General Category > Quadrajet Carb Talk and Tips
Dance steps, need some help!
Cadman-iac:
--- Quote from: 77cruiser on October 19, 2025, 05:39:55 PM ---I'd go back to .048 UIAB.
--- End quote ---
That's not as easy as it was to enlarge it. Not sure i have the resources to do this. Gotta look at my options.
Thanks for the suggestion.
Cadman-iac:
--- Quote from: Kenth on October 20, 2025, 12:33:33 AM ---IDCR are plenty large at .057", as are .040" idle tubes.
(I would look for .052" IDCR with .038" idle tubes with the .061" UIAB.)
Set APT by the "tip-in" method at 2200 rpm´s and let it be.
Set idle mixture screws one half to one turn further out and i guess you´ll be good for now.
JMHO
--- End quote ---
Kenth,
I tried .061 IDCR's but it didn't work, just seemed to raise the problem to a higher rpm.
I've got a lot of various sized restrictions, so going back to a smaller one is not a problem.
I've also got a lot of different idle tubes, so that's no problem.
I'll go back to those sizes and see what happens.
Thanks for your help.
Cadman-iac:
--- Quote from: novadude on October 20, 2025, 06:06:34 AM ---I think those caddy carbs have large lower idle air bleeds. I wonder what would happen if you reduce those a bit to ~0.062? This is just a "what if" question.... I can't say that this will fix your issue.
Seems to me that just off-idle, those holes (and the top of the transfer slot) would be adding air to the mixture coming from IDCR.
--- End quote ---
Yes, the lower idle air bleed on this one is at .078, and i haven't made any changes to those.
I was just wondering about going back to the original size on the bypass air passages, I have the means to do that.
I'm not sure where i saw that the small bypass passages were too small, I went through all of my posts and threads looking for it.
There are several suggestions to enlarge the discharge ports.
Would small bypass air passages be a fix?
I thought i was figuring things out, now I'm not so sure.
77cruiser:
A smaller IABP would help. Making the LIAB smaller would help too as Novadude mentioned. Some are successful at peening the holes then drill to size. I just drilled & tapped for 6-32 brass set screws.
novadude:
I've peened the lower idle air bleeds from ~.078 down to ~.06x before using an old accelerator pump check ball and a punch (and then qualified both with a drill to the same size). It's not the easiest thing to do, and the casting ended up looking ugly, but it's one way to address this. I don't have any before and after comparisons, as it was a new build and I was changing multiple things at once on this particular carb.
Setscrews as 77cruiser suggested would probably be a better idea. I wasn't sure if I could get a setscrew in there that was short enough so that it wasn't blocking the part of the down channel leading to transfer slots and idle discharge.
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