First I know its called something other than a back fire if its popping up from carb, cant think of proper term right now.

Last night drove the cutlass to work, warmed up drove no problems performed great.
Got off this morning started car took off before fast idle had finished but didn't figure would be too big of deal. Now I could tell the choke had not finished opening all the way but was running fine.

pulled away from first light and under anything outside of very light acceleration it would pop out carb. This continued for about 6 miles or so then she was running perfect again?

now curious to opinions, I was thinking maybe bad or old gas. The car had been sitting for about a month or more waiting on brake lines. But filled up monday and drove around for like 20 min no problem, drove this am for 20 no problem, and after the 8 min situation drove the other 12 min home perfect.

any ideas?

 

Usually a backfire through the carb is an indication of timing being too far advanced. The flame will travel back past the open intake valve and into the intake. I'm not sure that's the case here though. I would check your ignition system thoroughly. Make sure points are set correctly, condenser, cap, rotor, wires, coil and plugs are good.
Being you drove home this am could there be condensation causing a arc on the wires? One way to check for bad wires is to have it running in the dark with the hood open. If you see a glow around the wires or even a spark to ground then you'll know. I'd start there before I'd think the carb or anything else.

 

Could be a lean backfire - choke coming off too early leaves the mixture too lean, causing lean popping, resolves when all warmed up.

Is your exhaust crossover blocked?

- Eric

 

I agree do not believe it is caused by the timing being too far advanced in this case.

working the graveyard shift, sometimes my common sense has trouble turning on around quiting time after night of work. As soon as I read your post about checking the ignition system this evening light bulb came on.

It was very humid this morning, so that in addition to just being early in the am probably was some condensation on ignition components. When i left for work i was pulling out of garage so humidity probably wasn't a variable and hasn't been in my previous drives since thats where i start and finished. Parking at work it was exposed to elements.

So tonight, if time permits, will go down to garage with spray bottle pop the hood with the lights off and spray around components. Just checked plugs recently and they look good, wires, cap, and rotor are fairly new ( sept 2010) but that never means anything.

Will report back my findings.

thanks for your help jumpstarting my mind

 

The carb is brand new and actually the choke is comming off to late didn't have time to adjust last night just wanted to drive her will be adjusting tonight before i start further diagnosis.

 

well life has had me busy lately, but finally got to inspecting further. There were no problems with wires however when inspecting cap and rotor, found a bit of carbon tracking. decided to just go ahead and replace.

drove to work and back last night with no issue. Seems like this may have done the trick