[Rich Biebel]

Cast iron rusts very quickly and always has. Your headers allow moisture/condensation to get in their especially when the exhaust valve is off it's seat.

Hold the carb wide open after a race and use MMO or ATF or WD-40 and crank the engine over to draw the stuff in past the carb.

I used to use a rag to absorb the gas from the carb accelerator pump.

Stuff rags in your open headers or find a plastic cap that fits..

Plastic Caps from various pipes might work....they protect the threads on new pipe and once you have the right size.....they work perfect....

Exhaust seat/valve rust was always a problem.....