Quadrajet Problem Solving > Dialing in your rebuilt Quadrajet carburetor
Freshly rebuilt quadrajet flooding from top of carb
Cliff Ruggles:
That small cam in a 350 engine should produce good vacuum at idle and not need a lot of idle fuel from the carburetor. The specs listed look fine, if it doesn't work well it has a fundamental issue someplace.
I see this sort of thing quite a bit, as about 1/3rd of what we do here these days is working on carburetors that have just been rebuilt but don't work correctly......Cliff
gregcarter:
You're right, it has plenty of vacuum.
I removed the carb, made a plate with an air chuck to seal the top of the manifold.
I put about 20 psi in there and couldn't hear any leaks around the manifold with my stethoscope.
I made a smoker and dumped smoke into the manifold until a little drift came out a open valve cover.
I don't think its leaking anywhere.
The last time I had it running, I sealed off every hose fitting (vacuum source) from the carb, ran it at idle, it was very rough.
I closed the choke to get it to smooth out. Then I opened and closed the mixture screws while watching the a/f meter to see if the mixture screws were functioning. Well, they were, just fine as long as the airflow was reduced.
I'm going to open the carb up again, and see if there is any restriction anywhere in the idle system, and if not, I'm going to open up the idle tubes to .037, and the mixture holes to .085.
It baffles me how this carb worked for years on three different engines, but doesn't today. Something has changed. I want to believe it is something outside the carb, but I can't.
If you think I shouldn't do the above change, or have a better specification, please post me.
Thank you for your help,
G. Carter
Cliff Ruggles:
If it's lean at idle open up the idle tubes and the DCR's, that will put more fuel to the idle mixture screws.
An external APT screw would be a good idea as well, with a spring on it to hold it's setting.
You mentioned installing bushings, did you use our kit to do this?
Did you ever get one of our rebuild kits for the carb?.....Cliff
MRSOFTE:
--- Quote from: Tarrcamp92 on April 09, 2015, 10:55:03 PM ---Hi there. I'm pretty new at the carb stuff, so I just recently got my carb rebuilt put it on fired the car up started no problem but as soon as the car starts to run fuel starts spraying from the top of the carb and the car stalls, from what I've been reading I'm guessing the float is being the problem? Just wondering if anyone knows why it's doing that and what can I do to fix it? Thanks
--- End quote ---
Do you have a brass float? And if so did you drop it? If you answer yes too both questions I bet it cracked.
Just ask me how I know...ha! ;)
Cliff Ruggles:
NEVER use a brass float in a q-jet. The failure rate for all current production brass floats we've used (or attempted to use) here has been 100 percent.
The latest production closed cell nitrophyl floats are excellent, zero failures to date with any of them, and they have better fuel control than the brass ones.......Cliff
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