Calver's Clinic

COOKING OIL
This engine oil thing seems to have caught people's attention - which is good as there is nothing like awareness of what is good for your engine. Having done the 'Life Blood' article in Minitech News 6, and what oils to avoid in Mini Tech News 7, I have been swamped with questions with regard to oil cooler sizes required. Well, you will be surprised to hear that on a vast number of road cars - no matter how modified - an oil cooler is large unnecessary if a decent quality oil is used, and changed at reasonable intervals.
As purchase of an oil cooler and complimentary fitting kit is not exactly a cheap option, and fitting can be a real pain (especially onthe newer cars with preengaged starters, bigger alternators, etc.), it is sound advice to establish exactly what your oil temperature is. Fitment of a gauge is easier and cheaper, and will need to be retained if a cooler is found to be necessary. The sensor should be fitted to the oil pipe going to the oil filter housing, as it is the temperature of the oil as it is fed to the crank at that is important, not the sump temperature. The ideal operating temperature is 80 to 90 degrees C (176 to 194 degrees F), although most decent synthetic oils will be fine up to 120 degrees C (248 degrees F). Now that allows for a fair range of operating temperature, you can seen why an oil cooler is usually unnecessary .
It appears that many of those that have posed this question believe an oil cooler is a necessity because they always used to fit them, and the Cooper'S' had one as standard. But that was a milliena ago as far as scientific development is concerned - and particularly where automotive lubrication is concerned. Oils of yesteryear were not particularly good in as much as their ability to deal with broad operating temperature bands are concerned - hence there were a myriad of single viscosity oils about, ie Castrol R30, R40, RSO etc., etc. Bearing in mind that the Mini's gearbox thrashes the living daylights out of the oil before it gets near the engine, these old oils were breaking down way too soon - so slap on an oil cooler to ease the situation. Modern oils are far more efficient, effective, and durable given modern technology. essentially what I am pointing out here is that modern oils are far less prone to premature degradation. Running an oil too cool is every bit as bad as running too hot - too cool and it will not absorb the combustion byproducts it ought to be, and will not vaporise those that have along with any water in the oil (absorbed whilst the engine is cooling down), too hot and it loses its lubricity. A good example of the 'too cool' syndrome is the milky coloured
deposit found in the rocker cover of those cars only used on short journeys (more applicable to older cars with 82 degree or less thermostats). The oil is not getting up to temperature so can not vaporise these deposits.                                                                                                                                                                                                                     So if you think you need to fit a cooler, check the oil temperature FIRST.

AND TALKING ABOUT
KEEPING YOUR COOL ...
Another much vented subject, engine cooling. This appears to be another subject that is misunderstood and problems misconstrued. I am amazed at the number of oils that have a cooling problem, but a new radiator (usually our special uprated types), fit it and find they still have a problem. True, most of these enquiries are about modified engines, but there are some basic points to check irrespective of engine size before laying out a load of dosh on a new rad.
Ignition timing. Yep, this can enormously affect the engine's running temperature. Take the dizzy out, remove the cap, rotor and base plate, and make sure that the advance  mechanism (and vacuum advance mechanism) is functioning properly - i.e. is not jammed up or sticking. Stick it back in and set the timing to the manufacturer's recommended figures. If in a modified engine, ask someone with experience in tuning performance A series engines for a starting point. If the dizzy is of a modified type, check for suggestions from the  manufacturer.
Now, get the thermostat out to see if that is stuck shut. Easy this, boil a kettle, and chick the 'stat into the water. If it pops open, it's OK. If not, buy a new one. Oh, I forgot to say it could be possible that there is no 'stat in there {yes, people actually leave this out thinking it will help!} - in which case put one in. If the engine has no bypass hose between the head and water pump {often blocked off on modified heads}, drill half a dozen 1/8" holes around the outer rim of the 'stat to allow water to circulate before it opens. Alternatively a blanking sleeve can be fitted , but on a road car some control should be maintained over the coolant temperature. Suggest a 74 degree one for well modified engines, 82 for warmed up engines, and 88 standard or economy orientated engines. Always fit a 151b cap (unless you have a really early rad with a shallow neck - in which case you are stuck with what's available).
Radiator time. Give it a good reverse flush out with a hose. that is, turn the rad upsidedown, feed the water in through the bottom hose hole, and the water should flow out of the cap and top hose holes. This should dislodge and remove the build up of any sediment - except in sever cases. You should be able to tell this from what is coming out in terms of crap, or not in terms of water.
Whilst the rad is off, check the fan blade, make sure it has blades on it, and that it is fitted on the right way round. In the plastic fans there are metal inserts where the retaining bolts go through, the side that looks as if it has a washer attached where the bolt heads should sit down on face towards the radiator, some even have an T on them for 'front' {facing the radiator}. If the fan is not on the right way, it will not be sucking air through  the rad as some people think, it will just not be blowing as effectively as it ought to be.
Now try again still overheating or running hot? Now phone your friendly and all knowledgeable Mini specialist for more specific advice. Or why not write in to Minitech News with any further queries? It'll get answered, honest.
THE 'BIG BORE                                                                                                                                                                                                                                               Now I just know this is going to cause a bit of a ruck, but this is a subject that sees plenty of 'air-play' on the Mini Spares hot line. And I quote thousands here - 'Which is the best big bore kit/engine to buy?', meaning 'Whose' of course. Well, I know I am not renowned for my diplomacy on certain subjects but here I will tread carefully. Suffice to say I will outline what to look for.
The initial considerations seems to be price, but the old adage of 'you get what you pay for' absolutely applies here. Competition amongst the main players in the sale of these units has
forced prices to rock bottom, and I have to say that little consideration is given to just how good a deal you are getting from any of these guys. Really. Anyway, I d ig ress on that for
the moment. Er, where was I, oh yeah, so because of this massively discounted price, there are two areas that make up the price. One is the labour that goes into it, the other the physical components.
Easiest place to start is by comparing the type of components used, and just what you get in terms of those parts - ie is a t iming chain included, or a complete timing gear set? Is it single row (Simplex) or dual row (Duplex) type? What type of pistons (see separate section), what type of bearings? etc., etc.
Once that is covered, check out what has actually been done in the way of remachining , heat treatments, etc. Whether the components are washed off/cleaned out and degreased and
painted ready for assembly, threads cleaned, relevant holes counter sunk, etc. The less time spent on this type of preparation, the cheaper the kit can be made. I am not saying you should ask for the build-prep work to be missed off so you can ask for an even lower price, just compare the differences from one company to another.
One last final point is pedigree. Consider the company's background, how long have they been in business, have they a good track record, do they build successful race engines (don't take what the Mags say for granted - unfortunately most of the articles that appear are far from truthful. Ask people who actually compete!                                                      PROTECT YER LOBES
DON'T GET 'EM TORN OFF!!
A spate of cam 'failures ' has prompted this bit. No long stories here, just a few simple guidelines to prevent you folks from scrapping your high performance rootn ' -tootn' rinky dink
mega lift sports camshaft first time you use the motor.
The basic problem is an age old one, if all else fails, read the instructions' (recently shortened by those of us in the trade to 'RTFI' - no prizes for guessing the exact working). It is pretty difficult to get to grips with the thought that folks spend loads of hard earned wonga on a new super trick engine kit, then assemble it w ith reading any of the suppliers guides on how these parts should be fitted. Only as an afterthought are they consulted in earnest when things have gone badly wrong, and prior to a stroppy 'phone call to the supplier of a 'bum' article.
When you put a new cam in your engine ALWAYS use new followers - absolutely NEVER use even slightly second hand ones. When you put the followers in the block, lube around
outside ONLY with engine oil, and make sure they are free in their respective holes. DO NOT use just engine oil on the foot of the follower (where it meets the cam lobe), this is useless - desperately ineffective and runs off if the engine is not used straight away. I personally use anti-scuffing paste on the lube and follower foot, only a smear is needed, but provides
excellent protection and NEVER runs off if the engine is stored for a period. another extremely good lubricant for the job is Torce Oil"s engine building lubricant with MPZ (no, don't ask what it means now- too involved}, I have used it and was suitably impressed.
Nuff said I hope.

PISTON BROKE
Choice of piston for any performance application pops up on a regular basis, and it would seem that there are a couple of engine building/engine kit suppliers that are giving out
slightly misleading information. As this rarely revolves around the 1275 based units in either regular over-bore sizes or big bore conversions, I'll restrict this resume to them.
For regular over engines (ie +20, +40, +60}, there are really a couple of sensible options. AE Hepolite's current range of low drag 'slipper' style pistons are extremely good. Available in a variety of compression ratios, they are well priced. However, they do have their limitations. The 8.0 and 8.8 to t CR versions should only be used in engines rewing to 6,000 max using a CR of no more than 9.0 to t. I have extensively played with these and found that they collapse at anything over this. Not necessarily straight away or completely dropping apart, but
collapse over a period of time due to the crowns not being supported enough. the 9.4 to 1 items are pretty hardy, and will take 7,000 rpm with a maximum of 10.5 to 1. The 10.3 to
1 types are excellent. I have used these in race engines up to 12.5 to 1 CR and 8,300 rpm for safety with no ill effects. Needless to say, the better the quality, the higher the price- but at least the above should give some guidance regarding their uses. They all have an 8.4cc bowl.                                                                                                                       Omega also do a range of regular over bore pistons in both cast and forged. The forged ones are damn near indestructible except in extreme circumstances, but are a little costly for
most road applications. The superb quality cast pistons can not be bettered by any other cast piston, and can be used in everything from mild road to full race - I have run them at close on 14 to 1 CR and 9,500 rpm with no problems. They are available with flat tops, or offset bowl type. Bowl is 5.5cc. Unbelievably they are comparable on cost to the AE low drag
pistons - and represent exceptional value for money.
Big bore wise, there are currently two suppliers. A third has been threatening production, and even has advertised them but I have yet to see a set so I am currently unconvinced about their availability, and therefore their performance. A further sourcehas been set in motion which looks very promising if samples and track record are to go by. As soon as they are available I will be putting them through their paces and duly reporting my findings. In the meantime, we'll stick with those that are available. although I have to say from experience that I only ever consider using one type.
AE Hepolite has been manufacturing pistons on a massive scale for donkeys years, the Powermax piston being their range of race application items. The big bore piston seems OK, but the ring pack is nowhere near as good as the Omega set. I have also come across some real horror stories about them, and have not been particularly impressed by those that I have taken out of various engines where the engine supplier uses them as the norm. To cap it all, I was witness to one of the technical bods from AE state that this piston was not guaranteed (designed) for applications with CR's higher than 9.5 to t. A bit disconcerting really as their catalogue lists them as a direct replacement in an otherwise standard engine giving a CR of 10.3 to 1!! So be warned.
Alternatively we once again have the Omega range. And it is a range - 8 different types if you ignore special application flat tops. Seven or eleven cc dish, standard or low compression height, in their exemplary cast alloy, and worth every penny. They also do them in forgings, bullet proof, but only in a limited choice of styles.
Serious consideration should be made when choosing your pistons - a failure in this department can be VERY costly.