Valve clearances for stock and aftermarket cams

[minutemen]

Why is the valve clearance for aftermarket cams usually .006-.008 and the clearance for stock cams is .004-.005. I set my valve clearance at .006 and it makes quite a bit more noise and I would think is quite a bit harder on the adjustment screws and valve ends.Tony

[Billy Ricks]

I believe it's to keep from having valves float at high rpm's. Gives them more of a chance to seal before they get back on the cam. Plus a hot rodded engine is going to run a little hotter so clearances need to be just a bit bigger to allow for more expansion.

[saaz]

Standard cams have noise reducing ramps on the cam profile, aftermarkets don't need them. At least thats what the bloke who ground my cams said.