318 Build.. Zero Deck or Stock Deck Clearance?

318willrun said
I think true compression ratios on 318's without the 302 heads would average 8 to 1 up to 8:4 to 1, pending on head cc and how far down the hole the pistons are. Lets say his is an 8 to 1 motor. Ok, add the .030 over KB pistons he selected. Compression, without doubt, has risen. Now throw the closed chamber mag heads on there, and without doubt, compression has risen again. I don't doubt for a minute that a true 9 to 1 motor here lives, and that could be checked. It may be even higher.

Look, deck the block, I'm all for it, Just say'n to get a compression ratio for the street, I think he is already there... Check the compression now, he may be at 9:3 to 1 as it sits.

My point is that you have no idea unless you at least measure it.

If he ends up with actual 59cc chambers, runs the KB167's and ends up at .010" down and uses a .026" gasket he could be at 10.2:1. Even with a .039" he could be at 9.8:1 with those specs. But without measuring the decks or the chambers he could just as easily end up at 9:1. Or even 9:1 on the left bank and 9.5:1 on the right, a .010" difference on the decks would be all it takes. And that's where it gets tricky, because if you calculate it for 9.5:1 and end up with one bank at 9.5:1 and the other at 10:1 because the decks aren't square with a mild cam it won't run on pump gas anymore.