5.7/Quadrajet
 

MY smallblock/alpha Quadrajet seems to have statred idling rich, very much at cold start, then rich enough to stall when fully warmed up, and idled for five minutes or so after a hard run. It will then stall when shifing( shift interrupter seems to be fine BTW , like it is flooded, then it is hard to restart, nedeing full throttle and a lot of cranking to clear the engine. Once it is restarted , and revved a few times it shifts just fine without stalling and you can idle around for a while with no ill effects. Clould this just be a mixture screw issue? carb is a 1990, and never been rebuilt.. up until this season it ran just fine, so I wonder what changed? maybe I should just throw a rebuild at it. Anyone know how to lean a q-jet?

David

They like to sink floats. Look down the throat at idle and see if you see fuel dribbling from the vents. If so, you need a rebuild and a new float.

Quadrajets are also known to develop leaks around the lead plugs underneath the main body.If you rebuild use some 2part epoxy to seal all of the plugs

1. make sure your choke is opening correctly.

2. How's your fuel pressure? New fuel pump recently? Q-jets suffer a narrow pressure range of 5-7 pounds.

3. The power piston that moves the primary rods can stick up or down. If it sticks up, it'll over rich at idle and off-idle.

4. Could be saturated float as previoulsy mentioned.

5. Could be leaky well plugs as previoulsy mentioned.

Q-jets are easy to rebuild. Get a Sierra kit , a couple of cans of carb cleaner and a couple of beers and go to it. If the accelerator pump that comes in your kit looks different than the one in your carb, throw the kit pump away and get an Edelbrock #1982 Q-jet pump (its the original Hi-perf/marine accelerator pump).