If I understand you correctly you were checking for piston clearance? Regardless of cam "degree" the closest valve/ piston occurance is NOT at TDC. You need to check probably 20* or so, I.E. rotate the crank "up and over" checking as you go.
I see what your saying. I was really just looking for a number and it made sense to look at it when the piston was at top dead center. The reality is, this cam was run for 8 or 9 years without making a mark, and then I swap the timing chain for a new one and now the valves are "machining" their own reliefs in the top of the pistons. How bad the clearance (interference) is, is almost irrelevant.
