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.

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.

SU Carbs - HIF, a more finely honed instrument

Modern technology continually sweeps its ever-growing arm across all manufactured products and the SU was no exception. From closer scrutiny, and more demanding emissions control the HIF variant was born. So what have they done to improve it over its predecessor - the HS - and is it worth hanging out for? PROS. Integral float - the 'IF' in the new type number HIF. The previous H and HS type carbs with their side-mounted remote float bowls worked fine until used in racing where serious cornering speeds generated enough G-forces to lean-out the fuel mixture. The remedy was to fit a spacer between the float lid and float bowl to raise the fuel level held in it. OK when running, but at idle and rest, fuel would bubble out of the jet - causing bore washing, poor pick-up, and horrendously rich CO mixtures at idle! Fitting the float integral with the carb, directly below the jet hole (port/orifice), eliminated this problem. Jet temperature compensation - This was first aired on HS types

C-AHT770 & C-AHT770A Inlet manifold information

These single SU carb manifolds were developed to provide optimum airflow and air speed for the vast majority of road-used cars. The development program saw a significant increase in efficiency following production to the point where they are the best 'off the shelf' manifolds on the market for a majority of applications, including motorsport where only a single SU is allowed, yet not at extreme expense since sand casting methods were employed to keep costs down.

C-AHT770 & C-AHT770A

These single SU carb manifolds were developed to provide optimum airflow and air speed for the vast majority of road-used cars. The development program saw a significant increase in efficiency following production to the point where they are the best 'off the shelf' manifolds on the market for a majority of applications, including motorsport where only a single SU is allowed, yet not at extreme expense since sand casting methods were employed to keep costs down.

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...

Historical Article - October 1993 - Calver's Clinic

Calver's Clinic There are many small side issues, problems, technical hints and general advice that do not warrant a full story, but never the less are important enough to cover. To this end I will be using "Calver's Clinic" as a regular feature in Mini T ech News to cover such things.A friend and colleague of Mini Spares runs the "Mincomp Mini " in America. His name is Bill Gilcrease - those of you who have read Mini Tech News 1 may recall that he was in this issue covering his escapades at the USA run-offs in Atlanta

Historical Article-August 1994- 8-Port

8-Port The thick deck Cooper S cylinder block was bored to 1358cc.The EN 40B crankshaft was our very special Jaguar(fouring car design, using the largest possible counter weights we could swing in the block.

Historical Article-August 1994- 8-Port

8-Port The thick deck Cooper S cylinder block was bored to 1358cc.The EN 40B crankshaft was our very special Jaguar(fouring car design, using the largest possible counter weights we could swing in the block.