318 combo's

67-68 blocks can go .090 over.. custom cut gaskets for the little teen. a 340 head gasket would loose 10cc or more a cylinder... kb67 pistons or the forged Kb .. people over cam the motor a stock 340 can is big for 318. run a 2 1/2" dual exhaust to the muflers then 2 1/4" to 2" tips... I put a 2" reducer just past the h pipe or x pipe inside the 2 1/2" pipe as a baffel I run a headers. Off a stock manifold run 2" duals.. or you loose back pressure and your bottom end power... unless your racing restrict the exhaust to 2" outlets I have 3' mufflers to make it quiet but flow.. the cherry bomb looses power whereas you're grandfather's quiet one makes more power..