Workmonster Racing Engines     |   home                      Porting 28 Typical valve prep. Intake face is .010 large on OD than seat, .010 smaller on ID. Backcut on 20 degree angle. Angle can vary, depends on the valve. Exhaust maintains same dims as intake in relation to seat. Backcut may or may not help. This particular valve has none. Valves are SI brand, a good, economical stainless valve, and made to fit Ford heads much better than Chevy valves.