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What are the rules for this 906 heads,,?? Valve size,,, runner volume,,, external modification,,, ??.
We work on NHRA Super stock cylinder heads, is it the same rules?



Must be original castings-no external mods...Pretty much everything else is fair game. Runner size, port volume, combustion chamber size and configuration, valve size, rocker type, etc all can be whatever works. No valve cover spacers. Must retain stock covers.

MB