70 318 with 340 internals/Cyl Head

Dartswinger70 said

what they need is a good 318 piston that is 68-71 340 style high comp. I'm sure they may have 'em but then again maybe not...also is there an issue with a 2.02 X head valve hitting the cylinder wall? i really don't know I have 340s so never had to try and "convert" a 318 into something hot.

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Good pistons for 318's are available. But at the end of the day you have to build to what octane gas you want to run. The only SBM that needs bore notches for 2.02 intake valves is the 273. 1.88 intake valve 340 and 360 heads work well on the smaller engines and flow almost as well as 2.02 intake valves. However it never hurts to check valve clearance at max lift plus a safety factor.