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

[Chad911sc]

I understand what you are saying about the deck parallel to the crank is super important, this is why I disassembled it. And I am grateful that you have taken the time to help me see that it was necessary to do so. When I place a level across the deck it only has a .003 of a sag in the middle where Raby says it’s thinner. Some 2.0s need that much, but it doesn’t necessarily mean mine will need that much material to be removed. I also know I will need a shim under each cylinder when I’m done to set it back to .040 for final height. My question was more in the line of does .025 -.030 sound about right to get the head chambers down to the desired cc’s for the ratio I want? And also is that amount of removal typical for a fly cut? I have read through hours and hours of posts and some people say you shouldn’t even fly cut a type 4 head. But how else could you make the pocket smaller to get your required result and keep your deck height at the desired .040?
I don’t want to beat a dead horse, but I am a painter by trade and each and every step matters, which make me a bit OCD.