Diamond's Compression Ratio Calculator #'s

I gathered what firm numbers I have for my engine build and plugged them into Dimaond's compression calculator.

But when it comes to the Fel Pro 1009 head gasket's bore diameter, the hole doesn't look very round in my gaskets.

4.35" bore
3.91" stroke
6.89" rod
~4.39" average head gasket bore diameter
~.037" compressed gasket thickness
10.7109" deck height
.24" from top of 1st ring to top of piston
84cc Edelbrock head chamber volume
4cc valve relief in top of flat-top piston
.0009" distance from top of block to top of piston in hole
1.865" piston CH

10.68 to 1 was the result.

Would the Cometic 4.350" or 4.380" x .036" gaskets be a better option? the compression rises to 10.72/71 with those numbers.

Would the 4.350" bore gasket would be too tight?

Or would you just stick with the Fel Pros?

Thanks

http://www.diamondracing.net/tools/

10.68 to 10.72 is very little gain. I would consider a .030 gasket to get .039 quench keeping in mind PV clearance will need to be checked/dealt with if inadequate. A 4.35" bore gasket would be too small

Thanks Rob, but the piston is in the hole .0009", almost flush.

Wouldn't an .030" gasket make it .0309" quench distance?

Calculating-in an .030" gasket would bring the compression up to 10.85 to 1.

Correct, I missed that extra zero

Quote:

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Thanks Rob, but the piston is in the hole .0009", almost flush.

Wouldn't an .030" gasket make it .0309" quench distance?

Calculating-in an .030" gasket would bring the compression up to 10.85 to 1.

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.030 is to close for piston to head clearance, rock the pistons so you get the max. hieght at the cam side and then the motor mount side, make it have at least .035 clearance if you don't want the pistons hitting the heads, .040 is a lot safer on pump gas with a street motor