Are 340’s rare

Yeah, you are 100 percent right, the 340s are a whole . 049 inch larger bore then 318s. Not remotely true, yep, thanks for that correction, your the man.

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I'll say it again, it's also about bore to stroke ratio.

My math says 4.04 minus 3.910 is .130 and not the .049 you calculated.

That's over an EIGHTH of an INCH bigger bore. That's a big thing.

I'll take RPM over stoke length any day.