Baqk to the 18:1 CR ratio. When I decided to lower my CR I bought some Zollner pistons off of E-Bay. Excellent pistons and they would have dropped my CR to around 20:1. Too bad the machine shop decided to ignore my written instructions and force me to move to a larger set of pistons. I went back to Peter Bierman's article of how he measured his final CR. The heads I bought from CCH had a larger precup area so I decided to CC the heads and Ricardo cup area. Wound up with 29 cc's for the head, 4 for the piston ricardo area and area from piston ring up, .010 gasket and piston depth(machined .020 off and ceramic coated) at -.018 gave me another 15 cc's. 820 + 48 / 48 gave me around 18.1:1. I also reduced my height of the pistons by relocating the pin bushings .010.

I'm glad that I had to do some measuring after the machine shop so efficiently hosed me over because my CR might have been much lower had I gone with true 18:1 pistons. Lots of ways to get down there and my method is far from the ideal setup but was born out of necessity.