Quadrajet Problem Solving > Diagnose a Quadrajet carburetor problem
Idle issues after rebuild
ducrider123:
I figured it out.
problem - When I looked down the vent when the engine was running I could see gas on the top of the gasket, as well as a little gas around the accelerator pump shaft. I figured I had the float to high causing the engine to flood. So I took the carb apart lowered the float a little. While I had it apart I pulled the idle tubes. Daunting but got them out. I then fallowed your recipe #2. reassembled it, and it runs great. I have full adjustment with the idle screws out 2.5 turns.
The difference from a Edelbrock 650avs to the Quadrajet is unbelievable. The power difference when the secondaries kick in is amazing.
I do have one question.
When I go from idle to WOT I have a hesitation. I had it with the Edelbrock also but a lot worse. If I don't hit it "hard" it pulls really hard no hesitation. I am assuming it is a momentary lean condition. Should I be looking to add a stiffer power piston spring, or tighten the secondary spring? It is at 3/4 turn. Also the secondary plates have notches in them.
Shark Racer:
--- Quote from: ducrider123 on November 13, 2012, 04:26:47 PM ---The difference from a Edelbrock 650avs to the Quadrajet is unbelievable. The power difference when the secondaries kick in is amazing.
--- End quote ---
You shouldn't feel the secondaries kick in... you may be able to hear it, but you shouldn't be able to feel it.
--- Quote from: ducrider123 on November 13, 2012, 04:26:47 PM ---I do have one question.
When I go from idle to WOT I have a hesitation. I had it with the Edelbrock also but a lot worse. If I don't hit it "hard" it pulls really hard no hesitation. I am assuming it is a momentary lean condition. Should I be looking to add a stiffer power piston spring, or tighten the secondary spring? It is at 3/4 turn. Also the secondary plates have notches in them.
--- End quote ---
3/4 turn should be pretty tight, but you may try going a little tighter. Is your choke pulloff hooked up and effective? (does it hold a vacuum?)
Do you really mean "idle to wot" or "cruise to wot" or...?
ducrider123:
Yeah, good point. I have my kickdown set so that when the secondaries open the trans kicksdown. Poor choice of words I guess. Correction: The power difference from the AVS to the Qjet is dramatically different.
The choke pull off does hold a vac and it is set at 1.5-2 sec release.
Maybe it is because I am use to 350 chevy's, and I have been able to go from idle to WOT without a bog. But ever since I have been working on my pontiac I have had a bog. The AVS was really bad. no matter what I did it stumbled really bad. (Dan at the tech center knows me quite well from all of my conversations with him.) The Qjet is a dramatic difference. If I just stand on it bogs for 1 sec then it recovers and launchs. If step into it transitions great. I know it's a lot to ask for a reaction from the carb but I was wondering if it could be improved.
Cliff Ruggles:
Even the slightest hesitation/stumble/bog going to full throttle indicates that there is either a momentary rich or lean condition. The Q-jet is easy to tune. I'd start with the accellerator pump and check ball, making sure there is a good seat at the check ball, and put a good pump in it.
The Edelbrock accl pumps are JUNK, as are most of the pumps from over the counter kits. The "blue" seal they use is soft and doesn't hold up or work well with this new fuel.
The springs they put on and under the pump are incorrect, and will cause the problems you are seeing.
The choke pull-off release time/rate, and secondary spring tension are also a player. There should be no play in the linkage going from the pull-off to the secondary airflap shaft.
The POE system is a player here as well.
In almost all cases, when we see carburetors that are causing problems when the driver goes quickly to full throttle, it's just a matter of minor adjustments and some better parts....Cliff
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