Quote:
Originally Posted by Tim Radley
Depends on the cam profile. A 13mm lift cam may have more piston to valve clearance than an 11mm lift cam. Depends on duration and ramp rate. Lift at TDC is a good indicator but not the gospel. Closest point of contact is circa 10 degrees off TDC on most engines.
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Well, this is not as accurate as it should be. A 13 mm cam will always bring the valve closer to the piston, all else being equal. Ramp rates and duration play a role to the relation the valve has with its seat, not with the piston.
If you are referring to the valve to piston clearance at TDC, then this is a whole different story and it has to do with the actual valve timing ground into the cam lobes or what is dialed in with the cam gears...