Compression/head gasket selection. 360

jtn2655 said

I'm building a 360 for the street/ occasional track day, Edelbrock Performer RPM aluminum heads (63cc chamber) KB 107 pistons (+5.00cc), block bored 30 over, xtreme energy hi lift cam 231/237@ .50
edelbrock RpM Air Gap intake, holley 750 carb and summit racing 1 5/8 headers.

Just got block back from machine shop and was running through my compression calculator. With a .050 fel-pro Gasket I will be at approximately 10.54:1. If I step it up to a .060 head gasket it will bring me down to 10.3:1. I will run on 93 octane. Will the thicker head gasket cause any problems?

Click to expand...

I just ran your numbers as best I can with what we know, and I get a CR of 10.4398 just as it sits.

That’s making two big assumptions. The first assumption is the valve notches are only 5 cc’s. I doubt they are that small. The other big assumption is deck clearance. I did your math, which I will outline below at a .0000 deck clearance. If your piston is below deck (which it probably is) that will make the above number lower than what I’ve posted. And, if the piston is above the deck (highly unlikely) then the above CR will be higher than what I’ve posted.

Here are the number I have.
Combustion chamber 63 cc
Piston volume. 5 cc
Head gasket volume 11.270 cc
Deck clearance .0000 for 0 cc
Swept volume 748.293

So the math is:
Chamber cc+ head gasket cc+ piston cc+ swept volume

That is divided by:
Chamber cc + head gasket cc + piston cc

That means it looks like this:
63+11.270+5+748.293=827.563 and
63+11.270+5=79.27 and then it’s...

827.293/79.27=10.4398 CR

Again, that’s assuming a .0000 deck clearance AND 5 cc piston notch volume.