I am very familiar with this issue having suffered with it in both my Mustang and Bronco. When parked after use, heat radiating off the exhaust manifolds, and conducted thru the intake will boil or "percolate" fuel flooding the motor.
First, make sure float setting is correct and needle valve seat is perfect. Not uncommon to see the fuel line against the block become so hot it pushes fuel past the bowl seat. Add a phenolic spacer between the intake and carb. 1-inch thick if you have space, or 1/2" otherwise. Block off the exhaust crossover in the intake. Run the fuel line away from the block to keep it as cool as possible. Use a fixed blade fan without a clutch. Same as short track modifieds. Keep as much cool air as possible moving thru the compartment when running. Cooler it is before parking, cooler it will be after. Don't be ashamed to open the hood when parked. Is a honor sign of hard core street racers.
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