Originally Posted by Custom10
When using a vac gage inside the truck...
FWIW, (and not that MY personal endorsement means squat) since the work you did to tune in the timing curve on your engine some time ago, you've gotten to be quite an authority on setting up a timing curve. It's not the easiest subject to convey and there are a lot of nuances that can make a relatively large difference that may be neglected by someone new to the deal. So I say good job.
I've posted the following about a hundred times, so once more can't hurt I suppose:
will allow you to be sure the timing tab and damper are correctly indicating TDC.
MAKE A TIMING TAPE
to see what the total timing is, w/o needing to use a dial back timing light. You can also buy a timing tape, get one that matches the diameter of your damper.