Hi All. I have a 1971 Cutlass and just installed a completely rebuilt original quadrajet carb. In setting up the carb and then test-driving, I find that pressing the gas pedal halfway down kicks in the passing speed secondary jets properly and it accellerates, however, if I press the pedal all the way to the floor, the engine hesitates and sputters and all 4 barrels don;t seem to be working right.
I have new plugs, wires,rotor,cap and timing is set at 14 Degs BTDC.
Can anyone give me some help as to what is out of adjustment, I am thinking the mixture screws, but the guys who re-built the carb set them up on a machine and said I should not have to touch them.
Thanks in advance.
Joe

 

You might be runnning a little on the lean side, that's what happened with a brand new rebuild on my 72 4bbl too. Also your timing should be 12° BTDC IIRC. Do you have your TCS hooked up? It was only on 71/72 engines. Part of its function was to advance the timing as needed under heavy acceleration.

 

I'll take a stab at this:

Choke pull off not set up correctly, preventing secondary flaps from operating correctly.
or
Spring on end of secondary air flap shaft is worn or adjusted incorrectly (letting flaps open to fast or not fast enough)

Don't know who rebuilt your carb, but check to see that these areas were addressed during the rebuild.

d1

 

Thanks...Don;t mean to sound dumb, but what is TCS ??

 

Sounds like the secondary air valve spring is set too loose, and on full throttle they dump open with no smooth transition. Also, their is a nylon cam that mounts on the secondary air valve shaft, right in the middle. You have to remove the air valves and the shaft to change it, and it is not generally found on parts store rebuild kits. The cam controls the lifting of the secondary metering rods out of the secondary jets as the air valves open, that richens the mixture at WOT. Those cams can wear, or even wear out and totally screw up secondaries.

 

Transmission controlled spark.
Do a search for this or "TSC solenoid".
It is an emission contol device that switched the disty vac advance from none to ported to manifold depending on engine temp and transmission gear selection.
It is frequently bypassed (many times incorrectly) when it fails, as no repros are made of it. This happened on mine and disty was connected to manifold vac - works fine.