TDC and Damper . Engine experts in 'ere

[shovelheadrob]

As Dave said some fancy timing lights don't like MSD, my Snap-on one jumps all over the place when it is set on zero, but if you put a degree of advance in it reads just fine. Gauging TDC from watching the valves open & close is not going to give you any great accuracy, it has to be done with a stop. You don't need to buy a fancy TDC stop, just smash the centre electrode out of an old spark plug & then weld a bolt in it's place that protrudes an inch or so into the combustion chamber.