Cliff's Quadrajet Parts and Rebuild Kits
Quadrajet Problem Solving => Diagnose a Quadrajet carburetor problem => Topic started by: BenNoakes on September 28, 2024, 07:07:05 PM
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Hi folks,
I have a 78 403 Olds with a rebuilt matching 17058253 with parts and specs from Cliff. It was running well a number of years ago, then the vehicle went into project stage of sitting around.
I'd occasionally kick it up and needed to adjust the choke for better start or idle as it was never perfect. As usual, somewhere along the way it got worse and I'd tried a few things, I adjusted nearly everything in and out just to record where they were at compared to my original notes and have a think.
The choke fast-idle cam was giving me some grief. In typical carb style I could get it back to starting nicely but stumbling as it warmed up, or hard to start, but then idling nicely once warm.
Then it sat some more, moved house, car is in storage and hasn't been accessible until now. I can't even recall where I was up to but now upon attempting to start it is popping and banging and hard to start like the timing is way off. I haven't touched the timing. I also don't want to at this point as something else has done it that I'm not aware of.
So basically, before I go stare at it again, is there a choke or adjustment setting that can affect timing? Obviously vacuum-advance is connected, hasn't been touched. The choke fast-idle is perhaps a little high but I didn't think it was high enough to pull the timing right out on cranking. And do you think I can find my notes of all the current settings, no chance!
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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.
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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.
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Seem to have got it sorted, mixture of running too lean and fast idle turned far too much.
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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.
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Sounds like you might need to go through the ignition.
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I'm with 77 ^ , It would be nice if you had a known good distributor to stab in the hole.
QJ
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Ignition is new and good. Turns out qjet started dumping fuel into the intake and fouling up the plugs instantly so I've now taken it off to see what's going on or if leaking. That will sure make a difference in trying to tune...hopefully.
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Did you rule out bad fuel here?
Looking at your posts it appears that the car has been sitting around for quite some time with little use.
This new fuel goes bad quickly.
Since you've narrowed it down to the carb at a minimum I'd pull it apart and clean it out, and see if anything found it's way into the N/S assembly causing it to flood....