963/4 but as the heads were so common I never recorded the information.

C-3rd type,Similar to FIG B head above but no M markings in centre, this head has the M for the Morris motors engine foundry on tab by the back of the thermostat face. MOWOG between 2&3 push rod holes, AEG163 between 6&7 push rod holes. Steve Harris has half of a cut up head with AF492 stamped behind thermostat housing which was an airflow and development head worked on by George Toth at Downton in Feb/March 1963 for Bill Appleby and Eddie Maher at BMC Morris Engines. Daniel Richmond and staff played with this head and had previously tried his prototype AEG163 on 997cc Cooper engine (bored to 1088cc) and undercut the block to accept the larger exhaust valve and then managed to influence Leyland to reduce the exhaust valve size from 31mm to 29.4mm for his future design of the castings for his reliable 12G940 head that would follow. This head also had the later upper rocker post oil feed gallery similar to 2nd type and all future large bore heads.


D-Same as photo above, MOWOG above AEG163 between 6&7 push rod holes, with M in half triangle for Morris Motors Coventry Engine Foundry on a ridge behind the flat surface of thermostat housing area. Part date stamp on some between 4&5 push rod . Note the dished brass plugs mainly on this type. Most AEG163 heads had a full recessed back face for manifolds but the last 1275 heads had flat back down to below port holes and then recessed bottom as shown below.

5th type,Last AEG163, 1275cc type of manifold face with same top face AEG163 markings as Fig D pics.

Face of AEG163, original large EN21 4N inlet & exhaust valves clearly showing on the AEG163 head.
Note14. AEG305 35.6mm(1.401″)inlet with 31m(1.22″) exhaust


Manifold face is typical of a recessed or sculptured type early face. Notice this does have the bridge for the oil feed from the seating area of rocker cover gasket to the 1st rocker post.
Rare, large bore head with AEG305 between 6&7 push rod holes and MOWOG between 2&3 push rod holes both cast upside down. Bronze guides and EN214N valves with 11 studs and recessed back. I have seen quite a few examples and my good friend Steve Harris still has an original that Downton air flow wizard George Toth worked on and rumour suggests probably only 50-100 were ever made. Identical to AEG163 except used on Sebring Sprite 1071 (XSP2036) bored to 1098 and Cooper single seater racers using the newly introduced large bore 970cc “S”block bored 40 thou oversize to 997cc for 1964 Formula 3 rules, where the heater tap hole was not drilled as per photo above, but a water elbow was usually added on side of the head for plumbing to help cool the 4th chamber and port. I have also seen this head on an early Cooper 1275cc engine less heater tap drillings. Really an XSP head but seen on a few other vehicles so I have listed it here. Emblem on ledge beside thermostat, rather than at the back of the thermostat is M for Morris Motors at Courthouse Green Coventry where these XSP heads progressed under Eddie Mahers team guidance. I have seen two old originals in blue protective paint but do not believe they were called the blue head which I was led to believe was the second AEG163 with upper oil feed for rockers.
Note 15. 12G940 1.3125″inlet 1.156″exhaust –Pre A plus

Very rare early 940 head with AEG163 shape and head face characteristics but small valve.
Mowog over 12G940 in the centre but has all the casting features of AEG163 with the Wellingborough emblem in its usual position between 6 and 7 push rod holes. Instead of the flat top face it has shrouded ends similar to the AEG163 but one extra alignment/cleaning plug above the extra bolt hole. I was not sure what section to put this very rare head in but as it has a similar shape and design to AEG163 I have listed it after that item but maybe should be with 12G1805 Note18.

X above 12G940 in centre and Wellingborough emblem between 3&4 rocker posts. Predominantly the type with more metal around the exhaust guide boss and did not flow as well in std form as later types.

Most early heads from 1966-70have 12G940 in centre with either an X above, or MOWOG above or below the 12G940 number, mostly with a W in a rhombus diamond shape for the Wellingborough Foundry trade mark, between 3rd & 4th rocker posts. The later ones around 1970 on, had 12G940 only between 2&3 centre rocker posts with less material around the guide itself which provided a better flowing exhaust port in standard form. All had the flat machined back manifold face and a “flat top face” type as above and did not have the extra strength lugs behind the front 3 head studs unlike the Beans head from 1972 on, that did have strengthening lugs. Early 12G940 Mowog castings were first used on MG Midget and Sprite from 1966 followed by Austin/Morris 1300 range 1967 where they were sought after by all engine tuners as they offered greater potential for modification to increase performance and reliability compared to the AEG163 head. These early 12G940 known as flat face heads had well aligned cores from their new pattern equipment castings and smaller 33/29mm valves with more metal which was an engine tuners delight to put their own shape valve throats and size valves in. The type without the ‘X’ are predominantly better in the exhaust port valve guide boss area with less material around the guide itself which gives a better flowing exhaust port in standard form. Pre A Plus heads from Uk cars were fitted to-Mini 1275GT 1969-80, Austin 1300 1967-74, Morris 1300 1967-73, MG1300, Vanden Plas 1300, Wolseley 1300, Riley Kestrel 1967-68, Austin Allegro 1973-80, Morris Marina 1971-80, oddly some Marina Ital van until 1984 and Sprite/Midget 1966-74 with heater valve drilled and by pass hose.

Early full flat face, from Wellingborough Foundry with W emblem between 6&7 push rod holes and MOWOG above 12G940 between 2&3 rocker posts. No reinforcement lugs and machined at Morris Engines.


Two other photos of flat face types. Left hand picture Wellingborough emblem above Leyland Roundel emblem between 3&4 rocker posts from the 1970’s. Right hand picture is a 1972 Beans head same type as full head pictured above but this had heater tap hole drilled.

Flat face 12G940 with CBS emblem between 3&4 rocker posts of which I have seen a few, mainly 9 stud. No reinforcement lugs behind front head studs typical of CBS product, dated November 1974.

Another of the Pre A Plus later flat face types from Longbridge suppliers CBS with recess by thermostat hole. The 12G940 cast between 4&5 push rod holes with no strengthening lugs on inside of front 3 studs. CBS logo between 3&4 rocker posts partially hidden by pattern equipment pin.

The 12G940 above shows that you can only see 2G94 with SM underneath from Sterling Metals, also with indentations where 11 stud version could be drilled as it was also machined as 12G1805 also. These are all mid 1960s to very early 1970 heads. No reinforcement lugs on front. I have only seen a few with the double indentations recesses as shown above from Sterling Metals and CBS, plus a few early types from Wellingborough Foundry which had MOWOG above 12G940, strangely many of these were destined for MG and Sprite with 12G938 stamped on them. Some had other numbers punched on them about 1/8” tall on the area behind the thermostat housing which was to denote what vehicles they would fit on when assembled. See (Fig A) below 12G938 for UK and reputedly 12G293 for 12G1316 smog emission version of 12G940 although I have never seen one, both denoting double valve springs for Sprite/Midget from 1966-74 which had good centralised cores for modifying. (Fig B) below, the 12G1805 see Note 18, from Wellingborough Foundry indicated the fitment of larger diameter inlet valves and 2 extra stud holes from 1968-74.


Above is the only casting oddity I have seen where 12G940 is sensibly part numbered behind the thermostat and always visible dating from about 1977-80, pre A plus with the extra lugs behind the 3 central head stud holes which many seemed destined for CKD kit cars sent to Belgium or Portugal, Innocenti and Holland, mainly for the Allegro which were built there, looks like a Beans head but no other identifying markings. Most seem fitted to Allegro 1977 to 1980 pre A plus exports, as described above.
Apart from the 12G1316 smog port head, see Note17 the only other 12G940 derivative anomaly is the good head from Authi Spain, it had 2G93 above the NMQ-BMC in the centre, see Note16.

Flush strengthening lugs behind 3 central front bolt holes as preferred by Beans foundry.
Flat face 12G940 with Beans emblem below it to the left. 4E3 denotes cast 4th May 1973 but the heater hole is blanked off so probably from Allegro or an inline A Plus series such as Maestro. Machined flat lugs behind 3 central stud holes started about 1972 with Beans. This head had no by pass hose either meaning a non Mini original fitment.Longbridge machined

Green arrows for 3 large reinforcement lugs and Yellow arrows for 4 smaller semi raised lugs from Wellingborough Foundry
Wellingborough heads had their own method of reinforcements using semi raised lugs behind the front 3 head studs as above, not flush like Beans heads but with 4 smaller lower ones for their wall support by all valves. Started around Mid 70 heads until end of flat face type
12G940 A PLUS versions 1.3125″(33mm) inlet 1.156″(29.2mm) exhaust 1980 on
Below, a repainted sample of an A plus where the 12G940 casting number is still proud to about 1989, plus an identical head in original colour below showing the extra ridges on top, oil way bridge for rocker feed, thermostat and heater raised areas valve to rocker cover gasket face, hence the earlier heads 940 head being known as flat face versions. 12G940 is between 4th and 5th push rod holes from late 88 to 89 on.

Early A plus heads pre 1989 still have the 12G940 visible and mostly without lead free inserts, but with date stamps just above thermostat housing area. See very end of articles for lower picture original red colour match.

A plus heads from Longbridge 1980 on, mainly cast by Beans and latterly renamed as Ferrotech have less material in them giving them thinner wall sections where the water jackets were enlarged and improved, all 12G940 heads are interchangeable but check drilling differences for your own requirements. Metros, Maestro, Cooper RSP, Ital or Allegro, did not have a by- pass hose facility but RSP unleaded had heater tap drilled. Morris Ital 1980-82 and Marina 1.3 did have by a pass hose. All A plus had the extra machined flat lugs around the back of the 3 front centre stud holes, plus raised ribs from the rocker cover gasket surface out to the thermostat and also an area behind it, plus raised ridge to the heater tap location and one from 4th rocker post. The first A plus as per the picture above still had the 12G940 very visible and raised but the next generation 1989 on as per the Turbo head pictured below in original A plus head colour are machined down to the surface of the rocker cover gasket face which takes away nearly all the original 12G940 casting number but left more metal in the head face which apparently helped cooling still leaving the head with the original depth of 2.750″which in turn makes them useful if a larger combustion chamber size is required. Introduction of a noticeable rivet in the back of the thermostat end to close off the drilling hole for oil way to rockers. Single collet valve stems were being phased out by late 1983 and replaced by triple groove valves with a new top cap and twin groove collets CAM6975 with a 14 degree angle as opposed to 10 degrees maybe instigated by Lotus for use on the Metro Turbo 1982-90 enabling valves to turn/spin more freely. Late 1989 the 12G940 appeared between 4 and 5 push rod holes sometimes reading 12G94 as the 0 was in the push rod hole. Previously the 12G940 mark had been below the push rod holes as shown below.

This mid 1989 on A Plus Turbo head shown above had a T punched on the area by the non drilled heater tap location similar to all Turbo heads, which used 8mm wide sodium filled valves for better cooling, as noticeable on valves 4,5,8 with different top caps. Note, the extra strengthening lugs machined flat where Pre A plus just had lumps and the extra metal on top to cater for the larger internal water jackets and the top face machined down to original 2.75″ depth making the 12G940 nearly illegible and leading up to the start of Lead free heads 1989. Fitted to MG Metro Turbo 1982-90 and ERA Turbo 1989-90 but early heads pre engine no 102640 has single collet valves until 1984. So many core changes and casting shapes have been produced that with the later A plus varieties included there must be at least ten different types of 12G940. Most A plus heads were cast originally at Beans Industries Tipton which then became Bruhl UK which later became Ferrotech and machined at Longbridge. Lead free from late 1989
Note16. 12G939 (2G93)1.3125″ or 1.401″inlets, 1.156 exhaust– 9 or 11 stud

9 stud head with 1.3125″ inlet

12G939 AUTHI Spanish 11 stud 1969 version of 12G940 head for 1275cc models with large 1.401″inlet valves but marked 2G93 as first and last numbers lost in push rod holes.
Made by Nueva Montana Quijano from Pamplona, in Spain for Authi 1275cc models 1968-76 and was good for modifications. I have seen 9 stud versions with 33mm inlet on mini 1275C/1275GT and 11 stud with 35.6mm size inlet valves on Mini Cooper 1300 models and none indicating that the 2G93 could be 12G939, the Rover drawing being 12G938 always one number lower. Drawing also mentions 12G950 as No2 which would equate to 12G951 cylinder head which I have never heard of or seen.

Note17. 12G1316 1.3125″inlet 1.156″exhaust

Wellingborough foundry logo in a circle on early head with X above 12G1316

Wellingborough foundry logo not in a circle on early head with X above 12G1316

Later Wellingborough foundry logo in a circle on a head without an X above 12G1316

With threaded port holes for air pollution pipes

Without air pollution holes drilled on lugs
All based on a 12G940 1969-73, the USA anti- smog casting has either MOWOG above 12G1316 or just 12G1316. “X” above the number are earlier type predominantly with larger exhaust valve guide boss that did not flow quite as well as later heads. The air holes are on the pillars beside the spark plug hole and can be blocked off, originally for non-air pollution countries. I have seen at least 4 types of these, even where the lugs are not drilled on a new replacement head sold as part number 38G431 and as per red head shown above. Most have the Wellingborough W symbol and very good cores for modifying. 12G293 stamped by thermostat signified twin valve springs for Sprite and Midget, with W in rhombus diamond between 3 and 4 rocker posts all seem to be cast by the Wellingborough Foundry
Note 18. 12G1805 1.401″inlet 1.156″exhaust with 11 stud holes

12G1805 with the “S” stamped above the thermostat area but too small at this angle to see but check below. Flat front type typical of all early Wellingborough 12G940 heads. W in a triangle for Wellingborough Foundry logo between 6 and 7th push rod holes.

Most 12G1805 UK heads had the following symbols below them, A,K,R,S,U but I have seen odd heads with an H,P and W which I have yet to quantify from other original vehicles. I did try to work out what the letters were for with many owners who have different original cars and heads but nothing true tied up.
12G940 in centre sometimes with X above it and Wellingborough W symbol with 12G1805 and another larger letter usually A,K, R, S, or U stamped by the thermostat back face, I have seen one with H, P and W but cannot verify their authenticity. These all had 11 stud holes which originally denoted larger 1.401” inlet valves. The 12G1805 casting cores were not always consistent and any 12G 940 castings can be converted to have either the extra stud holes or the larger inlet valves fitted aftermarket. Most 12G1805 Cooper S heads will have the Wellingborough logo. If you have an 11 stud “S” head without any 12G1805 markings as described they might be from S Africa 1275GTS Clubman from Blackheath plant, as I imported over a hundred at least. Any 11 stud “A” plus head is an imposter of the 12G1805 and probably converted from Note 19 the next listed head. The 12G1805 was designated to be fitted fitted from 1st Jan 1968 to MG1300 and Riley 1300MK2 1967-69(not Kestrel), Austin or Morris 1300GT to 1974, Cooper S Mk2 from early 1968 and all Cooper S Mk3 1970-71. Fitted Riley and MG from Sept 1967 with 12G engines.


White arrow pointing at faint TC for Twin Carbs for Mini GTS from S Africa head
The head above is the last 12G1805 I purchased from BL in S Africa which was also used for core pattern equipment for our alloy heads. The black marking still visible was done by our foundry, but the head only has 12G940 in the usual place and no foundry identification or date other than 29C for 29th March plus TC inverted for Twin carbs as shown above. I purchased over 100 of these heads along with many other parts from Leykor (Leyland S Africa) when it closed down mid 1980’s and believe these were from the Gearings Foundry or the Blackheath plant as there were a few foundries under Blackheath’s control but they did get their original samples from the UK Wellingborough Foundry in 1967 to start their business trials making heads and blocks. The car was called a Mini GTS but had the Clubman body shape, built at Blackheath plant in Cape Town from July 1973 to March1980 .

This 12G1805 version less the X above Mowog had better flow around the exhaust guide boss areas which was my reason for purchase with my staff discount, but heads and all parts did go up quite dramatically in the 1970’s. My basic wage in DEC 1968 was £14.50-per week but paid monthly with a bonus to a total of £66-£70 making my wage up to £16 to £18 for a 46 hour week and I was getting married 3 months later with a mortgage looming. BMC wages in 1965 were £24-15 for a 41 hour week. Obviously we were not in a workers union, unlike BMC.
Note 19. A Plus 12G940- Non S 1.401″inlet 1.156″exhaust with 9 head stud holes.


Original large inlet valve head A Plus 9 stud fixing and photo above with new valves
Same as other 12G940 A plus castings, with only 9 head stud fixing holes but fitted with the large 1.401 inlet valve. Many of these have now found their way on to other cars and drilled with the 2 extra stud holes claiming to be for Cooper S. No by-pass hose or heater tap hole originally on these as heads came from Vanden Plas Metro manual 1984-89, Maestro 83-86, Montego 84-89, MG Metro 82-89 and GTA 89-90, Morris Ital 82-84 but earlier 80-82 Ital heads were small valve. Some were rumoured to be on a few Mini Cooper RSP.
Note 20. 12G940B 1.3125″inlet 1.156″exhaust

From 1991 the SPI head had a new number 12B940B also cast on the end of head as shown with the B sometimes looking like an 8. Note heater tap hole not drilled. ALL LEAD FREE
12G940B cast between 4&5 push rod holes (but often the B is lost in the push rod hole) and also 12G940B was cast in the heater tap end of the new casting introduced in 1991 for the SPI/Mayfair single point injection cars with no drilling for heater tap, no temperature transmitter hole or by pass hose, all are lead free and it has a noticeable large rivet in the back of the thermostat end to close off the drilling hole for oil way to rockers. The pre runner to the MPI which like this is supposed to have the best cooling jackets to date but with less metal on the walls, especially on the two end exhaust ports on the ‘outer’ walls when modifying. Has 3 small core plugs rather than brass plugs in head gasket face. This SPI head was also used on other variants and modified by the factory with by pass hose and temp transmitter hole for HIF38 carb fuelled cars where required. 12G940B is the first 1275cc lead free head recognisable by its part number from the factory. Also found on Mini with HIF38 carb, Mini SPI, one claimed to be on RSP Cooper but unlikely as standard. Cast by Ferrotech and are all date stamped correctly.
Note 21. LDF105380 1.3125″inlet 1.156″exhaust

The last A series casting made by Ferrotech for the MPI looks different on the front face as it has 3 bolt locating holes for an alternator where the temp transmitter used to be and they are meant to have the best cooling characteristics for the Mini. There is no 12G940 marking on this head but just the part number on the end. These can be used on any 1275 Mini but the heater tap holes, temp transmitter hole and by pass hose will have to be drilled and the thermostat seating area machined deeper to accept the thermostat or by using a special gasket PEQ100650SPACER. The temperature transmitter hole which is missing can be drilled out and threaded in the location of the bottom alternator bracket hole. Mini Spares has sold many of these heads as performance items with the areas mentioned above converted.
Note 22. C-AHT347 ALLOY HEAD 1.406″inlet 1.161″exhaust

Mini Spares own version of 5 port alloy head with photo copyright by Matt Woods
Based on the last 12G1805 samples of Leyland 12G940 flat faced modified casting but made in alloy to aid heat dispersion, weighing only 5.7kg with fully modified ports, bronze guides with safety clips, plus EN214N race quality valves. 21.3cc to 21.5cc combustion chambers, the same as all original large bore heads. Beryllium valve seats spaced to avoid cracking. Heads are heat treated and pressure tested before and after machining giving a top performance product C-AHT347 for all bore sizes. Also available with larger 37mm inlet and 31mm exhaust valves spaced further apart for strength but using colsibro guides and titanium top caps for one the best performance heads available at exceptional value, either C-AHT347RACE for plus 40/60 thou up to 73.5mm oversize pistons and C-AHT348RACE for std/20 thou bore size.
Note 23. 8 Port heads C-AEG612 IRON and C-AHT346 ALLOY and XSP

C-AEG612 top view cast iron head with M for Morris Motors foundry on tab behind t/stat

C-AEG612 Front view and with 4 exhaust ports at back.
Known as the cast iron 8 port it was cast at Morris Motors Foundry circa 1965/6 homologated with 35.6mm(1.400″) inlet valve and 29.3mm(1.15″). These heads were jointly designed Eddie Maher and Harry Weslake with the Morris Engines (Maher) version having square exhaust ports and the Weslake head having round exhaust ports as confirmed by Jack Cramp the Weslake flow tester but many people call it Weslake because of his involvement and the W stamped on them which is actually an M for Morris Motors . Any body doubting this should read article about Sebring car registration number 7080AC by Jack Wheeler. Replaced by the Arden Alloy head first cast in 1967 as this cast iron head had too many problems with cracking even after being tuftrided and lowering of compression ratio. I owned engines with both types of 8 port heads fitted, cast iron with fuel injection although Morris Engines and Eddie Maher the designer favoured the 4 amal carb set up and the alloy version with fuel injection. I sold the iron head engine with injection as the heads were subject to cracking but I still have the engine with the alloy head with Tecalemit injection laying around somewhere in our storage units sadly deteriorating and bits lost after 40 years of neglect even though I had been offered huge amounts of money for it over the years. This head with square exhaust ports has Mowog and casting number 707 1280 which was homologated for Mini and 1275GT some earlier series numbers were 707 280, 707 1172 and 707 1180


C-AHT346RACE Alloy head-see our website for pictures and full information
Originally cast at BMC/Leyland’s Birmid/Qualcast factory for Jim Whitehouse in 1967 but only made for race in mind with a 16.4cc combustion chambers which Mini Spares modified in 2012 to 21cc for road use and big bore engines, with slightly longer valves than the original already longer valves to compensate for the tooling partial renovation to give larger combustion chambers and then fitted with modern day valve seats and guides. Original valves sizes on the Whitehouse tooling when purchased by Mini Spares were 35.6mm(1.401″) and 30.93mm(1.218″) as Jim had been looking for more power which we certainly did obtain after our 2012 changes. Homologated in July 1970 with only 29.3mm (1.15″) exhaust valves. From 2012 the valves sizes on C-AHT346 were changed to 35.6mm and 30.5mm exhaust which flow bench testing proved to be optimum sizes. For extra performance C-AHT346RACE has 37mm inlets and 30.5mm exhaust. Valve centres were moved further apart to give reliability. The alloy head was homologated for the Mini but not the Clubman, maybe by error. See Mini Spares article New Arden 8 port heads.


Parts of the original tooling for Arden 8 port head as purchased from Jim Whitehouse.

XSP extra special products
XSP engine numbers (XSP1973-7 for example) were allocated to special engines from Morris Motors engine branch, mainly for the A series but included others and made famous by the Healey Sprite Sebring endurance and Le mans races. The Healey Sprite deigned by BMC and Donald Healey to which the car took its name was thrust into the sporting world by Donald Healey Motor company with cars supplied by Abingdon in 1959 and duly prepared to race in Sebring endurance races in USA where they came 1st, 2nd, 3rd. Many of the cars and subsequent years from the sixties stayed in the USA but other very rare samples of these heads are still around in the UK with some even adapted to fit on minis. Most of the experimental and oddity heads were produced around 1960-64 used for Sprites, or Cooper mid engined racers for Formula Junior to 1963 along with other heads already itemised previously.
12A185 XSP small bore with 11 stud modification

12A185 marking only, 11 stud head using thermostat hole, no temp transmitter or heater valve holes.
Mowog above 12A185 in centre and M for Morris Engines symbol between 3&4 rocker posts. This head had 3 brass plugs as used on large bore head, although probably only fitted to small bore as the valves sizes are not that large. These heads all seemed to use domed head valves with small collet grooves to accept later 88G459 cotters and none had the heater valve outlet hole drilled. Exact valves sizes of current production vehicles had to be used but these could have up to 31.75mm inlets and 26.99mm exhaust valves. It had the 11 stud head conversion by adding extra metal in the thermostat seating area but less heater valve and temperature transmitter hole. Used on inline engined Sprites for Healey and other privateers.

12A185 marking only, with normal 3 exhaust ports only, plus 11 stud head fitment and see below for the combustion chamber shape and valves fitted

12A185 number only, combustion chambers not opened up as much as 8K985 at end and smaller valves but note, it’s adapted for large bore water ways with 3 brass plugs fitted.

With its unique cut out thermostat housing with forged rockers as taken off an original Sprite XSP engine
12A185 with AEA626 XSP for small bore block for Cooper T56/59

12A185 with AEA626, XSP by Eddie Maher for small bore block with std valves with 11 stud fitment in modified thermostat area, no heater valve or temp transmitter holes.
Mowog above 12A185 in the centre with AEA626 between 1&2 rocker posts and the Wellingborough logo between 3&4 rocker posts. This head could well have been used on some of the 948cc over bored XSP engined Sprites . The AEA626 number is part tooling from the early S large bore version but used for the T56 and T59 Cooper mid engined racers on the 1961/2 1095cc 67.6mm over bored small bore 948 block with valve pockets in the block, probably using Powermax 18512KR oversize flat top pistons and special con rods. It still had the 11 stud head conversion by adding extra metal in the thermostat seating area but less heater valve and temperature transmitter hole. This tooling was amortised to make the 4 exhaust port head for the Sebring Sprites which are mentioned next. Valve sizes up to 33m inlet and 26.99mm for both heads.
12A185 with 8K985 Twin stack exhaust port head

12A185 head with 8K985 small bore 11 stud head

MOWOG above 12A185 in centre but has 8K985 between 3&4 rocker posts which we believe all had the twin stack centre exhaust port shown below and large valves cast late 1961 at Morris Engines, Courthouse Green.

Twin centre twin stacked exhaust port unique to this head designed by Eddie Maher.

Combustion chamber shapes for the Sebring twin stack exhaust port head.Believe this had 33m inlet and 26.99 exhaust
Looking at the combustion chambers on this head it might have been used on the 948cc Sprite Mk2 bored plus 60? to 995cc but on this head note the waterways are as found on small bore heads, the 3 large holes parallel to spark plug holes are usually plugged on large bore. Definitely used for 1962/3 Sebring races but Geoffrey Healey’s books and records from 1978 are unclear of exactly what engines it fitted but they also built a new 1098 coupe with a special light alloy body for the 12 hour endurance race. However, according to the XSP records these heads were fitted to the 4 alloy bodied Donald Healey Sprite Mk2s 995cc from 1962 built at Cape works Warwick for the Sebring 12 hour and 3 hour GT Race and had reg numbers WD9251 driven by Steve McQueen the actor, WD9252(Innes Ireland) WD9253 (Pedro Rodrigues) and WD9254 (Stirling Moss), WD9251 the car driven by Steve McQueen stayed in America and the other 3 were returned to England. WD9252 and 3 were sold with WD9253 sold to John Harris in 1964 did not have this head fitted at this time and was subject to CAR SOS for its latest owner aired in April 2015. WD9254 was broken up after severe accident at Silverstone driven by Christabel Carlisle in about 1963.XSP1973-6 was fitted to 9251WD.

Eddie Maher in his drawing office in 1954, copyright of British Motor Museum Gaydon
AEG220 prototype large bore from Eddie Maher department for Don Healey race Sprite


Similar to 12A185/AEA636 large bore head with no upper oilway bridge at rocker post but has no heater tap drillings as used on XSP Sprite or Cooper FJ engines. Morris Engines logo in centre.
I have only ever seen two of these rare heads which have no heater valve drillings suggesting it was for XSP Don Healey’s Race Sprites or mid engined Cooper use but was probably replaced by the later AEG163 first edition, or AEG305. The only marking visible EG22 is probably AEG22 something (AEG220?) and the only part number I know close to it was AEG226 the first performance head gasket Payen introduced for Leyland after gasket failures and became the basis for C-AHT188. The top photo right hand end, looked like it has a date mark for 1962? See my Eddie Maher article for this XSP head fitted to works Sprite 9253WD owned by Jonathon Whitehouse-Bird.
AEA405 small bore head casting

Another of these small bore heads circa 1961/2 which I have only ever seen a few via Speedwell and Ian Walker Racing as it was mainly early Healey, Sebring Sprite, A40 Farina and Cooper 997cc days. From memory one had 997cc size inlets 1.156″and std 1″ exhaust but the others either John Sprinzel, Graham Hill or Ian Walker used on Sebring or LeMans Sprites and Johns A35 had larger valves which I never took notes of. One head in USA at a mid 80s Mini meet had no valves but looked larger seats than std. Another turned up recently on a forum with 29.3mm exhaust and 32.5mm inlets plus being fully modified, similar valve spec to standard 1275cc head, maybe done in its later days. The heads were cast at Morris Engines, Courthouse Green, probably around the very early 60s when Eddie Maher was doing all his head work and special XSP castings with different size valves and modifications for the Healey Sprite and competition work on small bore engines. The AEA prefix for the part number mainly originated from early inline engine A series heads such as A35, Healey Sprite and A40 Farina with 948cc engines. Le mans car used 64.5mm bore 76.2mm stroke (996cc) whereas the Cooper T52 racer had 994c with 64.4mm bore. The only other note I ever had listed for this head stated it was for a 1000cc to 1100cc formula junior engine for 1960-63 regulations in Germany.
19D4078 AF series Weslake small bore large valve

Doc Shepherds 1960 Weslake 19D4078 head for his 998cc A40 Farina

19D4078 Weslake designed head was originally designed and used for Dr George Shepherd on his A40 Farina which won the 1960 British saloon car championship. I believe Weslake himself and Don Moore Racing modified the chambers and fitted large valves but when fitted, it outwardly looked the same as 2A629 as in Note 1&2. Downton managed to fit 32mm inlet and 28mm exhaust to 2A629 heads. Thanks to Ricardo Nobre and Will Grant for pictures for some of the XSP heads and others, of which I have not used but kept for my records.
ALLOY HEADS IN GENERAL 9D2853 AF series alloy head

This is the only known type of Factory looking 5 port alloy head known and never in production as far as I know. Made for small bore it has no temperature transmitter hole but has heater valve and by pass facilities. Known as the AF series head you can see the AF between the black arrow pointing to the part number. Known as a Weslake alloy head one was used on the A30 prototypes according to reliable sources at the time but only iron heads were used for production.
SPEEDWELL alloy head


Speedwell alloy heads were made in Italy early 1960’s for 850/997 small bore and were very unreliable, often porous with dodgy valve guides and little lifespan. Speedwell were just down the high road from where I worked and were regular customers and friends but even their workforce could never praise the product. See the “Mk1-Performance Forum” on their website which has further details and pictures.

Howley overhead cam head

Designed by John Chappell this overhead cam head was a hybrid of what the BMC factory had been working on and I bought the only fully converted head as used on his 1275GT and the tooling. The head was loaned to a London customer John Salter for his Min Rod racer in late 1988 to race in 1989. He disappeared as a customer and his car was apparently sold a lot later with the head fitted only to appear in a forum requesting any details known about it. The tooling was sent to Graham Russell an engineer and friend of Keith Calver down in Australia and I am still awaiting its return although it will never be made again by Mini Spares as better 5 ports and 8 ports heads are available now.

Howley tooling basking in the sun ready to be packed/shipped home from Australia

2024 Tooling back in the UK at last but probably never to be remade just like Rover version
7 PORT Cylinder Head

Various companies have been involved in manufacturing the alloy the 7 port head, Specialist Components, Pierce in USA and Webcon in UK. With the inlet manifold shape it only allows fitment of DCOE carburettor or specialist made injection systems.
Blanking and drilling options for water ways on original heads. If you do not require heater take off valve use blanking plate 2A180 and gasket 88G221. Options for by-pass hose is blanking cap CAM4126 or remove by-pass hose adaptor and fit blanking plug 88G619. For single point injection only – blank water temp gauge sender unit hole off with 5/8″UNF threaded plug (part number 5/8UNF). To change post-1992 head (including MPI variants) to pre-1992 fitment –
Drill 9/16″(14.5mm) hole through counter-bored heater take-off hole (1/4UNF heater tap retaining stud holes are already in place) or remove blanking plate if fitted. For by-pass hose, either drill/tap 5/8″ UNS (16TPi) hole in required place as per original and fit by-pass hose adaptor 12A2075, or alternatively drill/tap 5/8″UNF and fit adaptor tube 12H1405MS, or blank water pump port off with blanking cap CAM 4126 and either drill 1 to 6 of 1/8″/3mm holes around thermostat periphery or fit blanking sleeve 11G176 (really not good for road use – recommend thermostat is fitted). For water temp gauge sender unit either drill/tap port out to 5/8″UNF thread or remove 5/8″UNF socket headed grub screw if fitted.
Downton and Maher cylinder head involvements
It was rumoured and might well be a fact that Daniel Richmond owner of Downton Engineering along with Eddie Maher worked on the design of the 12A185 and AEG305 for the Cooper S and 12G295 for BMC but almost certainly the 12G940 casting that replaced the AEG163 casting was Downton’s Daniel Richmond’s work for which he received royalty payments, but that all finished with the shake up of BMC to Leyland in late 1969. Just to add to the confusion was the Wellingborough Foundry logo (a large W in a rhombus diamond) placed in a circle found on many small bore heads and just a W in a triangle for 940 heads plus others, which many wrongly assumed was for the Weslake design and patents. The logo for Morris engines was also confusing as it looked like a W on some castings but the M for Morris had a bit of the apex missing on the triangle top. Morris at Coventry did own Wellingborough Foundry originally and used the same triangle basis for their logos. The logo similarity was confirmed 17/9/2024 by Peter Cross from Production Control at Wellingborough 1960-70.

Eddie Maher in 60′ to 70’s-read my article “Making of the Cooper Engines”with Eddie Maher
Also Eddie Maher must be mentioned as he was an engine performance genius who originally worked for Riley cars before Morris Motors Ltd took the company over. He was involved in A series engine development for the XSP engines on Austin Healey, the early Cooper S plus John Cooper single seater inline race engines, plus many head configurations in the sixties including the 8 port head and much more, but very little can be found out about his work and design thoughts or personal/working life within BMC until I contacted his son and done research to write an article about his work.
803-998cc to 1098cc engine head swaps. Leyland found the stronger 998 A plus engine with its new block/piston, high compression set up was apparently only 1 bhp down against the 1098cc engine power and more economical which then started a gradual phasing out of the 1100 longer stroke engine on some vehicles. The figures have been disputed but the question still arises on forums whether you can fit 998 heads with 1.0625″inlet on 1098 engines and vice a versa with the larger 1.156″ inlet head to a 1000cc. Either head can be fitted as the difference in compression ratios equals out the valve sizes. The 12G202 1098cc head made with the larger inlet valve has extra flow area around the inlet valve whereas just putting a larger valve in the small valve head creates shrouding and no power increase. The 12G202 larger inlet valve head can help to give higher revs mid range and a few BHP more on the 998 but when gas flowed and CR increased it can give very good results. Putting the small valve head on 1100cc block can lose a few BHP at most and revs are diminished. In Layman’s terms at worst, it feels about the same to the equivalent of power loss or gain with having new or worn pistons/rings so is slightly noticeable. Both these heads can however be greatly improved by removing metal around the large valve guide seats especially the exhaust and de-shrouding the valves, especially the inlet and either type worked by a specialist can give great results. So basically, you could put either a 998cc small inlet valve head or 12G202 larger inlet valve on either small bore block in std form without much noticeable difference difference apart from needing a carb needle and timing change. You can always put a larger valve small bore head on a small bore engine but carburation, timing, or a rolling road set up will be required. The compression ratio will also need to be checked and usually the head shaved but “A Plus” 998 heads do not need as much material removed as the earlier 998 which had a lower compression. 24.2cc seems to be used on most Mini Spares modified heads for 998cc but 24.5-25.5cc combustion chamber is ok for use with flat pistons. Usually about 25 -30 thou needs skimming from std 12G202 when fitting to 998 block dependant on pistons fitted and compression ratio required.

2A629 was the original Harry Weslake combustion chamber/port design that was more or less identical on 12A1455,CAM4004 and CAM4180. Next we have 12G201,12G202 and 12A185 which used the next size up 1.156″ inlet valves and BMC had to de shroud the combustion chamber in that area to make it flow but they look the same, but with an increase in combustion chamber capacity. 12G295 had a different shape chamber as per Daniel Richmond’s design which he also closely followed on his Stage One Downton modified cylinder head kits for Special Tuning Abingdon to suit the Mini and 1100. The Stage One 850 kits sold at £44-00 in 1967 pre VAT days. The 12G206 had fairly similar design chamber shape as the 12G295 but with 1.156″ inlet whereas the 12G295 had the largest inlet valves 1.218″ of all the small bore heads. 12G940 used the same design by Daniel Richmond but a larger shape combustion chamber with less cubic capacity and different larger size valves.
When modifying cylinder heads Keith Calver and other head modifiers have passed on the following knowledge-Generally, what makes a head casting better than another one for modifying is being able to identify the more centralised cores, and certain other beneficial offsets. Smaller-valve heads on the 12G940 (those with 33,3mm inlet valves) especially pre A plus are better for modifying as there is more material in the valve throat to achieve better shapes because they increased the A Plus head coolant jacket volume to improve cooling (more coolant volume). The result is thinner ‘wall’ sections meaning easier to go through in all the wrong areas. Coupled with some very wayward core shift during casting makes A plus heads less desirable to modify. A+ castings from 1991 are also from different tooling to the earlier A+ castings 1980-1991 but then most of all, it depends on how much material you remove to achieve the performance you are looking for or deem necessary, to achieve your preferred port shapes. Head gurus have spent a great deal of time flow testing and then dyno testing their types of modification and much less material is taken out these days so they have fewer problems going through the walls. Race heads can still be a worrying ordeal depending on the casting. Although every modifier knows a 12G940 casting I am sure all the different types shown will include their favourites.
BMC/Leyland heads part numbers and the casting reference numbers used are listed below but there were a few other odd part numbers issued by the factory not listed but these were the main ones.
BMC PART NUMBERS/ CASTING NUMBERS
2A629/ 2A613
12A1456/ 12A1455 or (28G283 early 99H) 12A1459 Auto
12A185/ 28G141 Small bore
12G202/ 28G193
12G206/ 28G191
12G295/ 28G222
AEG163/ 38G360
12G940/ 38G399
12G940 35mm inlet/ CAM6633
12G940 Turbo/ CAM6979
12G1316/ 38G431 also a 12G939 on 940 casting
12G940B/ unleaded TAM2153
Foundries and brief history of owners. Many of the foundries were sold off and then sold on again as the car industry diluted its requirements with mergers, rationalisation and cost cutting exercises to finally suffer through recessions and shrinking market.
Cylinder Head Manufacturers. Originally Morris Motors owned and used Wellingborough Foundries as a supplement for Morris Engines. Sterling Metals had supplied Wolseley blocks and heads before A series days so were owned by Morris Motors anyway. Longbridge, mainly used GKN, Birmid Group and Beans for Austin cars. The Birmid Qualcast Group of companies we mainly remember as the lawnmower manufacturer, but they had traded under many company names in the past such as Birmac, Birmid, Birmal, Birmingham Aluminum castings, Birmingham Motor Cylinders and Dartmouth Foundries who manufactured heads and many other parts. Birmid in Smethwick amalgamated with Qualcast to become Birmid Qualcast. When Austin and Morris amalgamated in 1952 they eventually started joining forces in production and suppliers with a great reluctance as many still felt as if they were competitors. Wellingborough Foundry also supplied Longbridge especially after BL was formed in January 1968.
In the end only Birmid Qualcast who owned all the other foundries and Beans were left as the suppliers to Rover.Birmid had also stopped supplying by 1982. Beans as part of BL at Tipton who took over Wellingborough in 1969 were latterly known as Ferrotech and became the only supplier left after 1982.

Longbridge North works foundry produced A series head castings until the move to East Works known as the Coften Hacket new engine plant in about 1968-9. Not exactly sure when the old North Works foundry closed or stopped production but hoping any ex employees can offer info on what heads were cast there and when they brought in outside suppliers heads only. At the end of the 70’s a large investment programme for the Mini Metro resulted in the massive expenditure on updating all power units to A plus for October 1980 release. A series heads were only produced for the early cars such as A30/35 at north Works but mostly supplied by other suppliers within the BMC group. B series blocks/heads were their main production. This factory and area were known as “The Austin”
Sterling Metals (SM) along with Birmingham Aluminium Castings, Midland Motor Cylinders (MC) had amalgamated in 1929 as part of the Birmid Group and from their foundry in Northey Road, Coventry and then from their Attleborough Foundry, Nuneaton from 1956 on, suppled many of the early small bore castings to Morris Motors and Longbridge. They were at the first London motor show I attended in 1963 and had become part of Birmid Qualcast by 1982 and had stopped casting heads. Qualcast were part of the Blue Circle Group by 1988. Blue Circle as in cement suppliers and now owned by Tarmac & CRH PLC.
Midland Motor Cylinders known as MC or MMC for the ferrous metal division were big suppliers to Longbridge for Austin production but their name and buildings were all part of a big group at Smethwick in Birmingham more commonly known as Birmid and Qualcast etc. Heads with MC or RMC in the casting were mainly small bore type said to be from MC but if it had MOWOG also on the head they were probably for Morris Motors engines.


Beans Industries Ltd emblems found on heads
Beans, taken over by Triumph in 1956 and part of Leyland by 1960 the old Triumph factory at Tipton became part of part of BL producing castings and blocks for commercial vehicles plus coaches and took control of Wellingborough foundry in 1969 before rebranding as Beans Engineering in 1975. In 1988 the Leyland Group was privatised by the conservative government and Beans Industries was acquired by its management team. After this Beans acquired Reliant in 1992. Mini 998cc cylinder head production also ceased for assembly line 1991/2. In 1995 Reliant failed which forced Beans into receivership and the Tipton, Staffordshire, West Midlands factory was purchased by the German company Eisenwerk Bruhl in 1997 trading as Bruhl UK, who had invested heavily making it one of the most modern up to date and efficient plants in Europe, supplying Rover cylinder heads and blocks but the debts incurred finally forced them to sell the business which then had another management buy out and became known as Ferrotech, who carried on as the only head supplier for Mini at Rover until 1999 and cast its last part September 2005 after the collapse of Rover.

C&B Smith logo is on the top deck face of the heads
CBS – C &B Smith of Stewart Street Wolverhampton. In 1965 became part of GKN FORGINGS and CASTINGS, then in 1982 became Birmid Qualcast specialising in cylinder heads and general engineering. Birmid was sold to Blue Circle industries 1988.

Not the clearest of emblems when cast on cylinder head top face with part numbers
WYF. West Yorkshire Foundries. In 1964 they were supplying Jaguar and `Coventry Climax blocks with special blocks/heads for racing. In 1966 they built a state of the art gravity die casting factory and supplied Rolls Royce, Aston Martin and Jaguar plus the favoured Mini heads. As a BL subsidiary, in 1980 along with other BL closures such as MG Abingdon they laid off half of its workforce and by 1982 were only a small supplier until BL was finally sold to Eisenwork Bruhl in 1986. In 1992 it was acquired by VAW Motorcraft and Norse Hydro joined up with them in 2002 to be renamed as Hydro Aluminium Motorcast Ltd and many other names including the word “Alloy” before settling the company name as VAW Motorcast Ltd. Longbridge were also supplied by Birmid Qualcast Group of companies who we remember as the lawnmower manufacturer, but they had traded under many company names in the past such as Birmac, Birmid, Birmal, Birmingham Aluminum castings, Birmingham Motor Cylinders and Dartmouth Foundries who all manufactured heads and many other parts.
Michael Edwardes joined BL in 1977 under a labour government and started closing down nearly a third of all plants, halving the workforce to try and stop the money losses and by 1982 when his contract ended he resigned. In the end it had annoyed Thatcher the new conservative prime minister from 1979 as she wanted to sell off more parts of the company whereas Edwardes always requested more funding for Rover with its new Metro in sight. Rover would limp on until 2004/5 which kept some foundries producing heads and blocks, a lifeline except for Classic Mini.
Morris Motors Engine Department and their Wellingborough Foundry

Morris Motors engines logos from different heads and all used correct full date markings

M in triangle on left for Morris Motors and 2 on right with W for Wellingborough Foundry.
From about 1961 Wellingborough used the W in a circle on their small bore heads and then on some 12G1316 heads but only the W in a triangle less the circle on 12G940 heads.The Wellingborough Foundry along with Morris Engines were the only companies that produced every design of UK “A series” head between them that I had seen up to 1981 when they closed and Wellingborough foundry were last used for producing the A Plus 998cc heads for early pre launch Metro plus Mini. Morris at Coventry had purchased the Thomas Butlin Foundry at Wellingborough in 1947 which had room for expansion and started producing blocks and heads in 1951 and as a major casting supplier they would supplement Morris Engines who they answered to as they were ultimately their boss. In the 1960’s to early 70’s they supplied heads for both Morris Engines and Longbridge for the ADO16 1300 power unit, Coopers and MG. Morris engines started at Courthouse Green, Coventry in 1929 and a huge production factory for engine and its components was built in 1938 as part of their expansion program. All the early Cooper S and experimental development heads with the M logo for Morris Engines factory were produced mostly under Eddie Maher’s team directions from 1960-65 for special race development for Sebring and Lemans sprites plus John Cooper single seat inline engined racers. Many 12G940 castings plus the 12G1805 large inlet valve heads were from Wellingborough and many machined at Morris Engines at Courthouse Green as well as Longbridge. Wellingborough foundry also produced many of the early MOWOG castings, who by 1965 had cast over a million A series heads and blocks themselves. In 1968 British Leyland were formed which absorbed all the original plants of Jag, Rover Triumph,(JRT) Leyland and British Motor Holdings. The Tipton plant (originally Triumph) also known as Beans Engineering now owned by BL from January 1968 took over the Wellingborough Foundry in February 1969 taking much of Wellingborough foundry work and all of it finally by Wellingborough’s closure in 1981. The Morris Engines foundry division was closed in 1979 which was 50 years after it had opened and the remaining part of the company were told in Oct 1981 that they were doomed, finally closing in July 1982. Morris Engines dated many of their castings fully when required to comply with the British Ferrous Casting standards except XSP and Cooper S heads but Wellingborough only used day and month because they had to ascertain and reduce the cause of defective scrapage by having daily meetings with Inspection and Senior managers and therefore felt that only the day and month were required as issues were never more than a few weeks after production. This however would not seem to fall in line with USA requirements as per British Leyland (Austin Morris)Standards?
Date Standard for Ferrous Castings
First issued in 1953 for the introduction of US federal regulations on Motor Vehicle safety, castings became date stamped up until the 1990’s. The only problem was that the last number, say “3” for the year 1953 was the same for 1963, 1973, 1983 and 93. The first 1 or 2 numbers were for the date and the single letter that followed was for the month. The letter “I” was not used for the month to save complications with the number “1”. The last single number being the year of that decade. They would have known whether it was 1950,1960,1970 or 80s, by the vehicle part made or built but mainly drawings in that decade. There were also some markings showing what shift or batch the items were made from, but they could appear before or after the main date information which can be confusing or hard to work out on heads unless somebody can provide further proof or information. Examples after BL explanation sheets.


Example= 21J8 is 21st September but the year could be 1968 or 1978 Pre A Plus, or 1988 for A Plus. 21DJ8 the D would indicate the batch or shift it was cast on so still dated as previous. The D shift number could also appear after the year such as 21J8D so you need to decipher the main date numbers and letters discarding the shift. Any head with the Wellingborough motif which are the hardest to date, had to have been made before its closure May/June 1981 at the very latest before the final tooling was moved to Beans at Titpton until or after September 1981 but I would imagine any tooling with the W for Wellingborough would have been erased. I have no record of what was made up to the dates shown as the transfer of work to Beans had started in 1980. Wellingborough heads only had the day and month but not the year designated, usually between 1 and 2 rocker posts and sometimes the year beside the 4th rocker post platform but only their design drawings with batch numbers and date markings would have shown this. Some Wellingborough heads were rumoured to have the year number under the thermostat housing where the by pass hose sits. Many small bore heads and all “A Plus” large bore heads have the date stamp by the thermostat housing, except of course, for most Wellingborough castings.
Hopefully any ex employees of Wellingborough, Longbridge or any other foundries will provide any extra information to help us build up facts of the long lost or destroyed records. Although these are only my personal recollections on cylinder heads it’s better than anything else available and although I have researched my findings for errors I am always updating and checking facts for the next generation of mini enthusiasts. If you have an original car and about to take the head off please let Mini Spares know the year, manifold face type, top face picture with valves plus good photos we can use, or any photo better than those I have used so far, are all welcomed. I started this printed format of editorial long before pre covid times and not necessarily in any specific order, from old notes and memory over a period of 60 years. This is all still work in progress for future Mini owners-By Keith Dodd
Cylinder Head colours
John Parnell and Steve Burkinshaw released in Cooperworld magazine a colour match of the darker red A plus heads pre MPI. The code being —Munsell = New = INDURA PLUS. NTC cellulose.AZIF2. 1 litre Full Gloss 90% –available from Bodicroft Supplies-Chalk Hill Watford WD19 4BL The BMC green paint was supposedly Brunswick Green but there seemed to be a few shades used over the years from different foundries and machine finishing shops. The other colour mentioned is Mid Bronze Green but all seem period correct whereas the one Mini Spares stock is EP3A BMC Mini Engine Green by Classic Colours is available as GAP109 for brush application or GAP410 by spray which customers seen happy with.
Blocks and Heads leaving Wellingborough were sprayed eau de nil, possibly some red. This was a primer coat to seal and prevent rust. From 1967 Longbridge heads were painted with a finished coat and waxed after assembly in red or black it is believed, as pre 1967 heads although painted with a rust inhibitor, final coat after assembly the rust still came through.

