Looking for help

[cliff987]

Hello,
 I have a new to me 1981 Turbo Trans Am and I am having carburetor issues.  The one installed turns out to be an early 1970ish QuadraJet off a Chevy and with the mixture screws fully in is still putting out black smoke, it was running pretty good but on the way to the DEQ station something broke and I made all the diesel trucks on the road feel a little inadequate.     So I was going to rebuild what I was told was the original carburetor and it turns out that it is from a 1985 Chevy; so strike two.

 I took the car to a local mechanic and as neither carburetor is actually the correct one for the car he suggested an after market.  He is suggesting an Edlebrock Thuder AVS 650 CFM, Edlebrock told him that it would work, is this going to have to much air flow for my 301 engine?  I figured a non-turbo engine would be happy with about 450CFM so I am worried about it running lean under boost.

What do you guys recommend, should I go with this and get it running right now or try and find an original and have it rebuilt?   Suggestions please....

[omaha]

I would not know where to start. Is it possible that the turbo went bad? If it is the carb, it is possible that the needle and seat is sticking or has some dirt in it. BTW, this is not the best set up as far as turbo;s go. Not the best design with the draw-through set up. Probably would have more power if it had a Pontiac 350 in it. If you gotta keep it turbo, I would stick with the Q-jet just rebuilt properly with the same specs as the original carb. Since the original carb is MIA, I would find a 76-79 Pontiac/Oldsmobile carb and rebuild it. Trying to find the original specs might take some time and I am not sure if there are any special components or design aspects of the original turbo carburetor that would be hard to replicate. Although, Im sure it can be figured out.  Also, with the screws tuned all the way in and you still are running rich? there is definitely something wrong there, wrong screws/spring or needle/seat is bad.

[Cliff Ruggles]

I would find a 301 turbo carburetor.  They are different that naturally aspriated carburetors as they route the vacuum to the power piston in from the front of the baseplate and use a valve to kill boost to the PP to keep from pressurizing it.

The calibration is also different that the N/A 301 engines....Cliff