Quadrajet Problem Solving > Diagnose a Quadrajet carburetor problem
Won't idle anymore.....and seems to flood?
Cliff Ruggles:
Over tightening the long front bolts will "pull" the front corners of the airhorn down and warp the entire front of the airhorn and main casting.
It's really NOT a big deal as some other "experts" have eluded to. As long as both parts are warped at pretty much the same rate and they gasket gets compressed there will not be any problems.
I do see a few that are "humped" up enough between the long bolts and front center airhorn screw to seep, wick or leak some. This usually happens on the accl pump side. The fix for that 99 times out of 100 is to gently run the front of the airhorn across a belt sander to flatten it slightly more than the main casting.
At this point installing one of my kits with a .015" thicker (and better material) top gasket and gently pulling down the outer bolts to re-conform the top the middle section is a perfect fix.
To date I'm over 15,000 work orders since going full time and keeping records and in all those carbs I've effectively sealed all of them up in that fashion except about half a dozen where they were pulled down so hard the casting and airhorn were warped over 1/4" and the head of the bolts had just about chewed their way clear thru the top!!
Warping really isn't a big problem 99 times out of 100, and I've gotten so good at flattening airhorns it's about a 3 to 5 second operation then assembly begins.
Our SR rebuild kits for the early carbs automatically come with the .015" thicker main body to airhorn gaskets. I also put one in the HP kits in addition to the standard thickness.
IF you want a thicker gaskets I'll substitute it with any kit order at no additional cost, just ask when placing an order.
I will also substitute the HP accl pump assembly and larger fuel inlet seat as well if you need those items in your rebuild kit........Cliff
fussfeld:
Nope----still doing it. Baffled.
i am only getting 3lbs fuel pressure according to the new gauge. So i don't think that is the problem.
So, to recap:
1) All i did was bend this tab to get the secondary throttle plates to open; The secondary plates really did not open at all when i first got the carb. i got them to open to at least 70%.
(This is not the actual carb in question though.)
2) Did an "acceleration test."
3) Immediately after the "acceleration test," did the symptoms start: i can't keep it running below 900-800ish rpm if i take my foot off the pedal. After it stalls, very difficult, if not impossible to start, unless you wait 30mins. to an hour. Then, it starts. Starts cold ok.
Could moving that tab cause other problems? It must be something simple, but i'm baffled.
fussfeld:
P.S.
4) i DID NOT take the carb off the manifold when i bent that tab. You....are/aren't supposed to take the carb off when you do this....?
Cliff Ruggles:
Yes. ALL linkage adjustments should be made on the bench with the baseplate removed. Then you can tell for sure that the throttle plates are opening all the way up, and that they are fully seated when closed.
If they are hanging open any at all you will get a "flooding" condition as the high vacuum at idle will suck fuel directly from the secondary nozzles instead of the idle mixture screw holes.....
fussfeld:
i was hoping it WAS the secondaries hanging up----then it would be an easy diagnosis. But they appear to me to be sealing up normal: Here's a pic. i had a light underneath as well:
They looked to be sealing up normal when on the manifold as well.
IF the secondaries are closing normal, is there anything else that might cause fuel to discharge from the secondary nozzles?
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