been there too
Know the problem well. The fuel it self is not the issue. The underhood temperature is causing the fuel to percolate in the bowl(s). The fuel boils over into the vents flooding the engine. Not so obvious when running, but will kill the engine at idle.<br>To solve the problem in both my '75, 4V, 12:5:1, 351C Bronco and '68, 8V, 11.7:1, 427 side oiler GT 500 used 1-inch tall, 4-hole, penolic spacers. If using tube headers problem is only componded. Adding a heat shield under the bowl(s) helps too, as does a high pitch, non clutch fan to move air thru the engine compartment.<br>Be certain to use a good quality (Felpro) gasket on each side of the carb spacers.<br>Understand hood clearance can limit spacer thickness. Thinner spacers, 3/4, 1/2, and 1/4 are available.<br>Engine builders use these different thickness to tune plenum volume.