72 carb quit will 76 carb work
Thread Starter
Racer
Joined: Mar 2010
Posts: 378
Likes: 0
From: NW sub of chicago IL
72 carb quit will 76 carb work
The carb on my 72 #7042202 is blowing fuel out the top and down the sides. There is a lot of fuel pooling in the manifold when I pulled it so it looks like a stuck float. I am going to rebuild it.
My question is can I put a 76 carb #17056206 on it and disable the hot air choke just to get it running for a week or so. Do I have to have a manifold for a hot air choke? Can this even work? They have nearly identical vac lines and are virtually identical in every other aspect so are there any other problem I may have? This is temporary because I have to order the parts and I have to get to work Monday
My question is can I put a 76 carb #17056206 on it and disable the hot air choke just to get it running for a week or so. Do I have to have a manifold for a hot air choke? Can this even work? They have nearly identical vac lines and are virtually identical in every other aspect so are there any other problem I may have? This is temporary because I have to order the parts and I have to get to work Monday
Race Director
Joined: Apr 1999
Posts: 11,520
Likes: 13
From: CORVETTE 77 385 C.I. TEXAS
It should work/run fine assuming it is from a similar engine. You can get an idea of the jetting by pulling the secondary rods & posting the 2 letter id. & 1 letter hanger id. On top 1 screw in back in middle between sec. holds the hanger & sec. rods. The later choke may work on your manifold or possibly transfer the choke.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
It sounds like you don't have much experience with carbs. If you are going to work on Q-Jets, you should spend $15 on Cliff Ruggles' booklet on "How to Rebuild and Modify the Quadrajet Carburetor". Read it before you do any more work that damages the carb.
P.S. It's probably only a bad/stuck float or a bad/stuck needle valve that is causing the problem on the '72 carb. Lots easier to fix than converting a later-year carb over.
P.S. It's probably only a bad/stuck float or a bad/stuck needle valve that is causing the problem on the '72 carb. Lots easier to fix than converting a later-year carb over.
Le Mans Master
Joined: Mar 2008
Posts: 5,948
Likes: 72
From: Oxford MA-----You just lost the game!!!!
Here's a pretty good article on rebuilding a q-jet. Oh, and I just talked to Captain Hindsight, and he said you shouldn't have tried to remove the screws holding the throttle valves on, you can clean and rebuild the carb just fine without doing so.
Scott
Whoops! Forgot to add the link!
http://vetteprojects.com/kstyer/quadrajet.htm
Scott
Whoops! Forgot to add the link!
http://vetteprojects.com/kstyer/quadrajet.htm
Last edited by scottyp99; Nov 5, 2011 at 10:50 PM. Reason: Forgot to add the link
Thread Starter
Racer
Joined: Mar 2010
Posts: 378
Likes: 0
From: NW sub of chicago IL
god speed Captain Hindsight 
well half way through the rebuild and the carb swap. A few more vac line and we'll see if the 76 carb is any good.
Is there any reason to not use stainless screw to replace the broken brass ones on the base plate.
well half way through the rebuild and the carb swap. A few more vac line and we'll see if the 76 carb is any good.
Is there any reason to not use stainless screw to replace the broken brass ones on the base plate.
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Le Mans Master
Joined: Mar 2008
Posts: 5,948
Likes: 72
From: Oxford MA-----You just lost the game!!!!
Also, if you look at my last post, you'll see that I forgot to post the link, and had to edit it. Captain Hindsite was right there telling me that I should have remembered to include the link before I posted. What would we do without him?!?!?!?
Scott
Racer
Joined: Nov 2004
Posts: 485
Likes: 1
From: Oakville ON
I am not sure, but you would be using 2 different metals which may react with each other so you would never get them apart. Stainless tends to gall and stick.
The originals didn't corrode at all, they were staked and I have never heard of one falling ouy but you coould grind off the tip and remove them (as you did).
I don't know why you would ever need to remove them 'thou.
The originals didn't corrode at all, they were staked and I have never heard of one falling ouy but you coould grind off the tip and remove them (as you did).
I don't know why you would ever need to remove them 'thou.
Melting Slicks
Joined: Jul 2010
Posts: 2,503
Likes: 33
From: McGrady NC
St. Jude Donor '15-'16
The only reason to remove any of the butterfly plates would be if the shafts or baseplate were severely worn and required bushing to take out the play. Put the brass screws back in and then hold the throttle shut before tightening to make sure the plates are correctly aligned as you tighten them. Otherwise you'll have some really weird idle problems. Then use a small punch or similar and stake over the threaded end a little to lock it down. Captain Hindsight must have been helping another forum member as you were in the process of disassembling your carb. Too bad...it would have saved you some trouble.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
Stainless screws would be good from the standpoint of not corroding. But, stainless is brittle and isn't easy to bend/swedge, so staking them like the brass ones were is not a good option. But, I'm not sure Loctite is a good retention approach, either, because of the presence of fuel. That's why the brass ones were staked. I think you would do better to put a dab of epoxy on the threads when you install the screws. That will make a difficult time of it if you ever want to take the throttle plates off the next time...but it's better than tearing up an engine because the screws and throttle plates got ingested by it. 
Thread Starter
Racer
Joined: Mar 2010
Posts: 378
Likes: 0
From: NW sub of chicago IL
i am off to see the wizard!
on a serious note I pulled the throttle plate to see if brass bushing were installed and they were and one fell out. guess its been spinning in place. the secondaries look reamed or drilled for bushing but none are in place. not sure if its necessary? Never seen secondary bushing for sale.
kit comes in Wednesday and carb is cleaned and ready for it.
As for screws, couldn’t find brass so I got stainless then I thought about them falling out, then blue lock tight came to mind, then I thought about the gas and heat , then using nuts seemed good, then thoughts about air flow around nuts stopped me, then I just went nuts. This is the train wreak of my thought and why I am off to see the wizard for a new brain
on a serious note I pulled the throttle plate to see if brass bushing were installed and they were and one fell out. guess its been spinning in place. the secondaries look reamed or drilled for bushing but none are in place. not sure if its necessary? Never seen secondary bushing for sale.
kit comes in Wednesday and carb is cleaned and ready for it.
As for screws, couldn’t find brass so I got stainless then I thought about them falling out, then blue lock tight came to mind, then I thought about the gas and heat , then using nuts seemed good, then thoughts about air flow around nuts stopped me, then I just went nuts. This is the train wreak of my thought and why I am off to see the wizard for a new brain
Race Director
Joined: Mar 2006
Posts: 14,112
Likes: 28
From: Florida
With the ss screws protruding just a hair on the shaft (1/16"), you can take the end of a sharp pair of vicegrips and squeeze the end of the threads a bit to distort them. Doesn't take very much to prevent them from coming out.
Have done it many times.
Have done it many times.
Race Director
Joined: Mar 2006
Posts: 14,112
Likes: 28
From: Florida
Thread Starter
Racer
Joined: Mar 2010
Posts: 378
Likes: 0
From: NW sub of chicago IL
OK final post.
The car does run fine with the latter model carb after it was set up, although I already switched back to the original. Trouble was that I threw an old aluminum manifold on an forgot that the distributor rotates 1:2 and for a week was trouble shooting a car firing on the exhaust stroke with out realizing it.
Thank you every one for your help
The car does run fine with the latter model carb after it was set up, although I already switched back to the original. Trouble was that I threw an old aluminum manifold on an forgot that the distributor rotates 1:2 and for a week was trouble shooting a car firing on the exhaust stroke with out realizing it.
Thank you every one for your help