Something doesn't seem quite right. Check your paperwork from Koffel for retainer to seal clearance. I would be running a cam at a little over .600" lift with a head that is flowing 272 @ .550. I'm working on a set of 346 heads with stock length valves that are flowing 274 @ .500, 295 @ .600, 303 @ .700 and they have .870" retainer to seal clearance. If you have the retainer to seal clearance go to at least a .600" net lift cam to use the full ability of your heads.
