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Re: Adjusting Idle Mixture Screws Does Nothin - Quadrajet
The motor needs to be fully warmed up before adjusting the idle mixture. Choke fully open. Idle between 600-700 rpm. Vacuum should read between 18-22 if things are close depending on if your distributor vacuum advance is on ported or manifold vacuum. Timing with no vacuum advance should be around 8-10 BTC to start with.
If vacuum is way low at idle, suspect a leak or poor timing.
Before starting, screw the mixture screws full in until they gently seat. Too hard and you can enlarge the hole in the carb. Note how many turns each is out. Then back them out 1 turn and start adjusting. One turn out should be too lean but this way, you only have one way to adjust. At some point around 1 and 1/2 to 2 turns out, the motor should speed up a bit. Further turning out won't yield more speed. Find the best idle and vacuum reading, then turn that screw in 1/4 of a turn. The motor will slow a bit. Repeat for the other side.
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