MSE6 - POST 1992 Unleaded Stag
Modified to give maximum performance gain for cost. Combustion chambers, inlet and exhaust ports extensively re-worked. Stone-ground finish in ports promotes ultimate fuel atomisation. Three-angle valve seats in head. Super-quality MG Metro valves modified to increase airflow.
MSE6 - POST 1992 unleaded stage 2 (Road Rocket) large-bore head
Part No Applications: MSE6, TAM1059, TAM1061, TAM2069, 12G1963, 12G1015, ADU4905
Inlet Valves: 35.6mm(1.401") dia. Original equipment type P/No. TAM1059
Exhaust Valves: 29.2mm(1.150") dia. Original equipment type P/No. TAM1061
Exhaust seats: Latest type Beryllium-based for lead-free fuel P/No. TAM2069
Valve Guides: AE Hepolite cast iron P/No. 12G1963
Valve Springs: Nominal 140lb. Max actual valve lift 0.400" P/No. 12G1015
Stem Seals : Latest 'top-hat' design with tensioner springs (inlets) P/No. ADU4905
Chamber Volume: Nominal 20cc
Combustion chamber volume used to give slight static compression ratio increase over
MSE6 - POST 1992 Unleaded Stag
Modified to give maximum performance gain for cost. Combustion chambers, inlet and exhaust ports extensively re-worked. Stone-ground finish in ports promotes ultimate fuel atomisation. Three-angle valve seats in head. Super-quality MG Metro valves modified to increase airflow.
MSE6 - POST 1992 unleaded stage 2 (Road Rocket) large-bore head
Part No Applications: MSE6, TAM1059, TAM1061, TAM2069, 12G1963, 12G1015, ADU4905
Inlet Valves: 35.6mm(1.401") dia. Original equipment type P/No. TAM1059
Exhaust Valves: 29.2mm(1.150") dia. Original equipment type P/No. TAM1061
Exhaust seats: Latest type Beryllium-based for lead-free fuel P/No. TAM2069
Valve Guides: AE Hepolite cast iron P/No. 12G1963
Valve Springs: Nominal 140lb. Max actual valve lift 0.400" P/No. 12G1015
Stem Seals : Latest 'top-hat' design with tensioner springs (inlets) P/No. ADU4905
Chamber Volume: Nominal 20cc
Combustion chamber volume used to give slight static compression ratio increase over
MSE4 - Post 1992
Modified to give maximum performance gain for cost. Combustion chambers, inlet and exhaust ports extensively re-worked. Stone-ground finish in ports promotes ultimate fuel atomisation.
MSE4 - POST 1992 unleaded stage 2 (Road Rocket) large-bore head
Part No Applications: MSE4, C-AEG544, C-AEG106, TAM2069, C-AJJ4037, C-AEA526, ADU4905
Inlet Valves: 35.6mm(1.401") dia. Tuftrided EN214N s/steel P/No. C-AEG544
Exhaust Valves: 29.5mm(1.161") dia. Tuftrided EN214N s/steel P/No. C-AEG106
Exhaust seats: Latest type Beryllium-based for lead-free fuel P/No. TAM2069
Valve Guides: Magnesium bronze P/No. C-AEA526
Valve Springs: Nominal 180lb. Max actually valve lift 0.500" P/No. C-AJJ4037
Stem Seals: Latest 'top-hat' design with tensioner springs (inlets) P/No. ADU4905
Chamber Volume: Nominal 20cc
Three-angle valve seats in head. Cooper S size valves with current maximum flow profiles and Tuftrided for durability/longevity when used with unleaded fuel (hence 'black' finish).
MSE4 - Post 1992
Modified to give maximum performance gain for cost. Combustion chambers, inlet and exhaust ports extensively re-worked. Stone-ground finish in ports promotes ultimate fuel atomisation.
MSE4 - POST 1992 unleaded stage 2 (Road Rocket) large-bore head
Part No Applications: MSE4, C-AEG544, C-AEG106, TAM2069, C-AJJ4037, C-AEA526, ADU4905
Inlet Valves: 35.6mm(1.401") dia. Tuftrided EN214N s/steel P/No. C-AEG544
Exhaust Valves: 29.5mm(1.161") dia. Tuftrided EN214N s/steel P/No. C-AEG106
Exhaust seats: Latest type Beryllium-based for lead-free fuel P/No. TAM2069
Valve Guides: Magnesium bronze P/No. C-AEA526
Valve Springs: Nominal 180lb. Max actually valve lift 0.500" P/No. C-AJJ4037
Stem Seals: Latest 'top-hat' design with tensioner springs (inlets) P/No. ADU4905
Chamber Volume: Nominal 20cc
Three-angle valve seats in head. Cooper S size valves with current maximum flow profiles and Tuftrided for durability/longevity when used with unleaded fuel (hence 'black' finish).
MSE3 -Pre 1992
Modified to give maximum performance gain for cost. Combustion chambers, inlet and exhaust ports extensively re-worked. Stone-ground finish in ports promotes ultimate fuel atomisation.
MSE3 - PRE 1992 unleaded Stage 2 (Road Rocket) large-bore head
Part No Applications: MSE3, C-AEG544, C-AEG106, TAM2069, C-AJJ4037, C-AEA526, ADU4905
Inlet Valves 35.6mm(1.401") dia. Tuftrided EN214N s/steel P/No. C-AEG544
Exhaust Valves 29.5mm(1.161") dia. Tuftrided EN214N s/steel P/No. C-AEG106
Exhaust seats Latest type Beryllium-based for lead-free fuel P/No. TAM2069
Valve Guides Magnesium bronze P/No. C-AJJ4037
Valve Springs Nominal 180lb. Max actually valve lift 0.500" P/No. C-AEA526
Stem Seals Latest 'top-hat' design with tensioner springs (inlets) P/No. ADU4905
Chamber Volume Nominal 20cc
Engine - Identification Data Updated
If you have the engine tag still attached to the engine - just in front/below the thermostat housing - or perhaps the original engine number in the log book then the following should help you determine which engine you have.
For Metro units, see 'Engine - Metro identification data'.
Original engine identification numbers
850cc
8A Austin up to 25000
8MB Morris up to 25000
8AM Austin & Morris 25000 onwards
8AH Austin & Morris Automatic
8AJ Austin & Morris closed circuit breathing
8AK Austin & Morris automatic with closed circuit breathing
8WR Wolseley Hornet & Riley Elf
8AC Moke
85H/101 All variants 1969 onwards
Note: third suffix letter denotes compression type, L = Low, H = High, e.g. 8AM/U/H101 denotes high compression.
998cc
9WR Wolseley Hornet & Riley Elf Mk2, pre closed circuit breathing
9AD Austin, Wolseley Hornet & Riley Elf Mk2 with remote type gearbox and closed
Cooling - Controlling water temperature
The introduction of the Cooper S proved to be a testing time for the Mini’s systems, but conveniently provide a guideline as to what the standard cooling system was capable of - that used on the ‘S’ was marginal to say the least!
It wasn’t uncommon for many S’s to spew water from their overflow pipes when ever it was doing anything other than a steady 70 miles an hour, over-heating eventually caused through water loss. Perhaps some deductions can be made from the following…
There are a number of elements involved in controlling water temperature. Some confusion over what to sort first when over-heating occurs leads to wasted time and money, and possibly terminal engine damage. Maximum power is usually generated from A-series engines at 70 – 75 degrees C (160 to 170 degrees F). The main problem with this on a road car is the oil’s unlikely to get hot enough for maximum performance – the results outlined previously.
Cylinder head - Identification by casting number
A+ head castings - despite having the same 12G940 casting number - are considerably different in appearance, loosing the flat area behind the thermostat housing and around the rest of the rocker/head stud areas to a sculptured look - where these areas are replaced by a 'sunken' cast finish.
The A+ castings were introduced with the appearance of the Metro in 1980, although some late 1275GTs (1979-on) had them fitted. Generally they are easily recognised by their colour - a putrid yellow on the small-bore castings and bright red on the large-bore ones, a paint finish that is VERY difficult to remove, even in a chemical tank.
The MG See bottom for useful part numbers.
Now this may not be super-sonic speed-inducing power, it could just as well be for maximum economy. In either case, it's the engines volumetric efficiency (VE) under scrutiny - it's ability to breath in as much correctly proportioned air/fuel mix as possible in any given situation.
Cylinder head - Min Tec head range
I'm often asked about the range of cylinder heads I do for Mini Spares/Mini Mania, so here's the low-down…
Although the following range of heads accommodate specific fitments - like pre-1992 where by-pass hoses and heater take-offs on the clutch end of the head are used and post-1992 where neither of these exist, and on SPi (single point injection) heads where they don't usually have a threaded hole for the temperature sender - in reality it is easy to convert almost any of them to fit any other engine since holes are easily blocked off - or by-pass hoses not used, water pumps blanked off and drilled thermostats fitted (see articles on cooling/engine transplants). A list of which is what and what to do to each to convert is at the end of this article.
For more in-depth descriptions of the head specs, see article 'Cylinder head - About Min Tec Heads' - basically the valve sizes used have been decided on after extensive and in-depth flow test...
Distributor - Initial ignition timing set-up.
Any deviation away from the original standard engine specification, or where a dizzy from another source is used in the engine you have, the ignition timing will generally be different from that set by the manufacturer.
Terminology - Dizzy - Distributor TDC - Top Dead Centre BTDC - Before Top Dead Centre ATDC - After Top Dead Centre CR - Compression Ratio
Tacho - Tachometer, rev counter (not to be confused with Mexican food delicacy!) Vac - vacuum (pipe, unit, etc.)
Any deviation away from the original standard engine specification, or where a dizzy from another source is used in the engine you have, the ignition timing will generally be different from that set by the manufacturer.
Engine - 998 tuning, further options
Following on from the easily bolted on performance enhancing components out-lined in the stage one section, we need to consider where to go to get more power output.
Terminology: MSC/MM - Mini Spares Centre/Mini Mania BBU - Big Bore Unit (refers to all 1275cc-based units) SBU - Small Bore Unit (refers to all sub-1275cc units, here the 998) BHP - Brake Horse Power CR - Compression Ratio
To improve engine out-put, you need to increase the engine's 'breathing' ability. The stage one kit deals with all the easily bolted-on external parts, and represents the best increase for investment. From here on in the power increases will cost commensurately more money. Power production of any engine, once the 'breathing apparatus' (induction/exhaust system) has been dealt with to cause no restriction ...
Engine - Identification data
If you have the engine tag still attached to the engine - just in front/below the thermostat housing - or perhaps the original engine number in the log book then the following should help you determine which engine you have. For Metro units, see 'Engine - Metro identification data'.
Original engine identification numbers
850cc
8A Austin up to 25000
8MB Morris up to 25000
8AM Austin & Morris 25000 onwards
8AH Austin & Morris Automatic
8AJ Austin & Morris closed circuit breathing
8AK Austin & Morris automatic with closed circuit breathing
8WR Wolseley Hornet & Riley Elf
8AC Moke
85H/101 All variants 1969 onwards
Note: third suffix letter denotes compression type, L = Low, H = High, e.g. 8AM/U/H101 denotes high compression.
Engine - Metro engine identification data
The widespread and prolific fitment of Metro engines into Minis - usually those endowed as standard with small-bore (850/998/1098) engines - practiced in the UK has been spreading to many other countries worldwide.
So it's not surprising that the most commonly asked question has also become more prolific concerning the fitment of said engine - apart from actually how to manage the transplant and the differences in the installations, covered in articles relevant article on this site - is just which type of engine the individual concerned has bought or what they already have fitted to their car and is it worth keeping or junking. One initial question I pose often draws a pregnant silence whilst said inquiree scrambles their brains trying to find an answer for. Following that protracted pause, 'I dunno' is the usual answer. I then have to get into a lengthy explanation as to how to determine what said engine is.
Engine transplants - Ancillary parts
Engine mountings are a whizz to fit as the Mini ones fit straight onto any of the other units. Just remove the Metro/AA/1300GT ones and swop the mounts over from the Mini unit. If they’re split, fit new ones, they’re cheap.
Terminology - BBU - Big Bore Unit SBU - Small Bore Unit
NOTE: This information covers transplanting large-bore engine units into small-bore engined Minis. For further information for exact differences between pre-A+ and A+ units, see relevant separate article.
Engine mountings and steady bars. Engine mountings are a whizz to fit as the Mini ones fit straight onto any of the other units. Just remove the Metro/AA/1300GT ones and swop the mounts over from the Mini unit. If they’re split, fit new ones, they’re cheap. If using the AA/1300GT unit - it's advisable to cut off the 'wings' on the front plate that carried the engine mounts on the radiator end.
Lubrication - Oil, what it does and how
It's criminal. Folk spend fortunes putting together super-sonic motors, only to skimp on the oil they use. Why? Oil's oil right? Wrong. Even if it's a standard engine, it deserves TLC considering it's extremely hostile working environment.
Oil is literally the engine's life-blood. The opening few sentences are astonishingly true. Oil isn't there just to prevent all metal components within an engine fusing together in the first few seconds of running, creating a total melt down of Chernobyl proportions. It's an intricate blending of chemicals to protect the engine as a whole.
The most commonly uttered statement about engine wear is most wear occurs within the first 10 minutes from start up when cold. True if cheap chip fat oil is used.In performance and race engines, a considerable amount of wear is created by heat, load, speed, and pressure. Again, cheapy oil won't give protection here.
Lubrication - Temperature critical
The correct running temperature of the oil is perhaps even more important than the water/coolant temperatures - so let us consider how to control them.
Mainly because it seems to be the most misunderstood of the whole process, and oil cooler fitment almost a reflex when over-heating occurs where a tuned engine of any type is concerned. And in many cases on standard production road cars for that matter.
Almost since the appearance of the immortal Cooper S, fitting an oil cooler has been the essential thing to do to any tuned Mini without any comprehension why. The original fitment was necessary because oil and bearing technology wasn't too advanced. Asking an oil of yester-year to cope with lubricating an engine at racing speeds, and a gearbox pushed their performance to the edge of their all too narrow capability, so extreme control over their working environment was essential for reliability. Hence oil cooler fitment.
C-AHT136 - TPi BUDGET UNLEADED STAGE 2
(ROAD ROCKET) LARGE-BORE HEAD.
Modified to give maximum performance gain for cost. Combustion chambers, inlet and exhaust ports extensively re-worked. Smoothed finish in ports - not mirror-finish polished to minimise drag. Multi-angle valve seats in head. Super-quality MG Metro valves modified to increase airflow. Combustion chamber volume used to give slight static compression ratio increase over standard. Head mods employed greatly increase volumetric efficiency, boosting actual running (dynamic) compression ratio.
C-AHT88 STAGE THREE SPEC SMALL BORE CYLINDER HEAD
Modified to give maximum performance gain for cost. Exhaust seats Latest spec inserts for lead free fuel Modified to give maximum performance gain for cost. Combustion chambers, inlet and exhaust ports extensively reworked. Stone-ground finish in ports promotes ultimate fuel atomisation.
C-AHT133 - Pre 1992 BUDGET UNLEADED STAGE 2 (ROAD ROCKET)
Modified to give maximum performance gain for cost.
LARGE-BORE HEAD, 24.5c chambers for large bore motors.
Inlet Valves: 35.6mm(1.401") dia. Original equipment type P/No. TAM1059 Exhaust Valves: 29.2mm(1.150") dia. Original equipment type P/No. TAM1061 Exhaust seats: Latest type Beryllium-based for lead-free fuel P/No. TAM2069 Valve Guides: AE Hepolite cast iron P/No. 12G1963 Valve Springs: Nominal 180lb. Max actual valve lift 0.400" P/No. C-AEA526 Stem Seals: Latest 'top-hat' design with tensioner springs (inlets) P/No. ADU4905
Chamber Volume: Nominal 21cc Modified to give maximum performance gain for cost. Combustion chambers, inlet and exhaust ports extensively re-worked. Smoothed finish in ports - not mirror-finish polished - to minimise drag. Multi-angle valve...
C-AHT135 - Pre 1992 BUDGET UNLEADED STAGE 2 (ROAD ROCKET) LARGE-BORE HEAD.
Modified to give maximum performance gain for cost. Combustion chambers, inlet and exhaust ports extensively re-worked. Smoothed finish in ports - not mirror-finish polished - to minimise drag. Multi-angle valve seats in head. Super-quality MG Metro valves modified to increase airflow. Combustion chamber volume used to give slight static compression ratio increase over standard. Head mods employed greatly increase volumetric efficiency, boosting actual running (dynamic) compression ratio.
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