Vac advance will work fine on ported or manifold, but it needs to be set up and tuned specifically for the method used.
Personally I used manifold vacuum on my truck. From memory, I have ~14° initial, plus around 20 mechanical (reduced/limited from what stock allowed), plus another 15ish via vac advance. During cranking it sees the initial 14 and starts well, then goes to 30 something. At part throttle cruise, they all add up to ~50 something. At wot, the vac advance drops out to the ~34 total.
Works great, and really cleaned up my idle.
You know, this seems like a great recipe well worth trying out. I can certainly appreciate cleaning up the idle situation, my 360 with just a 238@0.050 duration struggled with this for a long time. I re-worked the Carter TQ circuits which greatly improved this, but I bet there is still a little more left in there given that the engine would run ever-so-nicer with more advance at idle, and yet the problem with startup with that much initial advance would prevent me from going further.
Nice setup!
