How Much Can Heads Improve Compression???

. Unless you have about 9.5 or higher compression ratio leave those aftermarket cams in the box… they won't help.

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Wrong answer! I have a magnum 5.2 with 8.86 cr. Roller cam 210/220 @.050, 1.72 roller rockers that give me .538 lift. Ported magnum heads with 1.97 int valves. Engine dynoed 290 at the wheels. 3800 lb Dakota ran 13.27. So a non stock cam will work even with lower compression.