Quadrajet Hesitation When Accelerating

[jbwolfe]

Hi all, I'm about ready to go out of my mind trying to pin down the solution to my problem. Here's the deal:

My 71 CST/20 has a 350 with a Quadrajet. When I bought the truck, it had a Rochester 2G. It ran fine with the 2G, no hesitations or anything at all.

I put a new intake manifold on, and bought a rebuilt Quadrajet. It was nearly un-drivable right away. When you would step on the gas, it would just completely choke out, now if you were careful, you could get it to go, and once you did, it had plenty of power at higher rpms.

I had a mechanic work on it, who replaced the accelerator pump and did some adjustments, but it still was terrible, better but still terrible. Me and a friend messed with it, and then I took it to a different mechanic. They worked on it, and adjusted the timing. This made it a little bit better. They said the Power Valve in the carburetor was the wrong one for that carb.

I've been driving it for awhile, but it is getting really irritating. So I was talking to the guys at the shop, and I ended up buying a used Q-jet from them for $50. They said if it don't work bring it back. So I put it on the truck tonight. Here's the results:

It fired right up, even without the choke hooked up, (another problem...). Once it warmed up to normal temp, I took it down the road. It's a lot better than the old carb, when you're cruising down the road there is no hesitation at higher rpms, and no back firing. Only when you are starting off or shifting. If you're really light on the gas it's not too bad, but if you put your foot into it even a little bit, it gasps and chokes, and after a few seconds catches and then you've got tons of power, more than with the old carb.

Here's whats been done to the truck engine wise in the last 5k miles:

-Intake 4bbl
-Q-jet
-Plugs
-Cap and rotor (HEI Distributor)
-New springs in the distributor
-Wires
-Vacuum advance
-In line filter (in addition to the one in the carb)

I would really appreciate some help. I just want the truck to run right! The entire time I have had it, it's never run right and I'm sick and tired of it.

Please help me!