Roger King

That's the seal for the flupher valve that connects to the grauble pin (left hand only). Seriously, I can't think, but a photo might help.

If your head is suitable for unleaded as stated in the heading for this topic it will already have hardened seats fitted.

That's an unusual fitting and looks as if it's just a push on and jubilee clip type of fitting, although it will need a larger bore hose for the breather than is normal (unlikely to cause a problem though). In the top right hand of the photo is the type of fitting that is more usual. For this you would need to machine the back end of the rocker cover and tap a 3/8"BSP thread into it. Then a hose can be connected with a jubilee clip again; make sure you use oil hose and not water hose.

If the head is suitable for unleaded you don't need to add a lead substitute. It's as simple as that. I can't comment on the octane rating because I don't know the spec of your engine. The higher ethanol fuels won't affect the valve seats, but may have repercussions for your hoses.

It's not generally common to fit a vac advance to DCOEs because you get such a strong pulsing from each inlet tract that it can send the dizzy into a spasm. However, you can in theory connect all four inlet tracts together so the dizzy then sees a smoothed out signal. In practice I haven't found it to work too well but some playing about, maybe fitting a restrictor in the system to damp things down further might be worth trying. Bear in mind that this would be your experiment and your responsibility! The principle, however, is very sound. 3D mapped systems which generally work off throttle position rather than inlet manifold depression aim to have the same result and are most definitely worthwhile.

Loose dizzy and blocked fuel tank breather are possibilities too, but please check the fuel filter and the aux vents first. If the aux vents have moved this will block fuel from one or more of the main jets and can cause symptoms exactly as you describe. I was asking about how much throttle you were giving it to try and determine if your problem was on the main jets or the slow run jets. From your original post I get the impression that you can rev to 4000rpm + if the engine is under no load. Is this correct? It is not usual to fit a vac advance with dcoe carburettors. Having said that, they seem to have gone about it the correct way if there are interconnected tubes from each inlet tract. The vac advance should help with part throttle response and fuel economy if set up correctly in much the same way that a 3D ignition system will. Just to be sure, pull each hose from the inlet manifold, plug the resulting hole in each inlet tract and try the engine again (you do not need to plug the dizzy or the tube leading to it since it does nothing if it sees atmospheric pressure). If you have excess hose you could cut four small lengths of that and wind a screw into each one to plug it; make sure nothing can get sucked into the engine.

Is the engine a Caterham supplied Supersprint? Does this problem occur exactly the same whether you are on large or small throttle openings? Did you drive the car with the new carburettors and parts before the rolling road? If so was it reasonable to drive then and did the problems only occur after the rolling road? Does your invoice show you what was changed and what your current choke and jet settings are? Do you know what advance curve is in the new dizzy? You should check the following - Bypass the new filter and see if that improves fuel delivery to the carburettors (you're looking for more than a dribble, but not a fire hose squirting across the room). Check float levels. Check that the aux vents are in their correct positions; if you look down the barrels the aux vents are the circular aluminium tubes that are held in the centre of the barrels by two arms - the aux vents should all be in the same position as each other (just to be clear, the barrels adjacent to each other on the same carburettor are actually mirror images of each other, so you need to allow for this when I say "same position"). Photos would be useful.

Wot he sed (about a mechanical sensor), but the figs are actually not too bad. One bar at idle when hot after a run is OK; a high pressure pump will make no difference at all at tickover because they simply have a stronger spring in the relief valve which has no effect until the pressure reaches much higher levels. To increase idle oil pressure you need a high pressure/high capacity pump. Ideally, I'd like to see 3.5 to 4bar at high revs - what are you getting at around 5000rpm? If you're anywhere near those figures there is probably nothing wrong, although I can't explain about the light taking so long to go off. You probably have a standard road type light switch which will would normally be set at around .4bar. Unfortunately these lights are really only of use to tell you that your engine is already b*ggered. A competition light switch will be set to nearer 2 bar. This will give you advance warning that something is going wrong but you have to put up with it coming on all the time at low revs.

First check is to disconnect the cable. If it now returns to the correct idle speed when hot the problem is in the cable or pedal linkage. If it's the same you need to investigate further, but the cable is the usual suspect.

I don't advise a single chain tensioner pad on a duplex chain. It can cause the chain to be twisted when running. Use a duplex tensioner (which I hope Burtons can still supply). It's only the pad that is different, the actual spring mechanism is the same.

Thanks guys it seems that this is going to be quite easy as I'd hoped, but not really expected. Yes, it's just the coil. This is only for the test stand which has no lights, wipers, etc. (actually not very much etc. seeing as it's a Jeep - oh yes, they have a horn too).

A friend of mine rebuilds the occasional Jeep engine (WW2 era, so real Jeeps). He likes to run them up on a test stand before sending them out; this is not a dynamometer, just a flying bedstead to check for leaks, rattles, misfires, etc. The Jeep of this era is negative earth, but 6 volts and with contact breakers to trigger the coil. The problem is that a 6 volt battery has to be kept fully charged all of the time and even then struggles to turn a relatively tight new engine. It is very important that the customer's Jeeps retain the 6 volt system because almost to a man or woman the owners are much more fastidious about originality than most classic owners. So, he has tried using a 12 volt battery to crank a fresh engine in order to raise oil pressure initially. This works very well, even if in theory he's overdriving the 6 volt starter; and as he says, on the test stand the starter gets very little use so he's prepared to do this and see how long it lasts (it belongs to the test stand and not the vehicle). Ultimately he could have the starter converted to 12 volts to but that would leave a 6 volt ignition system being fed 12 volts and presumably over loaded. So after all that waffle, my question is this. Is it possible to use the 12 volt battery, but fit a resistor in the feed to the ignition to drop the voltage? All gauges, etc, on the test bed are mechanical so it is only the ignition that needs this feed. I have done a very similar thing on my grandchildren's train set where each LED light is fed 12 volts, but via an approximately 1000 ohm resistor. That works, will this? If anyone can give an informed answer - is it possible? what value and current capacity resistor (the ignition will not be a heavy load, unlike the starter) would be needed? where to obtain such a thing? Is this an insane idea?

It might be the idle jets being a little too small - this is extremely common on a Supersprint engine with 40DCOEs where a change from 45F9 jets to 50F9s often makes a huge difference - but with 45DCOEs it is more usually a problem with the progression holes. These are located under the round brass caps near to the mixture screws (two per carb.) and the problem is usually that there aren't enough of them. The most common case is that you need one more small hole just a little nearer to the top edge of the butterfly when it is in its closed position. This gets the fuel flowing just a tiny bit sooner when you open the throttle a minute amount. Effectively this is filling in a dead spot in the fueling where the fuel/air ratio is far too weak. Two caveats: I can't be certain that this is the problem because I haven't seen the vehicle (although it is usually the first thing I investigate with 45DCOEs), and unless you really know what you are doing this modification needs to be done by someone who does.

You can always use steel rods, but if you're sticking to 7000rpm the standard item is generally fine so long as they are checked for cracking and they are then balanced as a set. If you polish the flanks of the rods in addition to the above you can normally extend to 7200rpm. See photo. Please note that the above is given as generalised advice only and may not apply to a specific engine specification.

The link below shows where you can get them. 83.5mm will give 1700ccm and is just very slightly larger than the bore for the +.090" pistons that Caterham used which gave about 1690ccm. https://www.burtonpower.com/catalogsearch/result/?q=accralite+crossflow+piston Note that the standard +.090" pistons that Caterham used are nowhere near as good as the forgings from Accralite; these are much stronger, significantly lighter, and despite much lower friction from the rings they actually seal much better, though they do require a plateau honed bore finish. Believe it or not, just changing to the Accralites will typically add around 10bhp to the top end of the power curve simply due to lower friction (you can actually feel the difference when you install them into the bores). You may need to machine them to get the correct compression ratio and while most valves will suit the valve pockets, you need to check that you have adequate clearance.

Either a 234 or 244 will work well on the road, but only if the rest of the engine is uprated to suit - forged pistons, decent big-end bolts, doweled flywheel, tufftrided crankshaft, properly flowed head, decent dizzy or 3D map (preferable), better valve material (and possibly bigger too), higher compression ratio, uprated rocker shaft, better valve springs, rejetted carbs with different chokes, etc, etc. The 234 is slightly better at low revs and the 244 gives a bit more top end as you would expect, but both are fine on the road. 3D mapping or injection would be the icing on the cake. Even a 264 can be road drivable when set up properly; my test for road use was "can I sensibly drive it in a multi-story car park?" which may seem a bit odd, but light throttle and low revs are much harder to set up for than outright power. By the way, a 264 will need a lot more engine changes than listed above. The Caterham Supersprint uses a 234, but they came nowhere near getting the best from it. I used to see around 120bhp from the later ones, but we had at least one super-special engine that achieved just over 150bhp on the same cam.

The 711M is an excellent block and can be tuned right up to full race spec, but the AX is even better. You cannot take a 711M to 1800ccm, but as a general rule the AX will bore out that far; it is ESSENTIAL to check bore wall thickness before you try though because you will occasionally find a "rogue". The AX is also slightly heavier and stiffer, but it is significantly smoother running as a result. You may well find that it liberates a couple of extra horsepower for the same reason. Finally, it appears to be cast from a different material because it suffers less bore wear than the 711M.

The EE appeared on many blocks and doesn't indicate a specific builder. Is it an AX or a 711M? It should be the former if the date is correct.

No problems with synthetic. We used to run all of our X/Flows on Mobil 1 from the late 1980s. I confess that I can't remember the grade, but 5W/50 comes to mind. There are a lot of myths about synthetics including oil leaks and failure to run-in, but most of them are either groundless or only apply in a very few specific cases. However, you'd be advised to make sure your engine is flushed first by running with some fresh ordinary oil to try and remove any sludge. You can get flushing oils, but I've never used any so can't comment on them; they may be fine if used as per instructions. It's more a question of the engine's previous history. Unless your engine is extremely old (several decades), it is highly unlikely to have seals made of a material that would be affected by synthetics and it is presumably fully run-in by now. So it comes down to the question of "is it worth the cost?" and I would say that this depends on the condition of your engine. If it is heavily worn, I'd say no, but if in good condition yes. I am aware that Mobil now do versions claiming to be suited to higher mileage engines but I've never had any experience of them. What I can say is that engines run on synthetic from new are always much cleaner inside, with less sludge and much less charring on the underside of the pistons (which is just about the hottest part of an engine).

It is generally the case that aluminium radiators must not be stressed in any way so they must not be rigidly or even semi-rigidly attached to anything that can flex.

Quite true, but it's not necessary to use more than a few psi to find an air leak. And it gives a visual indication rather than having to wait for the pressure to change - plus it can be done with a bicycle pump if you don't have a compressor. This is how we used to test all radiators, intercoolers, oil coolers, etc.

This is the reason I'm not keen on braided hoses. Despite the attractive appearance you simply don't know what is happening under the surface.

"Use short pieces of hose and suitable plugs for the hoses such as plastic plumbing blanking plugs, with hose clips to keep them in place. Through one plug insert a rubber Schraeder tyre valve stem. Fill the radiator as full as possible with water, then increase the pressure up to 1 bar with a tyre pump on the Schraeder valve. Confirm the pressure stays for at least an hour without any leaks." Agreed, except that is easier and quicker to pump air only into the radiator and then immerse it in water, obviously looking for air bubbles.

OK, you have the "leaded" distributor. If it's in good condition that is a major plus point. 3D is even better, giving better part throttle torque and lower fuel consumption, but only if you have a suitable map; it's far more expensive and requires extra work (such as a crank sensor) to fit so that's a matter of choice. If you just want to convert your existing dizzy to electronic, I've used Lumenition for forty years and have never had a problem when correctly fitted. I've not used the ignitor so cannot comment either way.

I'm assuming that you're wet sump! If you're dry sump it won't work at all. If you try it, I'd be inclined to remove the sump plug afterwards to see how thorough it has been.