Cliff's Quadrajet Parts and Rebuild Kits
Quadrajet Problem Solving => Diagnose a Quadrajet carburetor problem => Topic started by: kirkp on August 11, 2018, 12:05:42 PM
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Car is a 83 Hurst Olds stock 307. Bought the car and it ran fine when I bought it other than it wouldn't idle very well. It sat in my garage for a few months before I had time to mess with it. I tried to turn the idle screw up a little and took the car for a ride and then it wouldn't accelerate. About 2000 rpm it would fall on its face no matter how hard or easy I pressed the gas. If I stayed in the pedal it would sometimes backfire. Seemed to me like it was running out of fuel. Thought I would start with some easy things and went with plugs, wires, distributor cap and rotor, plus changed out all the vacuum lines. Still exactly the same. Ordered a carb kit from Cliff and went through the carb. I have rebuilt other quadrajets but never a CCC. The idle mixture screws were way off of the starting point of 4.5 turns out. The right side was 2.5 turns out and the left side was 1/4 turn out. I reset those to the 4.5 turns out and the idle is nice now. The acceleration problem is still the same. Does anyone have some suggestions? I don't know where to go next.
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If the mechanical advance is rusted & sticking it might be the cause. Did you pull the cap & rotor to check it?
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Disconnect the plug to the M/C solenoid and see if things improve. If so the solenoid isn't functioning properly and causing lean condition......Cliff
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Cliff, I will try that. One thing I noticed while rebuilding the carb is the stop on the air horn for that M/C solenoid was threaded out quite a way. I looked at some videos of other people tearing down these carbs and theirs did not look that far out. I didn't move it because I didn't know what a starting point setting was for it. I moved it a little one way and then back and it turned really easy. I'm not sure if this could have moved when trailering the car home.
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Here is a picture of the stop.
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Ok, that's what the problem was. The rich stop was all the way down against the solenoid plunger. I made a tool out of a piece of 3/16" brake line to turn the screw out until it seated. Then I set it to 4/32" of travel. The tool I made by cutting a piece of 3/16" brake line with a tubing cutter then tapping the cut end gently over the screw. I made a short piece the same way to hold the screw in place. Only thing additional I did with the short piece was squeeze the upper part of the line with vice grips to flatten it just enough to fit tight in the hole. Then I gently tapped it in until it seated. Hopefully that will hold the screw from moving. My only question now is the lean stop. I have the travel set, but am I setting that off of a good lean stop setting. I set the lean stop setting to what it was when I took the carb apart. Obviously someone has been tinkering with this carb and I do not know if the lean stop is set correctly
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For sure that rich stop is WAY too low.
I usually set them at the max-rich position for initial testing. Seldom do you have to bring them down very far for the best final adjustment.......Cliff