[356RS]

Now to figure the compression ratio. First step is the Sweep Volume (in centimeters) Bore x Bore X Stroke x (constant) .7854, I came up with 518.364cc (V1)
The case cylinder base surface was milled .020" or .508mm so I started with a .50mm shim & a .25mm shim. I tried several different methods to get a consistent deck height reading and ended up using the Jo-Block method. So with a .670" piston dome height plus the TDC dome height of .869" using the Jo-Blocks gets 1.539" minus the 1.498" (jo-blocks) I ended up with .041" = 1.0414mm. Change that to centimeters and calculate the Deck Height Volume. bore x bore x .10414 x .7854 = 8.179cc (V2)
Measured all the cylinder head volumes and came up with an average of 89.9cc (V3)
Piston Dome Volume (V4) is two math steps. First install a piston into a cylinder on the bench, with the piston dome below the top of the cylinder edge measure the distance from top of cylinder to top of the piston dome. I recorded .171", add this to the known piston dome of .670" = .841". Convert this to CM = 2.136cm. So bore x bore x 2.136 x .7854 = 167.76cc. Step 2 is to calculate the Piston Dome Volume by cc'ing the cylinder with the piston installed as above in the first step. With the lab burette filled I opened the valve and recorded 121cc.
So if I take step 1 measurement of 167.76cc and subtract the 2nd step of 121cc I get 46.76cc (V4)
So 518.364 (V1) + 8.179 (V2) + 89.9 (V3) - 46.76 (V4) = 569.683
over 8.179 (V2) + 89.9 (V3) - 46.76 (V4) = 51.319
Equals 11.1:1 compression. If I did the math right that sum is too high for a street/some track use engine.