step one. .get a bottle of white out, or other bright colored paint.
step two, find the mark on the dampner ring.
step three.. fill the groove with the marking compound.. wipe off excess.. this makes seeing the timing mark so much easier.
step 4, disconnect vacuum advance and plug.
5) clean the timing tab off.. figure out which mark is the ZERO mark. .makes life easier.
6) start the engine.. point the gun at the balancer and timing tab.. look for the line.
look at the timing mark that the line lines up with..
the strobing effect of the flashing timing gun will make the mark appear to sit still, even tho it's spinning on the crank.
set your 'base' timing for about 10 degrees.. this is a good safe place to start.
then test drive.. if it doesn't ping.. add more timing.. repeat until it starts pinging under heavy throttle.. once you reach that point.. back it off a couple of degrees and lock it down.
if you have an 'advance' gun that you can dial in the timing, then you can set your timing by 'total' timing which tends to be more accurate..
figure out your timing you want.. say.. 38 degrees.. set the gun for 38 degrees...
have a parter rev the engine to 3000 or higher.. whatever it takes for the timing to stop advancing.. 3000 is usually enough.
adjust the timing so that the mark on the damper aligns with the 'zero' mark on the tab (since the gun is already set for 38)