Common problem with GM OEM starters, especially with headers. The heat affects the solenoids.

It was recognised by GM even with stock components and in some cases the factory installed a heat shield. They usually get removed during the 40+ year history of our cars.

If you search the Tech archives here, you will find a number of solutions. The best, if originalty is not an issue for you, is probably the high torque mini-starter. Less of a power draw, weighs a lot less and provides lots of clearance for headers.

Fords never seem to have this problem as the starter solenoid is up near the battery.

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