Roger King

I'm not an expert on the different suffixes but quite often they indicate a version made for a specific purpose. Having been out of the business for over 15 years I may be out of date, but so far as I know the 151 is still the current "general purpose" version that is expected to be re-jetted to suit whatever purpose the customer has. The really big difference appeared in about 1980 (only an approximation). Before this DCOEs had plain throttle spindle bearings that wore out rapidly, circular brass floats that often sprang a leak, and no idle bypass screws for the butterflies. Later ones are vastly better, having ball races for the spindle bearing, black plastic rigid foam floats that can't puncture and idle bypass screws. I suspect they were forced into this by the fact that Dellortos had all of those features. The idle bypass screws are the easiest way to spot later carburettors; they are positioned, one per barrel, on the outside of the body near to the butterflies. When new they had white plastic caps on them, covering the adjuster screw and locknut. Unless you are after historical accuracy, I can see no sensible reason to use the earlier type.

It's impossible to answer this with any certainty, but it sounds like a fuel supply problem; the rise in revs at idle may mean that your mixture screws are set too rich and the fuel supply problem is actually correcting this. Causes could be - faulty pump or wiring, fuel line blockage, non venting filler cap, stuck float or needle valve, dirty filter in the carburettor, foreign matter in the fuel tank - and I'm sure there are many others. Years ago we had a 7 race car that would test out perfectly each time on the rolling road or even on the real road, but at every race it would misfire after a couple of laps. It would always run perfectly a few minutes later. We tried everything we could think of and eventually changed the tank which solved it. It turned out to be some rubber-like debris that was larger than the bore of the fuel pick up, but would every now and then get sucked up and almost completely block it; once the fuel pump was turned off it would drop back to the bottom of the tank and the problem went away.

That's not a huge pressure, but it would be better down between 2psi and 3psi. The first thing is to get the pressure checked so that you know for certain what you have, and ideally fit a regulator if it's too high. However you are not into the ridiculously high zone if the stated pressure is correct, so it may not be causing any issues.

Fuel pressure should be around 2psi which doesn't sound a lot, but all it needs to do is dribble fuel in at the rate it is being consumed. Excess pressure is a more likely problem if you have an electric pump. If you have a mechanical pump, check that the diaphragm isn't split as this can cause fuel to leak into the oil: an inexplicably high oil level is sometimes also a clue that this might be happening.

First place to start is checking your float levels, the state of the needle valves and your fuel pressure.

I always remember my old boss, Bill Blydenstein, stating that 0-60mph times were irrelevant, and the correct way to do things was to measure 30-70mph both through the gears and then in top gear only. This would then allow you to judge not only outright acceleration without traction being a factor (in most cases!), but also the engine's flexibility. And I agree with him.

They always leak! I had a bit of a shock after leaving Dealer Team Vauxhall and going back to work on Ford's engines. We only ever fitted the sump gaskets to the Vauxhall lump in the Chevette with a little smear of green Hermetite on the block face - and that was for the sole purpose of ensuring that if the lads had to drop the sump during an event, the gasket would stay in place and not need changing. They never leaked. Ford sumps on the other hand? Let's just say that a sparing application of RTV is de rigueur.

Your figures are actually quite good, especially at warm idle. A high pressure pump merely involves changing the relief valve spring so there is no point in buying a whole new pump. Of course you should take the original pump apart and check that the internals are still sound (this is very easy), but if they are, a new spring is a lot cheaper than a new pump. A high capacity/high pressure pump is an improvement, but may well be an improvement you don't need depending on what you have done to your engine. The reason you would need a high capacity pump is if the engine demands more oil flow than standard in order to maintain pressure - examples might include the oil gallery on the pump side being drilled to spray oil onto the dizzy and oil pump gears, the engine being built with "loose" bearing clearances or even having a feed to lubricate a turbo. If your oil pump has excess capacity, the relief valve will simply dump the surplus into the sump, so you could argue that it's simply nice to have a bit in reserve. It should do no harm on a standard engine, but will likely provide no benefit either.

28,000 miles is about the point that a road driven Supersprint typically starts to give up the ghost. You have pistons designed for a 55 bhp engine being used with a much higher than standard compression ratio and producing around 120bhp; not only that, it will be revving much higher than normal. Assuming that nothing else is found that is wrong, it is usually the piston rings and/or pistons that give up. The rings are much more highly stressed than they were designed to be and lose their tension, failing to seal, and the pistons sometimes crack between the rings. Either way, the engine gets smokey. The only answer if this is the problem is a new set of pistons and rings. If you can stretch to it, a rebore and a set of 83.5mm forged pistons are far preferable, giving longer life and more power. Before anyone says Supersprints last much longer than that - yes, I have seen a healthy Supersprint with 80,000 miles on the clock, but I have also seen the above failure at less than 2000 miles. 25,000 miles is merely a typical figure and given the average annual mileage that a Caterham does means that the car would have been well out of warranty by that point.

Now I think about it, there were some instances, particularly with the yellow plastic type dipstick, where the stick would fail to go through to the oil via the hole in the sump baffle and would instead end up bending and sliding along the top of the baffle. This would give a zero reading even with a full sump. Before you dismantle anything, I'd drain the sump and then (if the oil is reasonably new), put the correct amount back in. Then see what happens, both to the leak and the dipstick reading.

I'm largely reiterating what others have said here. To fix the crank seal you would have to separate the flywheel from the engine so this would mean engine (preferably) or gearbox out. The sump would also have to come off, along with the rear seal carrier. However, as others have said, if this is a "static" leak (i.e. it occurs when the engine is not running) the oil level should not be high enough to leak from the rear seal. The same would also apply to the sump gasket. Are you certain that you have the correct oil level? If for some reason it is too high it is just possible that reducing it will solve the problem. If not, a pin hole in the sump might be the problem. Thoroughly degrease the bottom of the engine and put a piece of cardboard under it to see where the drip is occurring. You can also rub talcum powder on the sump to help with this, but don't leave it overnight; check it soon after starting the test. If you do decide to go down the route of seal replacement, then yes, you would need to remove the sump and rear seal carrier and replace gaskets and seals. Do fit the sump gaskets with silicone sealant; they are notorious for leaking if fitted dry.

No, on a straight four cylinder engine, the crank and flywheel assembly should be in balance as an assembly, but it is only necessary to have all pistons/rod assemblies balanced so that they are the same as each other. By this I mean that all pistons should weigh the same as each other, and all rods should weigh the same as each other (and each rod should have similar mass distribution end to end, or at least as near as is practical. What I'm trying to say here is that you don't want rods of equal weight, but with some having a lot more mass at the little end and some having more at the big end). If you think about it, the crank and flywheel assembly will be in balance without the pistons/rods attached, but when you fit them, two piston/rod assemblies go up at the same time as the other two are going down, thus canceling each other out; therefore their absolute weight is not important. In any case it's impossible to get any engine in perfect balance in all respects, and some, such as a V6 are much more involved. In all likelihood, the crank will have been drilled by Ford during manufacture because, contrary to popular opinion, they do balance them at the factory, although the alignment marks suggest the assembly may have been done again at some point.

It's an impossible question to answer because it depends on how well it was done originally. Personally, I always balanced the assembly so I could be certain, but some needed more work than others. If you do decide to balance, make sure that the crank is done first and then add the flywheel. That way in theory at least, you can swap the flywheel for another balanced one and things will still remain correct. I have encountered some balancers who do the whole assembly in one go, but this means you can't change anything without starting again.

If that tank is as good as it appears to be it's incredible value for money. I assumed it was plastic until I read the blurb. As always, the proof of the pudding is in the eating.

Whoa................have you checked the ignition timing? Ideally on a Supersprint you should have around 12 degrees at idle and 35 degrees at full advance (from around 4500rpm). The usual cure for light throttle spitting on a Supersprint is to change the 45F9 slow run jets to 50F9. You will appreciate all the usual caveats about my not knowing your individual engine, but this cures the problem 95% of the time assuming that you don't have other issues.

That hose shouldn't be there. In a "normal" car it would go from the inlet manifold to the heater, and then back to the water pump. In other words it's where the heater gets its heat from! Without a heater, it is completely pointless and is in fact a potential source of airlocks in the cooling system. Not only that, being a Lotus (sort of), you are carrying unnecessary weight around, which, whilst not an actual crime, is at the very least a sin worthy of a visit to confession. On the other hand, the good news if you are installing a sealed cooling system is that you already have the return pipe on the water pump to plumb in from the bottom of the header tank. You will need to plug the inlet manifold though; you need a 3/8" bspt plug for that.

To answer three questions. You need the outlet at the very top so that any air bubbles will go straight up the outlet and into the header tank; this stops the system from building up an air lock somewhere and causing localised overheating. The way the system is plumbed means that the water pump is continuously trying to pull water down from the bottom of the header tank and the top hose to the tank is continuously returning air to the top of the header tank. You also don't need a rad cap on the casting because a) you use the cap on the header tank to fill the system and b) they're notoriously unreliable and often the source of air leaks. I would always fit the bottom hose from the header tank into the bottom hose but in theory it could go into the heater hose. I've not tried doing it that way, but the most obvious problem would be that if the heater is a water valve type, turning the heater off might disrupt the flow in the system (but it might not because in theory there would still be a circuit in operation via the header tank). You'll have to try and see if it works. The reason for having a sealed system is to improve cooling and reliability. Before sealed systems were fitted to Caterhams it was very common to see the following - a driver would spend a morning at a track day, before which they had checked their coolant level. During the session, the coolant became hot, expanded and was partially expelled via the relief valve in the filler cap. Then they'd stop for lunch during which the coolant level would be checked and found to be OK. But by the time the afternoon started, the system had cooled considerably, the coolant had contracted, and the filler cap had sucked in air to replace it (in theory it would suck the water back in from the catch tank - if fitted - but this almost always fails to happen) so they go back on track with air trapped in the system and within half an hour suffer a head gasket failure. I can honestly say that when we started fitted header tank systems we at a stroke eliminated over 95% of such failures at track days. With a header tank system, expansion of coolant takes place into the partially filled header tank with any excess pressure being relieved through the filler cap as air. Then, when the system cools down, it sucks air back in again, but crucially, no coolant has left the system and the air stays above the coolant. There's a reason that modern cars of all types run such a system and it's to do with reliability and reduction of warranty claims. Incidentally, if a header tank system loses water, it is nearly always because the pressure cap has failed; as this is the cheapest thing to check I advise to always carry a spare.

Wow, that's one of my diagrams that I drew up some 25 years ago; good job someone still has a copy! The only things I would add are that if you have a heater you will already have the return hose from the matrix attached to the small pipe on the water pump; in this case you need to put what used to be called a submarine into the bottom hose (this is basically just a T-piece) and feed the lower hose from the header tank to that instead. Alternatively, if you do not have a heater there is a good chance that you will simply have a blanking plug in the water pump; in this case you need to remove the plug and fit an inlet pipe (back in pre-history the Ford part number was 6148087, but I have no idea if this is still current or even if the part is available now). In addition, it is essential to fit a thermostat housing with a vertical orientated small outlet. I don't know if the Fiesta one I used to use is available now (was Ford part number 6814635), but something might suit as an alternative. If there isn't one already, drill a small hole of around 1.5mm in the thermostat to allow any air bubbles to pass through it and up the thermostat housing. Finally, the header tank type isn't critical, so long as it has a screw on pressure cap, a large lower outlet and a small upper inlet. If it fits it should be fine, but mount it as high as possible.

Aluminium is fine for the block as well, but just keep the interference fit to a minimum. Steel would be just as good though. As per my previous post it would be a good idea to give them a top hat section with a small "brim" of just a few thou. to stop the plugs falling inside.

I would use one of the Loctite retainers, perhaps 641 if that is still current. This will both seal and retain the plug (if you are using a turned plug rather than a thin welch plug type item). I'd recommend the plug is aluminium, particularly for the head, so that you don't encounter any differential expansion problems. You need to thoroughly degrease all surfaces and it would be a good idea to roughen the joint surfaces up a little to allow the retainer to grip more efficiently. In reality, you should be fine with a plain aluminium plug and an interference fit, but belt and braces never hurt anyone.

I've never used anything like that so I can't really comment other than to say that the breather hole in the block is not very deep so these plugs may be too long and that I would be very keen to make sure that nothing could vibrate loose and let bits drop into the block or head. Another way might be to turn up some plugs with a top hat shape that are a close slip fit into their locations. The "brim" section would stop them falling into the engine and they could be secured with one of the stronger Loctite retainers; I've not done this ever so be very sure that all is thoroughly degreased and secure.

Firstly, I need to say that I came out of the competition engine world in 2003, so I may be a little out of touch. However, it used to be possible to buy blanking plugs for both the block and head. The plug in the block is exactly the same as would be used in a Crossflow block. I'm not sure about the size of the plug needed for the head simply because I have never built a BD(insert your preferred suffix here) that wasn't blanked off from new in the factory, but I wouldn't be surprised if it's the same as the block. You can see the plug in the head here and it should be quite simple to get one turned up in aluminium so long as you can measure the diameter of the hole. Failing that, http://www.burtonpower.com will probably be able to help here in the UK. I would strongly recommend an interference fit of around .001" with a lead in about .002" smaller and the use of a Loctite retainer; centre punching the block and head around the plug will also help to keep it secure.

Is the engine dry sump? If it is, the breather above the fuel pump is redundant and should be blanked. If you have a wet sump engine, opinions vary! Personally, I feel that the breather hose at the front of the block is perfectly sufficient, but some will argue the point. I have to say that I have built very few wet sump BDAs (or whichever suffix your particular variant is - I suspect BDR). The works rally engines were all dry sump (obviously) and were also aluminium blocked, so several things, including breathing and the oil system were laid out in a non-standard way. When I started to build BDR kits from Cosworth I had to get used to quite a lot of differences. The most surprising was that Cosworth supplied what appeared to be unsuitable hose for the front oil drain. This rapidly hardens with heat and oil exposure and is almost guaranteed to leak after a while. Replace both this and the front breather with softer, oil compatible hoses. Don't dismiss the front camshaft oil seals, particularly since they are so close to the drain/breather hose. I posted earlier in this thread about them; in my experience, adding the oil drain holes makes a huge difference. Most will leak without the drain holes, but occasionally you might get lucky.

Compression ratio is dependent on many things - cylinder capacity, combustion chamber design, camshaft profile, 2 or 4 valves per cylinder, induction system, exhaust system, carburettors or fuel injection, design of the cooling system, type of ignition system, etc, etc. Fifty years ago, it was generally reckoned that 9:1 was about the limit for road cars on 98ron fuel, yet we now see plenty of engines running over 11:1. Here are a few reasons - 4 valve combustion chambers generally have a shorter flame travel, better atomisation and therefore a quicker burn time, fuel injection (or more crudely, one carburettor barrel per cylinder) gives much better control over fuel/air ratio in individual cylinders than a single carburettor which reduces the likelihood of detonation, better designed water passages in the engine reduce the instances of hot spots in the combustion chamber, more powerful ignition systems give a better burn, piston ring design is much more effective which reduces the amount of oil getting into the combustion chamber; oil can lower the effective octane rating of the fuel. I could go on. Suffice to say that for a road going Crossflow with twin 40s or 45s, I'd stick to just under 11:1 as a maximum if using 98ron fuel, although for full race use you can approach 12:1 if you know what you're doing. This is just a generalisation and can't necessarily be applied to any individual engine specification. By the way, if an engine builder isn't happy to machine pistons to alter the compression ratio, he/she isn't an engine builder!

My best guess is that this is an emissions strategy designed to reduce excess HC emissions which are always, and inevitably, a problem with transient enrichment - but I'm more than willing to be schooled about my errors by those better informed.