Concerned about fitting up-rating parts to injection engines? A short while ago I had several conversations via e-mail with folk abroad who were a little concerned about fitting up-rating parts to their injection engines - like one of the many 'GSi' tuning kits available. A rumour had been put about that fitting this kit caused engine damage. Closer questioning culminated in the rumour saying that the high lift (1.5 ratio) rockers were causing camshaft and valve/guide damage. You know me - I can't let things like this alone until I find out the root cause. After some more digging and goading, I believe I've found the problem.

Cam damage is usually caused by something amiss in the valve train - obviously. Since the engines concerned were as they came from Rover and had done many thousands of miles without issue, it had to be something to do with these kits. Read more

Having decided on or even implemented a course of action to bolster the performance of your Mini’s engine, maximising it’s potential should encompass a good look at the gearbox. Read more

Gearbox - Fomulae for FD/Tyrespeed and Gear Ratio Calculation

Basic rule to remember is ratio is established by dividing tooth count ondriven gear by the tooth count on its driver. To work out overall gearbox ratios you also have to establish the constant ratio.

Terminology -
FD - Final Drive (diff ratio)

Formula : 60,000 FD (Final drive/diff ratio) x wheel rev per mile.

Calculation for establishing vehicle speed for different final drives.
Formula These are for common tyre types, and accurate enough for assessment - a combination of using industry standard for theoretical calculation, actually measured assortment of wheels/tyres, and calculated averages! Applying Read more

GEARBOX - standard production gearbox types

The first Minis rolled off the production line with a three-syncro gearbox, first gear as explained earlier was still a hit and miss affair.

Terminology -
FD - Final Drive

NOTE; A 'high' or 'low' ratio gear is in reference to it's performance, not it's numerical number. To illustrate - a 'high' FD ratio will give 'higher road speed', but will have a numerically low figure. A 'low' FD ratio will give lower road speed, but have a numerically high figure. A by-product of this will be reduced acceleration capability on the 'high' ratio, increased acceleration capability on the 'low' ratio. The main gearbox gears work in the exact same way.

I’m sure we’re all aware of Sir Alec Issigonis’ brilliant solution to the gearbox location in the Mini - just fold it up underneath the engine, simple. Following is a résumé of the production gearboxes to date. Read more

Thread Locking Compounds - Application

This is the frequently abused and mis-used stuff dolloped on to bolts/nuts to stop them coming undone. Having seen and heard of many horror stories concerning this stuff, I thought a few words of caution and common sense wouldn't go amiss.

There is a plethora of types on the market with no easy reference as to which to use for what application except in certain cases. Loctite have a very useful guide, their dealers generally able to help with choosing which is best for any given application. The trouble comes when folk buy stuff unwittingly from their local 'do it all' motorist/car spares place. Good stuff is expensive, and it doesn't go all that far. But at least it does its job when used in the correct applications. Unfortunately many buy a cheaper variety with not quite the same application strength, and then apply twice as much hoping it will do the job. It doesn't. Read more

Thread Locking Compounds - Application

This is the frequently abused and mis-used stuff dolloped on to bolts/nuts to stop them coming undone. Having seen and heard of many horror stories concerning this stuff, I thought a few words of caution and common sense wouldn't go amiss.

There is a plethora of types on the market with no easy reference as to which to use for what application except in certain cases. Loctite have a very useful guide, their dealers generally able to help with choosing which is best for any given application. The trouble comes when folk buy stuff unwittingly from their local 'do it all' motorist/car spares place. Good stuff is expensive, and it doesn't go all that far. But at least it does its job when used in the correct applications. Unfortunately many buy a cheaper variety with not quite the same application strength, and then apply twice as much hoping it will do the job. It doesn't. Read more

Injection - Tuning Update 03.14.03

This program of development embarked upon by myself and colleague Mike Barratt (MBE, Lincoln 01522 545189) was instigated by Keith Dodd, owner of Mini Spares centre. His instructions were for us .... Read more

GEARBOX - Limited Slip Diffs, what's available.

‘Salisbury’ is the word banded about by most un-enlightened folk when discussing LSDs for Minis, mistakenly believing the word covers all Mini orientated LSDs. This is grossly incorrect. Terminology - LSD - Limited Slip Differential The ‘Salisbury’ was designed in the ‘50s at a time when racecars were a good deal less sophisticated than today. Tyres were usually cross-ply with severely limited grip due to poor compounds developed ostensibly for rear-wheel-drive cars; the front wheel drive of the Mini being a rarity. And tracks were more than a little ‘bumpy’. Agriculturally built cars needed an LSD designed along similar lines; enter the Salisbury - effectively developed from a tractor diff. High static pre-loads were more than common to help compensate for severe short-falls in chassis, suspension, and tyre design. To all intents and purposes the diff was practically locked up, making the car a real beast to drive. Read more

Gearbox - Limited Slip Diffs, What they're about

Modified engines producing more power generally induce owners to drive with greater verve, particularly when competing in one of the many motorsport disciplines. Terminology - LSD - Limited Slip Differential In fact this isn’t isolated to modified Minis. Owners of relatively standard machinery competing in a discipline or merely out on a country lane blast are subject to the same determination. The more verve/determination applied, the more of a struggle keeping your Mini on the designated track becomes. Generally the problem is down to grip - or more precisely the lack of it. Suspension modifications and extensive twiddling of geometry settings can provide improvements in stability, both for straight lines and turn in/mid corner performance. But even throwing bucket loads of cash at super high grade dampers, and the odd arm/leg/lung handed over to ‘professional’ chassis tuners doesn’t solve the particular grip problem we’re interested in here - corner exit/acceleration grip, or traction as it’s more commonly referred to. Read more

Flywheel - Pre-Verto Types

The early spring-type clutch flywheels are of no use except where total originality is required on a concours car. The taper is too small and diaphragm pressure ring non-existent. No use to man nor beast. Part No Applications: C-AEG421, C-AEG420, C-AEG619, C-AEG620, 2A3657, 2A3658, 2A3659, 2A3512 With the exception of the fact the two-piece flywheel is two pieces bolted together - this and the later one-piece cast item can be treated as the same thing. They will universally fit all transverse engine cranks from 1964 onwards, so that should be easy enough. If all you can get is the hulking great 1300 type, then this too is as universal to fit, but I highly recommend you get that extra cast lump machined off of the outer edge as a bare minimum. Further lightening of these cast flywheels is possible by having metal machined off of the diaphragm side, from the outer edge of the diaphragm pressure ring outwards. Read more

Flywheel and Pressure Plate - Effects of Lightening the Assembly

How does this affect performance? Not as many folk believe, that’s for sure. For a start, lightweight flywheel/clutch assemblies don’t necessarily give rough running at idle, particularly where a performance cam is used. Nor do they make the engine produce MORE power. BUT they do make a difference to the ACCELERATIVE performance of the car - and that is what we’re most interested in most of the time! Basically, the engine sees the car as a weight to move, via the gearbox. The combustion pressures created by your common or garden suck-push-bang-blow engine have to accelerate not only the mass of the car as a whole, but the mass of the engine internals too. However, the engine can only accelerate the car at a certain rate with what power is left over after the engine internals have consumed their share. The lighter the rotating and reciprocating parts are made the less power is consumed by them, leaving more to actually accelerate the car. Read more

Engine - Running in Procedure

This is another of those subjects that crops up on the message board frequently. I am constantly surprised by the number of engine builders - or people who charge other folk for building engines at any rate - that never hand out such an information sheet. It seems pretty daft to me that having taken a wad of money off of a customer for an engine you've lovingly put together, you'd want to help that person get the very best out of the engine. And the running/breaking in procedure is absolutely crucial. It at least ensures no damage is incurred when the engine first bursts into life. A collection of the usual suspects have explained their own methods on the board, along with various others - many of which probably work just as well for them, a few which are down-right dubious. Following is a sheet I administer with every customer engine I build. Read more

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, free-flowing unit, so this is the place to start - NOT I stress the intake which is where many start in the belief that's the way to go. Read more

Engine - 1098, Initial Tuning

The 1098 (1100) engine has had a lot of bad press over the years - largely because of early experiences when trying to tune the motor brought about problems with the then standard components available - they simply were not up to taking any real punishment as experienced in racing.

See bottom for useful part numbers.

This fallacy was handed down generation to generation like some scary bedtime story. Those that have used the unit in more recent years, employing more capable componentry know what a demon motor this can be. Following is an initial look at what it will do with a little modification - the results compared directly with it's smaller brother the 998 for illustration of the potential.

Abridged History
When the Mini was first conceived it ustilised a de-stroked version of the then quite remarkable 948cc A-series engine. Read more

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 circuit breathing 9AE Wolseley Hornet & Riley Elf Mk3 99H/-/101 on Wolseley, Riley, Mini 1000, Clubman1000 1970 onwards and Mk3 with dished piston Read more

Crankshaft - Standard Production Crank Identification

Yes, contrary to what many say/express, all cranks are forged. None are cast. They wouldn't last 2 minutes in an engine if they were cast - they'd be way too brittle. Below is a list of crankshaft identification data by forging or stamped numbers - yes, contrary to what many say/express, all cranks are forged. None are cast. They wouldn't last 2 minutes in an engine if they were cast - they'd be way too brittle. The differences are in the material used, finish machining detail and any heat treatments applied. It is by no means complete and utterly correct/infallible since Austin/Morris, British Leyland, Leyland cars, Austin Rover, rover, et al were seriously prone to not adhering to specifications and applications lists. But it is better than nothing at all! 22A62 850cc - Early type with oil feed for primary gear, 1.375" dia. tail 22A63 850cc - Early type with oil feed for primary gear, 1.375" dia. tail Read more

Distributor - Electronic Ignition

Since the A-Series has such an efficient combustion chamber design, the standard points set-up is perfectly capable of providing sufficient sparks for effective combustion when new. And this is the problem. They require regular servicing to maintain maximum performance. This can be a chore, so is generally neglected. And it doesn't take long before deterioration seriously affects performance. Points bounce is also a problem on high-revving race motors.

Deterioration of the points set-up can be caused by several factors - wear and tear on the dizzy spindle bearings creating 'wobble', electrical erosion of the points, and wear of the points cam heal. All have the same effect - dwell angle alteration. This in turn reduces spark effectiveness. The consequences are a loss in power and economy, poor starting performance, and general poor running.