Quote:
Originally Posted by Rory McNeil
On my 390/427/428 FE Fords, I have always blocked the exhaust crossover opening in the intake gaskets with a piece of an old butter knife, trimmed to fit inside the slot in the gasket. I have tried the gaskets with the unopened crossover holes, but they always burnt thru in short order. I always found it interesting that NHRA will not allow you to fill the head passage down into the bowl, yet the approved Edelbrock heads have no provisions for the crossover passages at all, but thats OK.
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NHRA will allow you to fill the passage as long as it does not extend into the bowl and make an extension of the port ceiling surface. I used Plaster of Paris poured into the crossover passage to within about 1/2" of the port. Usually wadded up tissue stuffed into the passage from the port side served as the boundary. Once it was heated, it was like ceramic. Never had a problem.