Does this sound like a carb tune problem or a trans problem?
 

So, been driving my 86 Iroc after finishing up my Carb swap and I am having the following issue and need some thoughts on where to start digging. Car is a 305, originally TPI swapped to carb and has edel performer manifold and holley street avenger 570cfm, Comp Cam 260h cam, 700R4 trans.

I am having a pretty decent stumble / miss fire just off idle during acceleration. Ive noticed it gets worse the longer I sit, a simple stop sign is less of an issue, a longer stop light creates more of a stumble. It appears that if I give it more gas it corrects the stumble and while cruising there is not a miss/stumble. Ive also noticed that at longer lights while idling Ill start to get a miss fire in the exhaust at idle. Car never dies and no stumble when rev'd in park/nuetral.

Im leaning towards carb tune issue because I never tuned the carb during the swap bc it ran, but, Ive been reading up on Torque converter issues causing spark knock, and I am leaking some trans fluid when the car sits for longer than overnight which went on long before I carb swapped.

Re: Does this sound like a carb tune problem or a trans problem?
 

It sounds like the carb is loading up at idle, in gear. Try doing an idle drop adjustment with a vacuum gauge and double checking the initial timing to make sure it's not too far retarded.

Re: Does this sound like a carb tune problem or a trans problem?
 

I will try this, Thank you!!!!!

Re: Does this sound like a carb tune problem or a trans problem?
 

i had a vacuum leak that pulled this crap on me a year or so ago.

Re: Does this sound like a carb tune problem or a trans problem?
 

If that all checks good, check to make sure you are not running too much fuel pressure to that carb.

Re: Does this sound like a carb tune problem or a trans problem?
 

did you switch your distributor with a non computer controlled one? if not that could be your issue

Re: Does this sound like a carb tune problem or a trans problem?
 

Yes, running a non computer distributor, I thought it might possibly be a spark issue, but have ruled that out.

Re: Does this sound like a carb tune problem or a trans problem?
 

Right now I am running 6psi from the regulator to the carb, does that sound too high?

Re: Does this sound like a carb tune problem or a trans problem?
 

no, that sounds perfect for carbs, is that at idle or WOT?

Re: Does this sound like a carb tune problem or a trans problem?
 

checked the pcv valve lately?

recently had the stumble scenario at the lights, ordered a new one and pulled the old one to compare, completely screwed. might not be a bad test for $5

Re: Does this sound like a carb tune problem or a trans problem?
 

Idle, havent checked WOT.

Re: Does this sound like a carb tune problem or a trans problem?
 

Im not currently running PCV, just running 2 breathers instead. Any chance a PCV set up would fix this? I was under the impression either set up would work, but the PCV was just "cleaner"

Re: Does this sound like a carb tune problem or a trans problem?
 

nah probably not, the valves going out do all sorts of wierd stuff.

Re: Does this sound like a carb tune problem or a trans problem?
 

4 to 6 psi should be fine.

Re: Does this sound like a carb tune problem or a trans problem?
 

Check your ignition control module (ICM) inside the distributor cap. Whenever mine is going out (these cars eat them like candy) I get the symptoms you describe.