Stage 1 V8,seems to drop 4 cylinders when hot

Hi,I have started a new thread because my original problem is fixed......won't start,and stopped if key let go -put new ballast resistor on,and it drove great..75mph with ease! ~~~~~~ untill it got warm? then it seemed to drop 4 cylinders,and struggled to do 30mph!

I have had this problem for a while,and thought the Ballast Resistor had cured it,but it never. It starts and keeps running,so ballast resisitor is working, but after about 3 miles it suddeny seems to drop 4 cylinders,and struggles to pull even 30mph!:doh:

I have just started it up,since left overnight and it fired up first turn,with no acceleration, just using the choke.It revved a lot better, but it still seemed like it was on about 7 cylinders,(which is an improvement to the 4 when hot! ). Any suggestions as to the cause are more than welcomed.

I can't say for certain but have you checked the spark plugs are the right heat grade? i had a similar problem years ago with a highly tuned golf gti.

It had been rebored with forged pistons, wild cams and other things and was pushing nearly 200bhp from a 1900cc engine. It was running like a bag o ****e for a month or two after it had been rebuilt and I took it to a few specialists and the one who fixed it started telling me about different heat grade spark plugs for tuned engines.

He said it was more common on turbo charged cars but if your engine has been breathed on it might be worth a try. Not sure how you would go about getting some different plugs with a higher temp grade because mine had to be ordered, but it could make sense from what you are saying about it happening when warm.

best of luck with it anyway, sure it'll be something and nothing

Stage One, quite a rare bird these days. Seeing as how you've got carbs then an ignition fault would seem to be on the cards, plug suitability (as mentioned) & the quality/condition of the leads would be my first call. A (genuine) dizzy cap replacement may help & the fact that it's missing on individual cylinders would tend to eliminate items that are responsible for running the lump itself i.e coil, king lead, rotor arm etc.