The fuel situation seems to be worsening at a great pace these days. And as is exhibited by the questions that appear on the message board many folk are confused by what they can and can't do, and what is best to do as far as race engines go.

Many have posted (particularly from the States) that nothing need be done - just run on unleaded. They've been doing this for years and never had any problems. I have trouble believing that in the face of what I know and have investigated - so here's what the score really is.

Years ago this stuff called Tetraethyl lead was originally conceived as an octane enhancer. It was soon discovered, however, that the metallic oxides produced by the combustion process formed a protective coating on the valves and seats. This coating prevented micro welding of the valve seat to the corresponding seat in the head under high temperature operation.

Any dizzy can be set to get maximum power. No problem. Unfortunately that's only one spot on the whole power curve/rpm range. If the curve isn't right elsewhere, the engine will be either loosing power - in some instances by substantial amounts - or detonating its self into oblivion and a costly re-build.

Terminology -
Dizzy - Distributor
CR - Compression Ratio
VE - Volumetric Efficiency

Large-bore engines are less fussy about exacting ignition requirements than small-bores. The 1100-type being the most difficult to get right, with very particular requirements mid-range when tuned and worlds apart from large-bore curves. This should be remembered when swapping distributors from one engine to another. An 1100 dizzy in a 1275 will at run OK, but a 1275 in an 1100 can be courting disaster.

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.

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… Read more

Since the reasonably recent publishing of a certain Mini tuning, performance and maintenance guide that has strangely coincided with a batch of new readers/devotees of a certain prolifically quoted 'bible' on A-series engine modifications - the subject of all things cylinder head have bounced into the fore once more.

Something I was heavily canvassed over at this years (2003) Mini in The Park event whilst doing duty as Mini 'agony aunt' and 'doctor'… In particular the subject of the combustion chamber was foremost in discussion since the aforementioned 'guide' exhibited a number of wildly different chamber profiles with very little in the way of supportive technical information. Now, I have considered the pros and cons of doing this missive. On one hand, I am not out to increase sales of said guide since I'm not one of its supporters in any way. On the other I am certainly not attempting to belittle the efforts of the featured company as they have long been at the forefront of performance A-series engines and components... Read more

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

I'd like a pound coin for every time I've been asked about what these are all about and why they are used. Folk seem to hold them in some kind of awe - but they are very simple. Part No Applications: DLB105, GCL111, GCL143, GCL132 The ballast resisted ignition system was - I believe - developed by Ford when they were experiencing poor starting on a certain prodigiously-used 4-cylinder engine. To get round the issue of the massive current drain caused by the starter motor functioning, the ballast-resisted system was designed. When you hit the starter button/key, a massive drop in available current to the coil occurs as the starter motor does its thing. The colder the weather or the more worn the starter motor, the more current it draws, the less there is passed to the coil to instigate ignition.The ballast-resisted system utilises a 6 (commonly called the 'cold start' system) or 9-volt coil instead of the older style 12-volt item. Read more

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 standard. Read more

The specter of 'unleaded fuel only' - instigated in UK on January 1st 1999 and seemingly from decades ago across the rest of the world - seems to be forcing more and more folk into frightened, panic orientated action. And Mini owners are featuring heavily in this. See bottom for useful part numbers. The situation not at all being helped by all sorts of conflicting information from 'leaned' sources, such as lead levels in humans has declined greatly since 1935 - despite the rapidly expanding ownership of petrol-burning vehicles. And benzene and toluene used in unleaded fuels are cancerous. Still, the powers that be are relentlessly forcing through the 'no heavy metals in fuel' bills, not being at all put off by such trivia. Not surprising bearing in mind the complete debacle on the catalytic converter front - the type decided on for world wide and universal use was developed and tested in California! Read more

During a discourse with the editorial staff at Mini Mag, it was decided the build feature presented an ideal opportunity to demonstrate just exactly what such an engine build is capable of in days where it's generally believed you have to have an all-singing, all-dancing 1380cc engine to have an enjoyable road burner - leaving those with very limited budgets a little depressed. During a discourse with the editorial staff at Mini Mag, it was decided the build feature presented an ideal opportunity to demonstrate just exactly what such an engine build is capable of in days where it's generally believed you have to have an all-singing, all-dancing 1380cc engine to have an enjoyable road burner - leaving those with very limited budgets a little depressed. So the idea was to finish the engine off using a relatively 'mild' specification to maximise drivability. The camshaft used was the fantastically versatile Swiftune Racing SW5 profile that provides drive from nowhere up to 7,000rpm - depending on the finished spec - with minimal hydrocarbons for emissions testing. Read more