I have a 509 ci 575 HP GM motor. I was told from the previous owner that the motors had solid lifter cam. the problem is he did not have the cam specs so i can't check the clearance on the intake and exhaust values. Is there a rule of thumb for adjusting the values with out the cam specs.The motors are carb if that makes a difference.

Different cams use different lash, you really need the cam card.