Have a '54 235 still 6 volt that runs smoothly - but when I turn off the key after the engine is well warmed, or after a drive I have no spark until the engine cools down again. If I don't shut off the engine it runs fine, but as soon as I shut it off I cannot start it again, there is no spark. Have had the carb professionally rebuilt, have replaced coil, plug wires, distributor cap, rotor and condenser. Vacuum advance is working fine. Timing is good. Have checked for a short where the negative lead goes through the distributor wall - has no short that I can detect. I've tested the ignition switch. Another thing that is driving me nuts and may be related is that after warming up the engine, when I set the dwell, as the engine keeps running - say 20 minutes, the RPM slowly changes (faster or slower, no discernible pattern) and the dwell (usually) increases. I'm at wits end. HELP!!!
