Robert: Forgot to answer one of your Q's: I run 20 degrees initial on manifold vacuum. Distributor is set up for that and if I remember right it will idle at 28 degrees. It will instant drop to 20 when opened up. Total is 35-36 all in by 2.500 rpm.
Your distributor is hooked up to manifold vacuum, and not ported, correct?
What is your vacuum in drive?
At what vacuum does the vacuum advance start advancing?
If vacuum in drive is below where the vac advance engages, you
will have issues, particularly when cold. If that's the case, you'll need to use a hex key in the nipple of the vacuum can to lower the point that it engages, to prevent that overlap.
Easiest way to test this is with a mity-vac and timing light, or just take the distributor cap off and watch for it to move.
