When I was building "claimer" engines for round track cars we were required to run the 76CC "smog" heads as an "economy" measure. In theory, any competitor could buy someone else's engine for $1K . In practice, nobody ever did that, and we were all cheating on the buildup costs. I found out that by angle-milling the big chamber heads, the 76CC chamber became 60CC- - - - -higher compression than a 64CC double hump head, which was illegal for the class we ran. All the tech inspectors ever did was look at casting numbers. Ray Charles could have spotted the modification, if he knew where to put his fingers on an assembled engine, but the tech guys either didn't know what to look for, or deliberately overlooked it. Some custom whittling had to be done on the intake manifold to make it fit properly, so the manifold and heads had to be changed as a matched set when we built up another short block. Those engines actually cost us around $3K or more each to build.
Jerry
