setting timming and distributor vacuum advance problems????

[1st_charger]

OK on my 383 I set my idle at 1000 rpm! I'm running a carter AFB carb. The engine is pulling 10 inch lbs of vacuum. I set my timing at 15 initial with the distributor advance plugged. Plug in the distributor and look at timing again now it's up to 30 deg. I have the distributor plugged into the timed vacuum port on the passenger side front port on the carb. Is it doing this because I'm off the idle circuit or is there another problem? I've switched the distributor vacuum source to the driver side manifold vacuum and it doesn't seam to cause the distributor to advance like the timed vacuum port does. car runs pretty good but I dont think this is right! any help is apreciated this is my first engine build along with everything else on this car!

Specs! 9 to 1 comp 383 30 over
Mp electronic ignition
Carter AFB electric choke
MP 284 484 cam
3000 stall converter
452 heads 2.08 1.81 valves
Edelbrock performer intake
Headman elite 1 7/8 headers

[Chryco Psycho]

set your timing around 15* at idle with the advance plugged total timing should be in the 36* range
leave the vacuum plugged & go drive the car

[Plumcrazy]

Having the throttle open too far can cause the timed vacuum port to have vacuum at idle.  But you say hooking it to the manifold vacuum port on the drivers side doesn't advance the timing, then you don't have manifold vacuum there.   Hook a gauge to that port and see if vacuum increases as you rev the engine.  If it does, then just use that port for your dist vacuum supply.