I guess that doesn't make much sense to me. I was always told that TDC is when the Piston makes it to the top of the cylinder and you are able to stop it with a tool or something, I actually bought a tool for this from Jegs...It didn't screw in in the damn hole on the #1 cylinder though so that's why I stuck the smooth end of the drill bit in there. So what your saying is that my mark is just a little off? because If I were to split the difference my TDC mark it would still not line up with the 0 degree mark on the timing tab. I think I have the wrong tab but it still shouldn't matter because once you find the true TDC no matter what the tab says you should be able to set the timing accuratley as long as your damper is degreed correct?