[alanmay0]

I have purchased a quadrajet carburetor for my 1967 GTO over a year ago. Just got around to putting it on. Having a hard time adjust the idle mixture screws. Seems that the carb is sucking in air around the shaft that comes though the carb body. This is the shaft that the two front butterfly's are attached too. When I spray carb cleaner at this location the engine wants to die.

Yes I have checked everything else including replacing the 3 gaskets, resurfacing the intake manifold, plugging the two holes where the exhaust gases run under the bottom of the carb. When I screw in both air/fuel mixture screws the car still runs.

Is this normal for air to leak at the shaft where it comes through the body of the carburetor??

Well be sending the carb back to the company I purchased it from for repair or replacement if this is not normal

thanks to all
alan

[equidr]

This is very common but not "normal". In a quality rebuild the baseplate should have bushings installed where the primary throttle shaft goes through. This will control the vacuum leak. You can do this yourself with a kit from Cliff. Sending the carb back to a place that did substandard work in the first place will probably not resolve your issues with the carb.

[max 93]

May I suggest using different titles for you threads. You have two threads withe the same title

[Bandit400]

This is a common issue, but it is not normal. It is caused by wear in the shaft bore, and can be corrected by removing the shaft, and drilling the bore. Bushings are then placed in the hole, and you are good to go. This is usually checked for and corrected during the rebuild. I hope this helps!

[steve25]

That's a common ware issue on used Carbs and it can be fixed by installing throttle shaft bushings .
If you have done full on Carb rebuilds you can get kits along with the needed drill bit to do the repair yourself, if not send it out to the fellow Cliff on this site.

[chiphead]

Any Q-jet that is sucking air past the throttle shafts is worn out at the throttle body. Time for a total rebuild and bushing job. Take it back off, you'll never get it to run right the way it is. Unmetered air going past the shaft makes the carb impossible to tune.

Generally, you never, ever buy a "mass remanufactured quadrajet". They are never, ever worth a damn. Maybe as a boat anchor. The rebuilders just tear them apart and slap them back together without any quality control. Even if the body isn't ruined by the rebuilding process, the generic tune isn't right and the car never really runs to maximum potential. You end up going back into it to correct the work that wasn't done and modify the primary system to work for your engine.

The specialty shops like Clifff or CarbKing do wonderful work, but you send them a core and tell them exactly what you want. You don't just get one off the shelf. Cliff literally wrote a book on them, and he sells all the parts required to do a top-notch carb yourself.

The shaft bushing job is time consuming and expensive part of a rebuild, but totally worth it. If this carb is supposed to be "rebuilt and ready to run" I would return it and get a refund. This is why I build my own carbs.

[Greg Reid]

Cliff actually has a bushing kit with the bit included.
https://cliffshighperformance.com/Qu...et-bushing-kit

chiphead is correct about the 'reconditioned' carbs. There was one included with my '68. It was totally butchered to get it to run on pretty much any q-jet equipped car but it would never run right. Some of the bypasses were filled with lead and that sort of thing. Sometimes they mix and match parts from a pile of carbs it seems.
I bought a decent core and rebuilt it with a Cliff kit, which included the bushings and drill bit.

[alanmay0]

Thank you. Who is Cliff and how can I contact him.

thanks alan

[Greg Reid]

That link I posted has a phone number and he is also an active forum member, going by CliffR, so you could pm him that way.

[chiphead]

To add to what Greg said, the Q-jet was constantly evolving and being improved for each application. The jetting, airbleeds and metering system was dialed in by the engineers for each car/engine/drivetrain application.

The mass rebuilders will typically take them all apart and mix-match the air horns, main bodies and throttle bodies between similar models. Then they will butcher the airbleeds and metering systems for a "generic" tune that will start and run on a SBC or a BBC. Bushing the throttle shafts, replacing air door springs and air door cam, using correct dashpots, etc typically isn't done.

This is why it's better to find a dirty, unmolested original and send it out for rebuilding at Cliff or CarbKing or buy the parts and DIY for your application. Some guys give up and go Holley, there's no shame in that if you want to drive the car and not play watchmaker with a bunch of carburetor bits and doo-dads. There is a downside in making the Holley fit the intake and tuning it for the application. There is no free lunch in this hobby.

[Squidward]

Another thumbs up for the Cliff bushing diy kit. It brought back tuneability, and made me feel like it was prom night all over again.

And this was on a tremendously worn $5 swap meet Qjet.

[alanmay0]

Well here might be a problem. This being a rebuilt qjet already it has had new bushings put in it. These are the bushings that are loose. So can these be drilled out and then new bushings reinstalled or what?????

thanks
alan

[ponchjoe]

Originally Posted by alanmay0

Thank you. Who is Cliff and how can I contact him.

thanks alan

https://cliffshighperformance.com

Call him in the mornings but be prepared to know what parts are in your carb. If not he can sell you everything you need. He is very knowledgble and helpful.
Shaker455 on here is knowledgeable as well.
Seam Murphy Induction (SMI) is on web and offers qjets.
There are others too, google is your friend.

["QUICK-SILVER"]

Originally Posted by alanmay0

Well here might be a problem. This being a rebuilt qjet already it has had new bushings put in it. These are the bushings that are loose. So can these be drilled out and then new bushings reinstalled or what?????

thanks
alan

Just cause it's rebuilt does not mean it got the throttle body drilled and repaired with bushings. They did not come factory with bushings.
Can you see a bushing from the outside or did you pull the carb off and look at it from the bottom?
If it does have bushings...need to see if the bushings are loose in the throttle plate or if the throttle shaft is loose in the bushing.

Sometimes you can change the direction of pull or angle of the throttle return spring to regain 'some' idle control. Depends on how loose the shaft is in the plate. Too loose and the throttle blades wont close in the same spot every time. Leaking above the shaft doesn't cause problems like leaking below the shaft does. With the factory return spring setup you usually get front to rear play instead of up and down play.

As mentioned, might be time for a different core and have it rebuilt right and calibrated for your engine.
Clay

[STEELCITYFIREBIRD]

The engine still running with the idle mixture screws closed means either your getting fuel from somewhere other than the idle circuit, or you have the throttle blades open so far your pulling off another circuit in the carb. Who knows where if parts were interbred.


Bushings loose in the throttle body sounds like total crapmansnship.
Big red flag.

[Schurkey]

Originally Posted by alanmay0

plugging the two holes where the exhaust gases run under the bottom of the carb.

BEFORE I did anything else, I'd make VERY sure that the gaskets seal any possible air leaks between carb throttle body and intake manifold gasket surface.

It would be very easy for there to be a giant sucking air leak in that area--especially if the OEM high-temperature gasket and steel heat shield weren't being used.





Yes, it's very suspicious that a giant air leak AND screwing the idle mixtures closed don't result in the engine stalling.

[alanmay0]

I have tapped and plugged the exhaust that passes under the carburetor, I have removed the manifold and taken it to a machine shop for resurfacing, I have replaced the three gaskets that you are referring too. Then I removed the carburetor and only used one gasket. I have plugged all the vacuum ports on the carburetor to be sure that vacuum was not leaking from anywhere else. Still when I spray carburetor cleaner where the butterfly shaft sticks out and connects to the throttle cable the engine almost dies. Can't think of anything else to check. Am sending it back for service.
thanks
alan

[Schurkey]

Originally Posted by alanmay0

I have replaced the three gaskets that you are referring too. Then I removed the carburetor and only used one gasket.

I don't know what "three gaskets" you're referring to. There should be ONE (high-temperature) gasket, and ONE heat shield.

If you're not using the correct gasket and the correct heat shield, there's a reasonable chance there's an air leak even with the exhaust channel plugged on each side.

[chiphead]

I forgot that the 67 manifold has that goofy heat passage under the carb itself. The carb to manifold gaskets required for that intake are different than later pontiac intakes. Even so, you should be able to tell the difference between that and a throttle shaft leak.

[Greg Reid]

Originally Posted by STEELCITYFIREBIRD

The engine still running with the idle mixture screws closed means either your getting fuel from somewhere other than the idle circuit, or you have the throttle blades open so far your pulling off another circuit in the carb. Who knows where if parts were interbred.

This is true also. Maybe because of the throttle shaft problem, you are idling the car up so far that you're opening the primary throttle blades and pulling fuel from the part-throttle circuit instead of the idle circuit.