My RPM's are milled .050 and they will go more than that. On my old motor, i ran shims, copper coated with these heads for around 2 yrs and didn't have a problem. Mick
69 Dart GTS 440 mopar .590 cam, Edelbrock heads, 3200# best et 6.45, 106.78, 10.14, 132.88 mph, 1.47 60ft best 60ft 1.36