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71
Diagnose a Quadrajet carburetor problem / Re: Electric Choke Issues?
« Last post by TravisUT on October 09, 2024, 05:36:05 PM »
Ok...I think it's all adjusted now. Got the choke and pull off's set, and it seems to be running good. Didn't spit any wet black spatter, so that's a step in the right direction. Once it was running, I hooked a vacuum gauge up to the big manifold port on the front-bottom of the carb, and adjusted the idle mixture screws to vacuum. Both are set about 3 turns out, and I'm getting 18 inches of vacuum. Is that good/ok?

I'm still getting a bit of smoke, but only on revving; idle and drive is ok with no smoke. I pulled a plug and it was all black. I just replaced those plugs a couple of weeks ago, but I suspect the out-of-tune was causing issues, yes? I don't want to replace them until we're confident the underlying cause is fixed...thoughts?
72
Diagnose a Quadrajet carburetor problem / Re: Quadrajet choke affecting timing?
« Last post by Kenth on October 09, 2024, 12:46:54 AM »
To answer your question, no, there is no way choke settings affect ignition timing.
However, incorrect timing settings or a malfunctional ignition system WILL affect the carburetor function.
73
Diagnose a Quadrajet carburetor problem / Re: Electric Choke Issues?
« Last post by Kenth on October 09, 2024, 12:20:57 AM »
This may help some.
Measurement is usually around .160"-.180" at upper/rear end of choke blade for M4 Qjets.
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Diagnose a Quadrajet carburetor problem / Re: Electric Choke Issues?
« Last post by quadrajam on October 08, 2024, 08:14:10 PM »
I should have been more clearer, you will fully retract the pull-off which should slightly crack the choke blade open then push lightly on the CHOKE BLADE for the 1/4 in. gap betwix the top of the choke blade and the air horn. adjust with the phillips screw on the pull-off.
You can do this with mouth vacuum and a piece of hose. doesnt take much.
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Diagnose a Quadrajet carburetor problem / Re: Electric Choke Issues?
« Last post by TravisUT on October 08, 2024, 05:57:04 PM »
I was waiting for a hand vacuum pump from Amazon, and of course the 2-day shipping turned into 3-day, so it won’t be here until tomorrow.  >:(

If I understand correctly, when applying the vacuum to the pull of, I want it to just crack open; and when pushing the pull off linkage all the way in, the full gap should be 1/4”…right?
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Diagnose a Quadrajet carburetor problem / Re: Electric Choke Issues?
« Last post by quadrajam on October 08, 2024, 05:33:24 PM »
I assume the pull-offs tested good....?
Prop the throttle open a little bit so it doesnt interfere, Rotate the choke cover back and forth
to make sure theres no binding,turn it til it just closes and tighten it down. Apply vacuum
to the front pull-off and it should barely crack open. Note that you can push it a little
more open with your finger due to the normal slop in the link. This is where you want the 1/4 inch
 gap mentioned before. there is a spring loaded phillips screw on the pull-off to adjust this.
When you  crank it up you will have to work quickly back and forth with the speed screws
and it will take several cold start cycles to get it dialed in.

QJ
77
Diagnose a Quadrajet carburetor problem / Re: Electric Choke Issues?
« Last post by TravisUT on October 08, 2024, 08:25:21 AM »
I just changed out the coil/cover, and did away with the hot air tubing. I still have them though. I will be checking the pull-off's today! In regards to tuning/adjustments: what is the best order to make the adjustments? Should I do the fast idle, primary pull off, secondary pull off, and then choke adjustment, in that order? Or a different order? I'm worried that one adjustment will mess up the other...
78
Quadrajet Carb Talk and Tips / Re: My favorite Quadrajet rebuilding tools:
« Last post by ramiroelliot on October 07, 2024, 08:05:14 PM »
Quote from: Pav8427 on September 20, 2024, 06:32:37 AM
Trying to respond with a photo from Iphone. Jpeg not allowed. Whats my work around options?

Thanks. Doug
You can post via 3rd party image sites (eg: https://postimg.cc)
79
Diagnose a Quadrajet carburetor problem / Re: Electric Choke Issues?
« Last post by quadrajam on October 07, 2024, 06:41:48 PM »
Some items to consider...  The hot air choke had some built-in idle air bypass by design.
You may not have that going on now with the electric choke. Did you change the choke housing
or just the bimetalic coil/cover? Do away with the hot air tubing?
Make sure the loop in the bimetalic coil engages properly with the peg inside the choke housing.
Crack open the throttle and make sure you can twist the black cover and move the choke both directions. Dont reuse the housing gasket and source the choke power from key-on.

That carb should have a rear and front pull-off. The front pull-off also controls the secondary
air valve. Never been a fan of any of the rear pull-offs.I would remove it for now and just
use the front pull-off. Make sure it cracks the choke about a 1/4 inch as 77 mentioned.

QJ
80
Dialing in your rebuilt Quadrajet carburetor / Re: fuel mileage with 750 quadrajet
« Last post by lightning boy on October 07, 2024, 12:54:43 PM »
Don't ever buy a carb with a rebuild tag on it.
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