I have replaced following in the last 6 months just because the car sat 10 years before I got it: points, cap, rotor,wires, plugs, rebuilt the carb, fuel pump, fuel line, fuel tank. Issue shows at mid to high range not under load. Hot or cold does not seem to matter. The intake has stock exhaust heat.
Driving it it is not as easy to notice. Just reving it. Last night I noticed that #4 plug was black as if gas fouled. I cleaned the plug and swapped it with #5 and replaced the wire on #4. Ran the engine 30 min or so and the plugs looked fine... but my issue is still there. I tried restriction on the breather and no change. Car does not smoke a bit..... so no oil issues. I do have a pop (irregular puff of exhaust) every few seconds in the exhaust at idle.
Thanks for the help, Clyde
