Setting deck height for 9:1 compression Options

[Chad911sc]

I have my short block built and I’m ready to set my deck height. It’s 96mm bore with stock 71mm factory crank. This is a 2.0 2056 build. I have a Web 86a cam calling for approx 9:1 compression. I have 60cc heads with 3cc valve reliefs on my flat top pistons. If I plug all this into the calculator, I get 8.3:1 for my compression ratio if I set the deck height to .040 inch
After I set up the piston on the rod and bolt down the cylinder to the block, I get .053 inch from the piston to the top of the cylinder.
My question is, what is the best way to proceed to get the 9:1 ratio with at least .040 inch total deck height.
I am thinking that if I take off 6 total cc’s from the head, that will leave me with 54cc heads with the 3cc valve pocket = total 57cc’s. Bringing me now to the correct 9:1 compression ratio with the .040 inch deck height.

If I am in the right ballpark, this means I need to have my heads fly cut….correct??
If this is correct, how do I go about calculating how many thousands of an inch do I need to have removed by the machine shop to remove 6cc from the head?

I obviously will need to remove at least .013 inch total deck height get to my .040 goal, and that’s with no shims or head gaskets being used.

Thanks for your time, Chad

[technicalninja]

Drop dead simple...

Set up dial indicator so it replaces the pushrod into the lifter.

Rotate engine through 720 degrees.

You will notice needle movement through whatever degrees duration the camshaft says it has. Let's say 300 (big cam). the other 420 degrees is the base circle, and the needle movement should be VERY small if it is noticeable at all.

For use with zero lash the "runout" or variation should be .0002" (two ten thousands) or less.

Many dial indicators don't read that small.

What you are looking for is a solid needle during the "not on lobe" or base circle portion of the rotation.

My stock cam had somewhere between .0022" and .0024".
You would definitely see needle fluctuation with this much runout.

I'd check lift during this procedure as well. Tip of lobe to base circle multiplied by 1.3 should be very close to what the cam card says for lift.

Watch Karr's videos on setting up both pushrod length and rocker arm geometry and shimming. Good stuff!

Edit: You can find ultra-accurate dial indicators; they are expensive and "finicky" to use.
A normal cheapy version will work fine for this. Most are good to .0005.
You should see almost no movement on the base circle.