Trying to take another stab at this and could us some input. My quadrajet has always been adjusted all the way out on the idle speed screw and still idles 900RPM. The choke is set right at about 1500 RPM when cold, timing is good, carb was rebuild 2 years ago and runs great. Anything I'm missing? Would like to be able to adjust RPM all the way down to 600-700.
bad gasket alignment on intake,,, throttle plates touching em 2 bbl throttle cable and hokey cable bracket not letting the carb idle down ... undo linkage and see if that changes idle bent linkage ,,, fast idle cam on passenger side has issues not dropping out of the way,,,,
and ... hmmmmmmmmmm
thats all I got 4 now .. another budweiser after that nascar finish ,,,, whew !!! I might think of somethin else
Also, was that photo taken with the car shut off? If the car is shut off, it would have that gap. When running it should be activated holding the idle to about 650 rpm.
The forward is an emergency backup. The rear is the stock spring.
I think I might have found the issue. I disconnected the throttle cable and the throttle bracket snapped forward about an 1/8" or close to that. That might get me enough to close the primaries more and slow that thing down to 400RPM if I want to, I know I need to be at 650. The throttle cable is 20 years old, but hasn't seen more than 3000 miles. Hmm, not sure if I ordered a 2bbl cable? Would they be that close? Well, I'll try to long gate the hole on the cable, or buy a new one. I'll report back in a couple of days. Thanks all, good brainstorming, lol.
I think I might have found the issue. I disconnected the throttle cable and the throttle bracket snapped forward about an 1/8" or close to that. That might get me enough to close the primaries more and slow that thing down to 400RPM if I want to, I know I need to be at 650. The throttle cable is 20 years old, but hasn't seen more than 3000 miles. Hmm, not sure if I ordered a 2bbl cable? Would they be that close? Well, I'll try to long gate the hole on the cable, or buy a new one. I'll report back in a couple of days. Thanks all, good brainstorming, lol.
I would agree...throttle cable. Do you have A/C?
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Yep, 2 1/2 turns out, set with vacuum gauge, correct F4 bracket and the primary throttle shaft has newer bushings in it, no play. I am pretty confident its the throttle cable itself, I might have gotten a 2bbl cable when I replaced it 20 years ago.
Well crap, - I had a brand new Ames 4bbl throttle cable laying around and after installing it I got the idle down to about 800RPM. I'll never be able to get it to 500 so I can get the solenoid set to idle at 650RPM. The search for clues continues. Bad thing is I'm checking my dizzy for mech advance and am sure I'll have to kick the timing up slightly after I'm done, which will bring the RPM higher again.
I just about had a runaway on first startup after 5 years of sitting...the secondary butterflies were not seated properly, actually stuck partially open, and as soon the mixture got close it fired and ran way past idle, thankfully still had my hand at the key and shut it off quickly. Maybe the secondaries aren't fully closed.
After making some more adjustments to carb and timing I got the idle down to 500rpm. I believe it was a combination of worn primary shaft on carb, timing optimization and accelerator cable. All good now.