quick run down , bought a 1650 gas didnt run , found it had burnt valve , cyls. look good so rebuilt the head put back on got 175 lbs . compression in all cyls , holley distributor was worn out & do to lack of parts for them replaced with a new delco style ,no vaccum adv., from Korves , replaced plugs , wires , set timing to TDC @ idle / runs close to 22 deg. @ 2000 RPM's. , got her all running but cant get idle down to 500 like it should be , lowest it will go with out shutting off is 800 , so i rebuilt carb , which is in good condition , soaked in new carb. cleaner for a day , made sure all passages where open with a small wire & air gun , installed new kit,but couldn't get main jet/ suction tube out didnt want to break it & kit dont come with it anyway so left it in. anyway installed back on engine runs better but still cant get idle down lower then 800 , also if you run it wide open & pull it back to idle it will sometimes shut off & if it dont it will stumble to remain idling for a min. the smooth out , but other wise runs great. I have tried moving timing some , tried moving carb. adjustments , but cant fix this problem. also it idles the best with carb. idle screw turn in all the way , id think it should shut down at the point wouldn't it ? not that it should matter but i went throw govenor & reset likage to spec. works great as it should ,but dont really have anything to do with idle since its held in the off postion at that point. what do you guys think the next step to try should be , is it in the carb.? maybe the new distributor is causing this do to the lack of vac. advance ? the 1600 didnt have vac. adv. & had no problem , but ive tried more advance didnt help. sorry for being long winded but to get any help w/ this i need to be as detained as possible , ive got lots of engine experience but this one got me .