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31
Diagnose a Quadrajet carburetor problem / Re: Quadrajet choke affecting timing?
« Last post by BenNoakes on October 27, 2024, 12:47:14 AM »
spoke too soon, what a piece of crap. If it idles nicely, there's no way it will restart when cold. Then after several attempts you will need to remove and clean all the wet and sooty plugs. I haven't had it even fire up today, now I'm seeing the fast idle screw isn't even touching, and barely touches by the time the spring is bottomed out. Now have to clean the plugs all over.
32
Diagnose a Quadrajet carburetor problem / Re: fuel dribble through primary venturis
« Last post by johnt365 on October 26, 2024, 09:00:35 AM »
Thank you for all the ideas.  Turns out when I reinstalled the carb after an intake gasket repair, I did not check the throttle cable connection. It was about an 1/8 in too short and was causing too much transition slot to be exposed.

I adjusted the throttle cable properly and replaced the 10 yo nitro float and the idle was back and the mixture was much better.

A couple APT adjustments and car runs great again. 

Thanks again!
33
Diagnose a Quadrajet carburetor problem / Re: Quadrajet choke affecting timing?
« Last post by BenNoakes on October 21, 2024, 07:09:18 PM »
Seem to have got it sorted, mixture of running too lean and fast idle turned far too much.
34
Diagnose a Quadrajet carburetor problem / Re: Quadrajet choke affecting timing?
« Last post by BenNoakes on October 19, 2024, 03:57:57 AM »
Thanks. After playing around with choke settings and making things worse, that's the symptoms I have, as if timing far too advance, Hard starts, fast idle and back firing/popping. Timing hasn't been touched. I need to try and undo what I've done, of course, I don't know what I've done.
35
Diagnose a Quadrajet carburetor problem / Re: Stubborn Lean Idle Problem
« Last post by 71silverstar on October 16, 2024, 08:59:49 AM »
Left a message at the shop...
36
Diagnose a Quadrajet carburetor problem / Re: Electric Choke Issues?
« Last post by TravisUT on October 16, 2024, 06:13:51 AM »
Thanks Cliff. Do you have some pictures of those locations, to help me understand better?

Engine had a cylinder that was stuck with rust; had an engine shop strip it and rebuild it. Carb was disassembled, cleaned and rebuilt, using a kit from another seller.
37
Diagnose a Quadrajet carburetor problem / Re: Stubborn Lean Idle Problem
« Last post by 71silverstar on October 16, 2024, 03:47:16 AM »
Will do...Thanks Cliff and Kenth!
38
Diagnose a Quadrajet carburetor problem / Re: Electric Choke Issues?
« Last post by Cliff Ruggles on October 16, 2024, 03:41:20 AM »
Part of the electric choke "conversion" requires blocking off the vacuum supply BEFORE the housing.  This can be done under the plastic choke seal, inside the plastic choke seal, or in the passage in the housing just after the seal.

Otherwise you have not only a vacuum leak that sucks unfiltered air into engine, it pulls in cold air that can effect the operation of the electric choke.

You mentioned that the engine and carb were "rebuilt" 3 years ago?  What exactly was done to the engine?  Did you put one of my rebuild kits in the carburetor?

Running rich ever since this work indicates something isn't quite right someplace and may be contributing to your issues......
39
Diagnose a Quadrajet carburetor problem / Re: Stubborn Lean Idle Problem
« Last post by Cliff Ruggles on October 16, 2024, 03:32:57 AM »
.038" idle tubes would be plenty assuming stock engine with the original camshaft.

The 1971 455HO and 400 four speed carburetors are just too lean from the factory to work well on this new fuel. 

When you get time call me at the shop and I'll send a better jet/rod combo for it.  I've rebuilt and restored a lot of those and could never get one to pass testing with the stock tuning parts in it....
40
Diagnose a Quadrajet carburetor problem / Re: Stubborn Lean Idle Problem
« Last post by Kenth on October 16, 2024, 01:50:07 AM »
Before opening the idle tubes further i would take a hot cylinder compression test and verify the ignition system, running voltage to the coil, points dwell etc.

BTW, i have measured the idle tubes and downchannels in an unmolested 7041267 to .037" and .057" så i think you´re not to far off in that regard, but with todays fuels you may need .041" idle tubes.
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