what is actual comp ratio on a stock 67 442 with a 400

 

The advertised CR was 10.5:1. Actual CR from the factory is usually a couple of points lower, as the heads typically ran on the high side of blueprint chamber volume. This was to allow the heads to be surfaced when being rebuilt and not push the CR up too high. Of course, if the engine's been rebuilt, all bets are off. Milling the heads increases CR, but if the stock steel shim head gaskets are replaced with thicker composite gaskets, the CR will be lowered.