Compression ratio question

[kenneth j hanawalt]

Excellent info Schurkey. Thank you for that!!
Ken

 

[badco]

https://speedmaster79.com/tools/engine-compression-ratio
With a 4.030" bore and 3.480" stroke, a 64cc combustion chamber, flat-tops with 7cc of valve reliefs, a .041 head gasket, and an undecked block putting the pistons .025" in the hole, you're looking at 9.57:1 compression ratio. Nearly the same specs as my low-buck build. If the combustion chambers actually measure out to 66cc, you're looking at 9.37:1.

The factory lightweight flattops like the tuned port or the lt1s had are around -.005 in the hole without decking block the block. Ive done 2 vortec truck engines with 93-97 lt1 rotating assembly's and both poured volume worked up to be 9.9ish with a skin cut vortec heads that were 64.2-64.5cc .028 gm gasket that has a 4.060 round bore and pistons were .004- 006 in the hole. Pretty much identical to a lt1 except heads are a little bigger cc. Gm lightweight pistons, rods, and crank are tough and last but rings are a little expensive