|Getting closer to diagnosing the problem now, I think. The problem seems heat related, so it could well be a carburetion problem.
At the moment, I am running the car without a radiator fan, which works fine as long as I don't get myself stuck in low speed traffic. I will install a Kenlowe fan as soon as possible, but it has to be shipped from England. The trouble seems to start if I allow the engine to get hot without moving, if the temp needle goes above the normal level, misfiring begins.
Part throttle works fine, floor it and it goes dead (as in nothing). Obviously, the idle circuit works, but for some reason the mains refuse to come in. Would the reason for this be that the intake air is too hot, or is it the fuel that is the problem? I will build a cold air intake system, but I haven't started cutting the radiator bulkhead yet.