Stock valve sizes, at least through 270 is Intakes 1 5/8 (1.625) Exhausts 1 3/8 (1.375) California Bill called for Intakes of 1 15/16 (1.9375) and Exhausts of 1 11/16 (1.6875). I'm not sure if the 302 stock valves were the same. The 302 was pretty new to the hot rod scene when California did his book. We sorely need a new GMC Speed Manual that covers all the specs and old race tech as well as new tech from MOPAR main seals to turbos and fuel injection. It would even be a great help to be able to easily retrieve the wealth of information buried on this site and molding away in stacks of the TPN.
