How to Adjust Quadrajet Idle Mixture?
At rebuild time before putting the carburetor on the vehicle turn the screws all the way in gently. Turn the screws back out 2 or so turns.
One on the vehicle warm up the engine and set the idle to manufactures specification.
The choke valve should be all the way open and the idle screw sitting on the lowest point of the fast idle cam.
Start by turning the idle mixture screw out until the RPM drops.
Then turn each screw 1/4 turn and wait for the RPM to catch up.
When turning in 1/4 turn makes the RPM drop, turn the screw back out 1/4 of a turn.
You can make a final adjustment to get the engine to run smoothly.
How to Adjust Quadrajet Float?
Hold the float hinge in place.
Hold the float down at the hinge so that the needle is closed.
With the bowl gasket removed, measure from the top of the casting to the top of the float. The illustration indicates 3/16" but you should refer to the specification sheet. Not all Quadrajets are the same.
Adjust by bending the float hinge as show in the illustration. Do not put pressure on the needle. It will be damaged and carburetor flooding will occur.
