New to Me 1968

Dustoff248 said

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The '68 has a 318 and a 727 automatic. Understand that the most popular build for the 18 is 0.030 over, flat top pistons and a Zero clearance head, undestand that makes a high revving , stable 340 ci. As for the 727 they tell to put in a couple extra springs. Does that sound correct?

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318 and 340 have same stroke at 3.31”

A 318 has a 3.91” bore, and 340 has a 4.04” bore. That is a difference of 0.130”. You can’t bore a 318 that far. A “30 over” 318 is only 323ci.

A popular combo is the 0.030” over 318 with a 4” crank. That is 390ci.

Even better is a 0.030” 340 block with a 4” crank, that is a 416ci combo.

If you are building a street engine you are not going to rev very high the 390 would be fine. You will find an argument that the larger bore with the 340 block will breath better because of how close the valves will be to the cylinder bore with the 318 block… but a mild street engine that may not be a big deal.

All depends on application and budget.