Degree a camshaft.

And finding true TDC. I've seen TDC marks farther out than 9 degrees. Wonder why your "tune" isn't as sharp as someone else's?

....and I firmly believe this also explains how some engines "mysteriously" ran better than others from the factory in the muscle car era. I can remember several cars when I was growing up that just flat out hauled more *** than others. Same car. Same engine and transmission. Same gear. I don't think the factory ever degreed cams in. Some were simply closer than others.