I am begining to build my new motor and am looking into some problems. I have the L31 short block and vortec heads (64cc) this gives me 9.0 to 1 I would like to raise this up to 9.5 to 1 how much would I have to mill from the heads?


Thanks
Brian Felts

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1989 Camaro RS

305 .030 over Hydro Pistons
Vortech heads milled to 58cc...Performer RPM intake....LT4 cam..Crane Gold rockers...FastChip custom chip...ALum. Driveshaft...3.73 gears with Posi...underdrive pullys...Rebuilt 700R4 with Vette Servo and B&M shift Kit...MSD ignition...A/C Delete No SMOG junk....1997 SS leather interior...B&M Shifter... Ultimate TBI mods...14X3 K&N open Element Non-Drop...Hooker headers....3" exhaust with Flowmaster Cross flow 16X8 Wheels from 97 RS Spohn LCA's Spohn Panhard Bar..LETS PLAY FORD!!

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[This message has been edited by Brian Felts (edited November 27, 2001).]

 

1 cc is approximately a change of about .14 points. So, about 2.5-3cc. Now the trick is how much is 2.5cc on a generic head?

I would say no more than .020". Too many probs if you get it wrong to go more than that.

[This message has been edited by jcb999 (edited November 27, 2001).]

 

If you have the block decked and use flat top pistons, that should give you high compression. Now sure how high. Chevy High Performance built an engine like that and included a compression ratio chart in the story. I'm not sure which month it was, but I'll try to find it. I believe it was about 6 or 8 months ago.