Quote Originally Posted by Grumpy 427
I need to get something nailed down here, if anybody can help?

I have a calculated compression ratio of 12.3-1. that is with calculator.
http://www.rbracing-rsr.com/compstaticcalc.html

The heads are 122 cc the head gaskets are .039 the deck is .005 and the dome is 48. 4.31 bore x 4.00 stroke.

I did a compression test today, and 6 cylinders are at 195, one is at 190 and one at 200. I read somewhere that the max for premium 92 pump gas was 180 then add 1 point in octane for every extra 10 lbs of cranking compression. is this true or is there a real formula to base this on? I am running pump gas, and VP-C5 octane booster with 38 degrees total timing. I cant hear any detonation, and the plugs are not peppering.

Sheldon
That seems like a lot of timing to me.
There are a lot of variable's.
Cam profile,are the combustion chambers polished,piston domes ploished,spark plug heat range etc,.