Depends on a few things. bleed off, Quench and aluminum heads make for a more civil compression. Mine is 12.5 and I can drive it (not race it) with the sh#t they call gas nowadays, but choose not to since all that STUFF added in makes for a dirty sick carb at the end of the day. I just mix with 100 unleaded that can be bought at some stations with the good Sunoco 112 grape juice as I call it.
