Having a little trouble getting my tune right and I am wondering if it has anything to do with the vac advance.

I'm using a stock style HEI set at 12* initial. When I plug in the vac advance and use the ported vacuum from my carb it goes up to 28* at idle(1000rpm, 9hg of vacuum). Do I need an adjustable vacuum advance or is something not right here? I will be bringing the idle down to 900rpm but its pretty cold here right now and has been hard to keep running well at any lower than 1000.

That's 16* of vaccum advance. Are you sure your going to the ported vaccum port? I absolutley never use ported vaccum, always use full manifold vaccum. You should verify when your mechanical advance starts to kick in, that could be part of your problem if it's starting at to low of rpm. Say for instance your car idles at 650rpm's in gear and 850rpm's in park, start your mechanical advance at about 1,000rpm's; this way it wont ever interfere with your idle. I DO have an adjustale vaccum advance so that I can run 18*initial plus 11* of full vaccum which = 29* timing at idle, so you should be able to make yours work with 26* timing at idle. Good luck!

10 Degreee vacuum advance Borg Warner Part# V482 available at most parts stores should help and allow you to run more intial advance. Try experimenting both ways with ported and full vacuum.