what is the carb ?
What is the vacuum at idle in gear ? recheck torque on intake bolts & carb bolts , make sure the carb gasket is the right one as some will not seal to various intakes .
I assume the idle speed is unstable also so it could be vacuum advance or the advance weights in the dist messing with it at idle .
I was tuning a six pac one day & it would idle at 500 rpm , if you brought it up at all it would idle @ 1200 , nothing between finally after trying everything with the carb found the problem in the advance weights , they would move substantially at 510 rpm & change everythng
Chryco it's a profrom 650 vacuum secondary electric choke unit, you were trying to help me Tune it in another post. I was following the directions in that post but I'm back to questioning my vacuum because the trouble shooting section on the holley site seems to put that as the common "issue" I'm trying to eliminate issues one by one. Fix what I know and can easily tell if it's good or not.
I Have never messed with Idle weights before, I'd be lying if I even knew how they worked other than they control advance/ retard by centrifugal force, but no idea how to adjust those or even check if they are working correctly?
Vacuum is between 15-18 PSI but in park at idle.
the carb gasket is a brand new square (meaning one big hole not the 4 individual round ones, or 2 holes that separate the primaries from the secondary's) rubber unit from fel-pro I believe, with no spacer. Profrom carb is an aluminum base.
for AARTA340, the motor is new to me, it's a 72 360 with a rebuilt by a good engine shop a few years ago. It sat unused for the last year as the owner of it died and his son sold it to me.
the propane torch scares me not going to lie but I will give it a go.