Actually that is not a good check. If there is not enough clearance, the intake valve would hit the piston, somewhere after TDC, and the exhaust would hit somewhere before TDC (or vice versa, I forget which) Checking Piston-to-Valve Clearance, the Right Way!
This is the way I do it, except I start checking about 25 degrees before, and keep checking all the way to the point where the clearance gets larger. A lot depends on the cam, and where it is degreed.
