flythe76

my son had someone put a set of gt-40 heads on his car. 86 with dished pistons, highlift cam. 7 out of 8 pistons hit the valves. i tore it down and put rhe heads he had on it back, e6sz's. now the car has about half the power it had before putting the gt-40's on it. any sujestions.

67mustang302

What size valves, what cam etc. Were the heads milled? Was the block decked? And was it a shop that installed the heads and cam, or a friend?