Copper head gasket trial

Ever notice how thick the head gaskets are on Briggs and Stratton engines? I decided to fabricate a head gasket out of 0.020" thick copper using the old head gaskets as a template. In order to keep the edges of the copper gasket clean and smooth I kept it sandwiched between two pieces of thin wood and used a drill press to drill the bolt holes. I also annealed the copper before use. Measurements were taken before and after with a compression gauge with a fully warm motor. The motor used in the test was a brand new (old stock) 4hp motor with no modifications. As you can see there was an improvement of close to 20 PSI in compression.