Camshaft Design

Elgin Cams is a company that is a direct descendent of such famous California specialists as Isky, Delong, Winfield, etc. etc. Elgin has taken the art of cams into the science of the '90's. Computer designed and handcrafted workmanship guarantee a first class camshaft. Custom designed cams are a specialty. Part No Applications: CAM001, CAM002, CAM003, CAM004, CAM005, CAM006, CAM007 Elgin has made cams or sold his design to General Motors, Ford Motor Co., Nissan Corp., Zakespped International, Porsche Motor Sports, Winston Cup "Engine Builders. Elgin has the largest percentage of cams used at the SCCA Runoffs from GT-1 to Formula-V. He also has provided original or new technology for antique and vintage racers. Much information has been recorded about the four stroke internal combustion engine and yet only a small percentage of people really understand how it works and fewer people know how to modify an engine to suit their needs.

Rocker gear - General compendium

Whether you’re building a solid road performer or fire-breathing monster, the main goal is to improve air/fuel flow into the engine. The more you can get in, the more power you can get out. Cheapest chunk of power improvement comes from sorting the asthmatic manifolding and exhaust by applying a stage one kit. Then what? Considering the ‘get more in to get more out’ theme, the main restriction - all else being equal - is the valves and their behavior. How big they are, how efficient they are and how long they’re open for determines how much gets in with each gulp each bore/piston makes. Modified cylinder heads are popularly next, although it has to be said that although a well modified cylinder head will improve performance, the gain against cost is nowhere near that given by the ‘stage one’ kit application. A good stage one kit’s improvement verses cost is around £12.50 per 1 hp, a decent modified head typically £30 per 1hp - dependent on application. Hmm.

Engine - 998 Tuning, Bolt-ons

The 998cc engine is a very robust and tunable unit. It is also the most common engine found in standard Minis. See bottom for useful part numbers Terminology: MSC/MM - Mini Spares Centre/Mini Mania ID - Inside Diameter OD - Outside Diameter 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 LCB - Long Centre Branch Despite the lure of the much-advertised 1380cc alternatives, many simply want to get a little more from what they have at reasonable outlay. The single biggest restriction on any standard Mini is the 'breathing apparatus' - anything that is connected to the induction and exhaust systems. The standard exhaust being the biggest culprit - it is desperately restrictive in the name of noise suppression and cheapness of manufacture. Oddly enough it also increases fuel consumption when tested over a better designed, fre

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...

Cylinder head - Suitability basics

Whatever else owners do to their Minis by way of interior/exterior modifications or none at all, a very large proportion desire and search for an increase in engine performance.

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. Although the induction/exhaust system plays an important part, there are effectively two major factors that dictate performance increases - the camshaft and cylinder head. The induction and exhaust elements (stage one kits, exhaust systems, etc.) and camshafts are covered in various other articles in my 'Corner'. So here we'll have a look at cylinder heads and dispel some of the myths and legends surrounding them.

Cylinder head - Torque-down and head gasket problems

This is to help those floundering in an unknown sea of techno-babble and 'magical' cures… Part No Applications: C-AHT288, CAM150, CAM151, TAM1617, CAM4545, 51K1193, TAM1521, GEG300, C-AHT188, C-STR1057, A regular visitor to the message board, and something I am asked frequently about in my other incarnations for other technical media. Generally when something has gone badly wrong! Many folks have just as many ways of dealing with the following subjects - all can and will claim their way has worked for them for the proverbial millennia - so a few words as a basic reference and guide as I see them; we all know there are always exceptions to the rules. This is to help those floundering in an unknown sea of techno-babble and 'magical' cures…

Engine - 998 tuning, bolt-ons (stage one)

The 998cc engine is a very robust and tunable unit. It is also the most common engine found in standard Minis. Despite the lure of the much-advertised 1380cc alternatives, many simply want to get a little more from what they have at reasonable outlay.

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.

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 transplants - initial information and engine choices

Is this familiar? - You take the small one out; you put the big one in. In, out, in, out, shake your fist about, you do the hokey-cokey and you turn around, that’s what it’s all about...

Terminology -
BBU - Big Bore Unit
SBU - Small Bore Unit
Bodge - English term for 'make do' engineering- assured to fail at an in opportune
Moment.
Dizzy - Distributor

NOTE; this information is largely for transplanting large-bore units into small-bore engined cars.

Is this familiar? - You take the small one out; you put the big one in. In, out, in, out, shake your fist about, you do the hokey-cokey and you turn around, that’s what it’s all about...kinda sums up the situation many folk find themselves in when attempting to endow their beloved Min with a more impressive turn of speed.

Exhaust - CAPTIONS for manifold article pictures.

Standard cast iron manifolds

Pic 1.
Standard cast iron manifolds - Mini on left, Metro ‘LCB’ type right. One major benefit of cast iron is noise absorption. Tubular steel amplifies resonance caused by exhaust gas phenomena. Stainless steel being THE worst.

Pic 2.
Cooper Freeflow. Careful, exquisite forming of primary pipes and neat welding ensures un-interrupted flow of exhaust gases. Medium length primaries promote performance where mild cams are used.

Pic 3.
Ubiquitous LCB. The two outer ports are connected by short primaries joined to a larger secondary pipe, the centre port getting one pipe all to it’s self. These equally sized pipes continue down under the car, ending in a ‘Y’ piece to join them to the system.

Exhausts - RC40, Millennium and others tested

The recent rolling road re-test of the 1275 engine build I did saw an opportunity to do some exhaust systems testing.

I had noticed a few years back that the RC40 was being manufactured by a different process than the originals - giving rise to a change in the shape of the bends applied to the system. I had wondered if they would be causing a restriction at all - but hadn't had the opportunity to test it. The lack of expected power from the aforementioned engine lead me to investigate all possible angles from the tyre contact patch to the carb mouth. I found nothing that explained the 14 or so bhp I was 'missing'. After some application of the old grey cells I mentally narrowed cause down to one of two things - either the piston oil control rings were still causing excessive drag (75% of all internal friction of an engine is generated by the piston rings) or perhaps these new bends in the venerable RC40 were indeed causing a power loss.

SU Carbs - Poor idle quality

Something that crops up when any modifications are made to an engine - mainly in the form of improving induction and exhaust capability - is that of idle quality.

After applying aforementioned freer-breathing products to enhance power output, many complain that no matter what - including post rolling-road tuning - they can not get a satisfactory, steady idle setting. And this after checking for manifold/gasket air leaks and spindle to carb body play (usual suspect as the spindle wears quite dramatically over several thousand miles). There is one thing that is often over-looked - the air valve found on many later model cars. This sprung-loaded air valve is built into the butterfly, sometimes called a 'poppet' valve or anti-dive valve. It is primarily there to reduce emissions when the engine is on the over-run - closed throttle at speed, i.e. anything other than at idle and gearbox in neutral.

C-STN17 - MINI SPARES STAGE ONE KIT (998cc only)

Beware: Instructions must be read carefully.

Although the 998/1300 stage one kits are bolt on parts easily fitted by any person with mechanical knowledge, the following must be understood.

C-AJJ4064 – 8 PORT CYLINDER HEAD

The combustion chambers are left in a basic shape only with a nominal 16.4cc which allows enough metal for those with the latest advanced ideas of shape to apply them and create the correct compression ratios for the desired use.

Valve and seat material specification allows use of unleaded fuel. Thoroughly clean the cylinder head before final assembly. Check that the small circlip is in the correct position in the valve guide at a point where the guide protrudes through the cylinder head beneath the valve seat. Place the valve spring seat over...

C-STN20 SPI PERFORMANCE KIT and C-STN20BUDGET KITSINGLE POINT 1992-1996

This kit has been specifically designed to work with the factory fitted existing single point engine management system. No modifications are necessary

Please beware that if prolonged speeds of 100mph are envisaged the engine may run lean and could eventually lead to engine failure. Power output figures of around 80bhp are normally expected after fitment but is dependant on the original engine build (rolling road tests have consistently shown 20-25% increases).

Figures confirmed by Swiftune Racing. Extra BHP can be obtained with professional air box modification. Further power increases would necessitate modifications to inlet manifold and use of a tubular steel LCB exhaust manifold. These performance figures apply equally to both kits and the only difference is the material of the valves and the different type of 1.5 rockers used. The budget kit uses forged rockers and includes 4 extra washers to shim correct alignment over the valve stems. Fit 2 of AEG168 washers b...

Fitting instructions for Remote Vacuum Servo Units Types 6 and 7

General fitting instructions

To ensure correct installation of the AP Braking remote vacuum servo unit, thoroughly read and adhere to the fitting instructions prior to carrying out any work on the vehicle. Introduction The vacuum servo unit is incorporated into the hydraulic braking system, remote from the master cylinder, as an intermediate stage operating between the master cylinder and the brake assemblies. The two main parts of the servo unit consist of the vacuum servo mechanism and the hydraulic slave cylinder assembly.

These component parts are bolted together so that the slave cylinder piston is in line with, and is operated by, the servo push rod. A plastic no-return valve is fitted into the vacuum shell and an integral air cleaner is incorporated to prevent foreign matter entering the air control valve chamber. The servo unit is designed to give no assistance with very light brake application. In the absence of servo assistance due to loss of vacuum, an unres...

ARDEN 8 PORT ALLOY HEAD

Still produced from the original tooling purchased in 1990 from Jim Whitehouse these Arden alloy 8 port heads were never a straight bolt on conversion. Designed with racing in mind it was developed in 1966/7 to take full advantage of the change to Group 2 racing regulations which allowed more freedom in cylinder head design.

Minispares New Arden 8 Port Head.

The original Arden 8 port head tooling was purchased from Jim Whitehouse in 1990, sadly genius Jim died in 2008 aged 89. Designed with racing in mind it was developed in 1966/7 to take full advantage of the change in Group 2 racing regulations that allowed more freedom in cylinder head design. This revolutionary 8-port concept took the world by storm when Alex Poole took the 1000cc class and British Saloon car championship series outright in 1969 in an Arden Equipe team 970cc Cooper S with the 8 port head and Tecalemit fuel injection.

Cylinder head 2022