Need help with Quadrajet problem
Thread Starter
Instructor
Joined: May 2005
Posts: 184
Likes: 13
Need help with Quadrajet problem
Hello. My car is a 1974 that I put a 396 into. It has a Quadrajet 4MV (i think). Today it was running very strange, the secondaries would not open. When I got back and took a look at the carb I noticed that the item I am pointing to in the picture below had slid out of the bracket, the hose to the carb had fallen off, as did the attached rods and levers. I put everything back together and took it for another drive but every time I hit a bump that white round vacuum pod slips right out of the bracket again.
Please take a look at the photo. I think I have this back together correctly however the vacuum pod is still slipping out of its bracket. So I have two problems. One is that it won't stay in the bracket it slides into, and the secondaries wont open a full throttle. Like I said I'm really weak on carbs so please keep it simple if you can. I'm getting ready to do an intake manifold swap but I don't want begin until I have this running correctly again. Thanks in advance for any help.
Please take a look at the photo. I think I have this back together correctly however the vacuum pod is still slipping out of its bracket. So I have two problems. One is that it won't stay in the bracket it slides into, and the secondaries wont open a full throttle. Like I said I'm really weak on carbs so please keep it simple if you can. I'm getting ready to do an intake manifold swap but I don't want begin until I have this running correctly again. Thanks in advance for any help.
Drifting
Joined: Dec 2004
Posts: 1,714
Likes: 42
From: Austin Texas
Here is my theory. when the vacuum secondary can there gets a vacuum signal, it pulls that rod toward the front of the car and holds the secondaries shut. This is so they dont flop open at low speeds.
My theory is that when the can fell out of the retainer and was just hanging there, the weight of it hanging was holding the secondaries shut. Hence no secondaries while driving.
I would not hesitate to McGuyver that. First I would try to wrap some teflon tape around the vacuum can so that it would fit tighter. If that didnt hold I would get some type of glue. Probably trim adhesive or something that is safe on plastic.
My guess is if you get it to stay put, and it functions, your secondaries will work. If you are prepared to replace it, whats the harm in trying some superglue first? Worst thing is you could lose secondaries again.
My theory is that when the can fell out of the retainer and was just hanging there, the weight of it hanging was holding the secondaries shut. Hence no secondaries while driving.
I would not hesitate to McGuyver that. First I would try to wrap some teflon tape around the vacuum can so that it would fit tighter. If that didnt hold I would get some type of glue. Probably trim adhesive or something that is safe on plastic.
My guess is if you get it to stay put, and it functions, your secondaries will work. If you are prepared to replace it, whats the harm in trying some superglue first? Worst thing is you could lose secondaries again.
Racer
Joined: Apr 2011
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Tech Contributor
Joined: Aug 1999
Posts: 14,380
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From: At my Bar drinking and wrenching in Lafayette Colorado
The little "tangs" that hold and squeeze the choke pulloff in place are broken off, allowing the pulloff to fall out of the bracket. You can remove the pulloff from the bracket and take some vice grips to "squeeze" the bracket tighter - this will allow the pulloff to be pushed into the bracket with a press fit, and it won't fall out. Barring that, you can JB Weld it into the bracket or run a piece of safety wire around it to hold it in. Or, find a junk carb with a good bracket and replace the bracket.
Lars
The secondary lockout is fine. No, NAPA does not carry Q-Jet Secondary Lockout levers. If it were needed (which it's not), most of us with used carbs sell the lockouts for about $10.
Lars
Lars
The secondary lockout is fine. No, NAPA does not carry Q-Jet Secondary Lockout levers. If it were needed (which it's not), most of us with used carbs sell the lockouts for about $10.
Lars
Team Owner
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From: Southern Cal Ca
St. Jude Donor '22
napa could have got me one for 30 bucks.
here
http://www.carburetion.com/sitesearc...%20PullOffs%20
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Verdad Gallardo
Team Owner
Joined: Aug 1999
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From: Ontario
This pic shows the tabs referred to by Lars. This is a #7044206 1974 Q-Jet (L-48, Automatic) manufactured by Carter for GM. It seems to be a different configuration than the OP's version. But being a Q-Jet neophyte I do not know why.
Tech Contributor
Joined: Aug 1999
Posts: 14,380
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From: At my Bar drinking and wrenching in Lafayette Colorado
Paul -
Good photo. Your carb is an actual '74 carb. The OP, although his car is a '74, has a '71 - '72-ish carb, which uses a different pulloff and a slotted secondary airvalve lever.
I like the heat shield!
Lars
Good photo. Your carb is an actual '74 carb. The OP, although his car is a '74, has a '71 - '72-ish carb, which uses a different pulloff and a slotted secondary airvalve lever.
I like the heat shield!
Lars
Team Owner
Joined: Aug 1999
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From: Ontario
Team Owner
Joined: Jan 2007
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From: Southern Cal Ca
St. Jude Donor '22
never said I did.
Does the pull off lock out the secondaries?
Where did I post anything about the lever?
I admit to misnaming the picture.
Since you have a resell, sell me a pulloff for an 81 for ten bucks?
tell me how 3 years ago when I needed a PO that Napa did not quote me high 20's and tax made it 30 bucks. so I am a liar?
tell me why NOW it is 20 bucks plus tax.
laugh all you want. you are the one ASSUMING things.
so when do I get the 81 pulloff for 10 bucks?
Team Owner
Joined: Aug 1999
Posts: 30,995
Likes: 99
From: Ontario
I don't have a 74.
never said I did.
Does the pull off lock out the secondaries?
Where did I post anything about the lever?
I admit to misnaming the picture.
Since you have a resell, sell me a pulloff for an 81 for ten bucks?
tell me how 3 years ago when I needed a PO that Napa did not quote me high 20's and tax made it 30 bucks. so I am a liar?
tell me why NOW it is 20 bucks plus tax.
laugh all you want. you are the one ASSUMING things.
so when do I get the 81 pulloff for 10 bucks?
never said I did.
Does the pull off lock out the secondaries?
Where did I post anything about the lever?
I admit to misnaming the picture.
Since you have a resell, sell me a pulloff for an 81 for ten bucks?
tell me how 3 years ago when I needed a PO that Napa did not quote me high 20's and tax made it 30 bucks. so I am a liar?
tell me why NOW it is 20 bucks plus tax.
laugh all you want. you are the one ASSUMING things.
so when do I get the 81 pulloff for 10 bucks?
Race Director
Joined: Jan 2000
Posts: 12,399
Likes: 247
From: San Jose CA
What makes your post MORE confusing is that the lever floating just underneath the choke, and above the secondary throttle blade pin, is a secondary lock-out.
The secondary lock-out lever is very visible in Paul's photo, riding on the pin in the secondary throttle shaft.
Last edited by Shark Racer; Apr 9, 2013 at 07:46 PM.
Team Owner
Joined: Jan 2007
Posts: 53,648
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From: Southern Cal Ca
St. Jude Donor '22
He as much called me a liar about a 30 dollar part.
other than misnaming the pulloff, my original post was good.
Available at napa and my experience was an expensive price.
Team Owner
Joined: Aug 1999
Posts: 30,995
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From: Ontario
Just fix and drive/enjoy your Corvette as I do. I hope you get things fixed soon.
Team Owner
Joined: Jan 2007
Posts: 53,648
Likes: 878
From: Southern Cal Ca
St. Jude Donor '22
I will like having a spare for 10 bucks.
I took my original apart and fixed the leak in the diaphram.
still working good.
don't know how long though.
so anytime someone will beat the going rate, I will buy.