Roger King

Dave J. and Alex Wong have both got it right. There are two separate issues with fuel. Octane and valve seat protection. Octane is a measure of a fuels resistance to 'knock', variously known as detonation, pinking, etc, although people sometimes use these names to mean different things. Knock is a situation where the fuel no longer burns smoothly, but suddenly explodes violently at the flame front. This explosion can be enough to (seriously) damage the engine (pistons, head, etc). The higher the octane number, the more resistant the fuel is to knock. The two major factors that affect an engine's tendency to suffer from knock (leaving aside fundamentals like combustion chamber design) are compression ratio and ignition advance - the higher the ratio and the greater the timing figure, the more likely you are to have a problem. In practical terms, this means that you must run a fuel with a high enough octane to prevent this happening. At present, premium UL is 95 octane, whereas SUL, 4* and LRP are 97. It therefore follows that the last three are interchangeable from the point of view of knock. It is also true to say that if your engine is set up to run on 95 octane, there is no advantage (despite the stories people sometimes tell) in running a higher octane; equally, there is no disadvantage apart from in the wallet. What you must not do is run a 97 octane engine on 95 octane fuel. I do however, agree with the advice given by others here that it is a good idea to run the higher octane fuel on track simply because it gives some extra safety margin under arduous conditions. PLEASE NOTE THAT IF YOU HAVE A CATALYTIC CONVERTER ON YOUR CAR THIS WILL BE DAMAGED BY LEADED 4* OR LRP FUEL. IN THIS CASE YOU MUST RUN ONLY UNLEADED FUEL (OF WHICHEVER OCTANE IS SUITABLE). There is also the issue of valve seat wear. Older engine need lead to prevent valve seat recession; without the lead the engine will suffer long term damage to the exhaust valves and seats. This generally means Crossflows and some of the other engines used prior to the Vauxhall and K-series (these engines do not need lead, but won't be damaged by it unless there is also a catalytic converter fitted). LRP is generally reckoned to be a very poor substitute for proper leaded 4* and on a hard driven Caterham is likely merely to postpone the damage. The solution here is to fit proper hardened exhaust seats (usually possible), or, at a pinch, to run unleaded fuel with one of the aftermarket additives (beware, some are useless). A completely standard Vauxhall will probably be OK on premium (95 octane) unleaded, but check with Caterham first. SUL will do no harm, but once again, IF YOU HAVE A CATALYTIC CONVERTER, LEADED OR LRP ARE A DEFINITE NO NO. If you haven't got one then you can probably chuck in anything except diesel or paraffin! In response to Simon Ray; yes a customer did come over with an engine that I had built for him to run on 97 octane fuel and yes, he had put 95 octane in by mistake. The engine was a Crossflow with unleaded exhaust valve seats fitted and a compression ratio of around 11.2:1. Amazingly, it ran without any detonation problems whatsoever on the 95 octane fuel and with ignition timing at around 34 degrees full advance! I was amazed, but have since found that many Crossflows will run on the lower octane fuel without problem. Please note that THIS IS NO WAY IS A GUARANTEE THAT ANY PARTICULAR ENGINE WILL BE ABLE TO DO THIS UNLESS IT HAS BEEN CHECKED ON AN ENGINE DYNO OR ROLLING ROAD - sorry, but just covering myself there.

This shouldn't be a problem so long as when you come to reassemble, you are setting the cam timing by lining up the original marks. If, on the other hand, you are changing the cams, fitting vernier timing wheels, skimming the head by more than a minimal amount, etc, you will not be able to rely on the original marks to give accurate settings. In this case you will need to fit a timing protractor (usually onto the flywheel) and will need to remove the engine. There should be no need to remove the sump in order to remove the head, because the head bolts (often reuseable) are assembled from the top of the engine. One point of note - the bottom end of the engine will seize solid when the head bolts are removed due to distortion. This is not a problem because it will come free again when the bolts are refitted, but it is advisable not to force it to turn with the head removed.

Glenn, If you give the engine a good pasting, this sort of thing is more likely to happen, but the Vauxhall is not as prone to the problem as the Crossflow. If you have been indulging in hard cornering and braking this can make the problem worse too. I am assuming that the engine is wet sump. If this is the case, an oil level that is too high will not help. I strongly recommend that the breather is fed into a catch tank anyway. Apart from saving you from dropping oil onto your own tyres (don't laugh, I know someone who spun off on his own oil because of this), it will allow you to see how bad the problem is. A small amount of oil can look like a lot when spread on the chassis. You may then find that the problem is very minor, but if the oil level is correct and you really are throwing out a lot of oil at least you will know. If this proves to be the case, you will have to investigate further (possibly with a cylinder leakage test).

John E. When you obtained your emery board at Le mans, who was the camper, - you or him? Best Wishes, Roger

Brian, The K-series is proving surprisingly amenable to tuning - to the extent that it might even be a preferable starting point compared to a BDA. Throttle bodies and an accompanying replacement engine management system would certainly be my preferred first step, but be aware that many aftermarket systems cannot cope with running 'closed loop'. This is where the engine management communicates with the sensor in the exhaust system and alters the fuel/air ratio as necessary. The reason for doing this is that the catalytic converter requires very precise control of this ratio in order to function correctly. Correct functioning of this is checked in the MOT and can lead to failure. At the moment, amateur built cars are exempt from this test, but many testing stations seem unaware of this. It is also possible that this may change in the future. If you are certain that you will never need a catalytic converter for legal reasons in the future then don't worry about this, but personally I feel that it is good insurance to cover this point, especially bearing in mind that it is required for SVA. Any further tuning is likely to lead to piston failure, so the next step would be forged pistons for extra strength. After this, my preference is to convert to solid (non hydraulic) valve gear with suitable cams and gasflowing of the ports. The head works better than it has any right to do with such tiny valves, but there is no doubt that the VVC head with bigger valves and ports works even better. Certainly, if you want 200bhp this is the way to go. There are other items that are advisable to deal with at higher power levels, such as strengthened liners, valve springs etc.

Matt, I cannot guarantee that the following is exactly correct, but it is likely that the following has been done. Cam followers converted to solid operation and uprated cams used Head probably gasflowed Uprated big end bolts Not sure if the pistons are uprated or standard (I would use a purpose made piston from choice) Carburettor mods - choke sizes, jetting etc Possible remapped ignition ECU Uprated valve springs are possible, but in many cases were left standard In the absence of information about the compression ratio it would be wise to run on superunleaded fuel unless you can get confirmation that standard unleaded is OK. To say the least it is highly unlikely that the valve seat inserts have been modified to need leaded fuel. Try Swindon on 01793 531321. If that doesn't work (it's a while since I rang them), give me a ring on 01992 421111 and I may be able to find a more recent number Edited by - roger king on 24 Aug 2000 01:36:55

This is a common problem with 45dcoe (but rarely 40dcoe) carbs and it by no means affects only Zetecs. The usual effect is that you have a flat spot on very light throttle which can make the car unpleasant to live with. Basically, the engine is being under-fuelled at this point. There are two possible cures:- 1)Fit special butterflies with a slot machined in them near the progression holes - these are no longer available, but you could machine your own. 2)Machine an extra progression hole into each barrel. This does really need to be done on a jig with the carbs off the car. It is generally effective at reducing the problem, but you should also make sure that your jetting (slow run jets) is correct for the application too.

This is outside my area of expertise, but I have seen similar problems before and they have usually been caused by a faulty earth under the dashboard. I believe that there is a point where the loom earths to the chassis under the scuttle on the passenger side. Sometimes this becomes unreliable due to loose connection or even the chassis powder coat getting in the way. Worth checking anyway.

As a general rule, a 4 - 1 system will give a higher maximum power output than a 4 - 2 - 1 system, but the power band will be narrower. To illustrate this, race cars often have the former type, whereas rally cars have the latter. It should be understood that exhaust design is something of a black art, so the above is a generalisation only. Being such a light car, the Caterham can cope with a 4 - 1 system quite easily. If you are wanting to use one of Cateham's systems, my advice would be to stick with the rear exit system up to around Supersprint specification and use the 4 -1 system for more highly tuned units.

I can make no claim to being an expert on lubricants (not quite sure that brings the right mental picture to mind!), but as an engine builder I can tell you that Crudders is about right - the oil goes black as it absorbs the products of combustion (and also microscopic metallic particles) in suspension. This is meant to happen, but you get to a point where it needs changing. As you might logically expect, it is quite noticeable that this blackening occurs faster in an engine with piston rings and bore that are below par. If you build an older type engine to modern standards of bore finish, bearing materials, piston ring design, etc, then I can only say that I would always recommend a synthetic oil over a mineral oil except for the first 800 miles of running in. If there ever was any truth in the story about older seals being affected by synthetics, this will be irrelevant if new ones are fitted. It is very noticeable how much cleaner an engine stays internally when synthetic has been used (especially in very hot areas like the underside of the piston crown). Personally, I like Mobil 1, but I'm sure that others will be loyal to other brands. Don't forget that just because oil seems thin when it is cold (like the 0w/40 Mobil 1), it doesn't necessarily follow that it will be like water when it is hot. The first number in the designation (0w) refers to the oil's viscosity when cold, whereas the second number in the designation refers to it's viscosity when hot, (40). Viscosity when hot will be the same as any other oil that has 40 as it's second designation; therefore if you compare it with a 20w/40 oil, this will be much thicker at ambient temperature, but the same viscosity when it is hot. Does that make any sense? Talking of running older engines; my fifty year old sidevalve lawnmower is running on Mobil 1 (mainly as a satirical gesture), and it hasn't complained yet.

Pierre, I'm sorry, but this is a mod that we haven't tried, so I can't give you any definite answer to your question. I suspect, if your 1600K is standard that it would make only a small difference (if anyone else has tried this they will know if I am wrong or right)! If your engine has been modified then it will posssibly make a reasonable difference. If, on the other hand, your engine is heavily modified, a proper 4into1 or 4into2into1 system would be essential.For example, we have recently done a 195bhp upgrade for a customer on a 1600K, but this figure would not have been possible without a competition type system. Roger King

Alex, It's easy with NGK. The higher the number the colder the plug and as a general rule the more highly tuned an engine is, the colder the plug you should run. Note though, that this rule will only apply for any particular engine type, i.e. just because a heavily modified Vauxhall might need an 8, this doesn't mean that an equivalent Crossflow will also need an 8 (in fact, with it's less efficient combustion chamber, a Crossflow may need to go even colder on plug grade). The other letters in the plug type refer to all sorts of factors:- thread diameter and length, electrode design, hexagon size, resistor type or not, etc, etc. Throughout all this, the heat number remains consistent so that an 8 grade is the same heat range even if every other factor in the plug designation is different. At a guess, a good general plug for an engine of your type would be BCR8ES, but, IT IS IMPORTANT TO REALISE THAT THIS MAY BE WRONG AND THE ONLY PERSON WHO CAN DEFINITELY GIVE THIS INFORMATION IS THE ENGINE BUILDER. Certainly, a plug that is too hot might melt, leading to poor combustion and possible detonation problems

Depends on engine spec whether it is worth going for the side exit system. Up to about Supersprint spec the side exit system really makes very little difference to the outright power figs on the rolling road, although it can make the engine a bit freer revving. Beyond Supersprint power figs the side exit system becomes almost essential if the engine is to realise it's full potential. Two points:- The Caterham side exit system has unequal length primaries, which is not a good idea in theory. In practice, it is a good general purpose system that will suit a wide of engine specs; it is also very well made. For ultimate power you would need an equal length system made to suit your own individual engine spec. The one problem with the Caterham system lies in the fact that the silencer cannot be repacked when it becomes noisy. Techcraft make an excellent range of silencers that can be dismantled to repack as necessary. Maybe the Caterham primaries and collector coupled with a Techcraft silencer would be the way to go.

Alex, Difficult to tell from the pic, but on the face of it, it doesn't seem like classic detonation. Photos of the crown and the piston skirts (both sides of piston) would help. I am a little suspicious of localised overheating or lubrication breakdown. Detonation tends to appear as a grey, grainy surface on the edge of the crown and running down the side of the piston. It often busts the rings. Also, what state were the spark plugs in? rkingeng@aol.com

We don't sell oil so I have no axe to grind on this one. We have always found that Mobil 1 is an excellent product and tend to recommend it for most applications. I agree that the 0w/40 is best for a Vauxhall, but would point out that an oil cooler (with thermostat) is a very sensible idea, especially on track days. If the cooler is not needed on a particluar day the thermostat will simply keep it out of the circuit. I have experience of a car that came in to the pits with rattling hydraulic tappets when the oil got (very) hot. The next time out a cooler had been fitted and even though the ambient temperature was hotter the problem did not re-occur.

Pierre, Re your question of 29/07/00 about the head bolts. The K-series has a rather strange construction in that the head bolts go right from the top of the engine through to the bottom, so they are therefore effectively the main cap bolts as well! The good news is that they do not need to be removed to do the Supersport conversion. You only need to undo the top half of the cam carrier (this is the second layer down - the top layer being the cam cover). As a first step to tuning, the Supersport conversion is very good value and retains good driveability. If you want more power you will need to spend considerably more money. The emissions question is very important and if you do opt for more tuning you MUST make sure that your new engine management system is compatible with the lambda sensor in the exhaust. rkingeng@aol.com

This year we have experienced a 100% failure rate with Facet red and silver top pumps that we have sold! Needless to say, we no longer feel able to supply them. The best alternative I've found for highly tuned engines is made by Holley and could be described as overkill, being intended for American V8s. It is a bit more expensive than a Facet, but not too much. For less powerful units it might be worth trying the Facet solid state pumps (but use the competition version). Purely by chance, I found out today that Facet are going to modify the internals of the red and silver top pumps - I wonder why? Unfortunately, it seems this won't be available until next year.

Firstly the induction noise. This is perfectly normal on any engine with a pair of DCOE carbs. You may have had the same sort of set-up on your previous twincam cars (assuming they weren't on Strombergs), but the carbs were probably under the bonnet rather than poking out. This makes a considerable difference to the perceived noise level. Popping from the exhaust on the overrun is quite common and is usually worse with the 4 into 1 side exit system due to small air leaks at the joint. As a general rule, the better the engine is set up, the less this will happen. Mechanically, the Crossflow is quite noisy. Although the Twincam is of similar vintage, it has much more sophisticated valve gear which helps; throw in the lack of hydraulic cam followers, relatively rigid engine mounts and several other factors and the extra noise becomes inevitable. Bizarrely, the rocker cover often acts as a resonating chamber and changing to a different type can sometimes make the problem better/worse. Exhaust noise is largely down to the silencer type. They do deteriorate over time and fitting a replacement (Techcraft make an excellent range) can transform matters. Roger King rkingeng@aol.com

There have been at least two flywheels fitted as standard to the HPC - one heavy, one very heavy. If yours is of the type where the clutch cover sits on a rim that is raised above the face that the clutch plate sits, you have the latter. Two possible solutions - 1) fit a purpose made steel flywheel and suitable clutch 2) fit an even lighter race flywheel and clutch (not recommended for road use unless you are very enthusiastic)! You can also lighten the original, but there is not that much difference to be made safely.

Assuming that by 'external tank', you mean the one that Caterham would normally use with a Crossflow/BDR, the best procedure is as follows. 1) Fill the tank to be level with the top baffle. 2) Remove the spark plugs so that the engine will crank as fast as possible. 3) Disconnect the ignition system so that it does not try to produce sparks (disconnecting the crank sensor will do if the power is not left on too long). 4)Crank the engine until some pressure shows on the gauge (you will hear the engine slowing down as this happens). 5) Refit plugs, connect ignition, fire engine and run for a couple of minutes - ensure that the oil pressure is good. 6) Stop engine and top up tank to 1" below the top baffle immediately (If you leave the engine to stand, the oil often drains down into the engine via the oil pump; this will then show a false level in the tank). Notes. This procedure may not be a good idea if you have brand new cams which need bedding in. Slow cranking with poor lubrication can damage the lobes. Don't forget to get all the old oil out of your filter housing, oil cooler, pipes etc, before filling with new oil. If you use Safety Kleen or similar fluid to clean the system out, the new oil will initially become frothy until the residue has evaporated away.

Hi Tony, Unfortunately, despite the kind recommendations, I don't know either, because we always put our own number on an engine! However, if you would like to give me a ring (new number 01992 421111) I might be able to put you in touch with customers who have early cars and therefore might know.

109 degrees is OK with most syntetic oils (most manufacturers seem to say they're alright to 140 degrees), BUT, as one of the above replies mentions, the oil is also working as a coolant for the engine. My advice in an ideal world is to maintain an oil temp of around 80 - 90 degrees. This needs an oil cooler AND an oil thermostat (oil that is too cold is also not a good idea). As a word of warning, we once ran a steel Crossflow without an oil cooler on the track (synthetic oil but the hottest day of the year), and it threw a rod after suffering lubrication failure.

Yes, the rear of the crank is machined out on a jig to take a Ford/Vauxhall spigot bearing.

As a general rule, any Caterham (1600 Sprint to 230bhp Vauxhall) running on a pair of Webers will return around 20mpg in average road use. In the unlikely event that an enthusiastic driver has a go, this might get a bit worse...... This is largely due to the lack of any vacuum advance mechanism to provide needed extra advance under part throttle conditions (which on the road happens most of the time even with looney drivers). 3D mapped ignition can usually improve this by between 15% - 25%, because it adjusts the timing to increase advance at light throttle (if correctly mapped).