1968 4mv quadrajet
Thread Starter
Racer
Joined: Feb 2006
Posts: 428
Likes: 1
From: West Des Moines Iowa
1968 4mv quadrajet
Do any of you have this problem that occurs with me quite often: This is concerning the filter nut (that takes a 1" box wrench to remove) that holds the bronze filter in the fuel inlet. I have replaced the red fiber filter nut gasket 3 times now during the past few years, but I still get a little fuel leak coming from the filter nut area. This leak does not happen all of the time. Sometimes I can drive all day and not have a drop. Other times, I can start the engine up and check under the hood while idling and find a few drips every minute or so come out around the filter nut area. It is not the plug on the end of the fuel inlet, but definitely coming from around the large filter nut. Their are no cracks around the fuel inlet area, since some days I can drive it with no leakage at all. I can tell you this, that it doesnt do it right after replacing the gasket in the filter nut, it happens the week after or so. Someone told me that their is a trick on screwing both the fuel line (5/8 inch) and the 1 inch filter nut in correctly so they dont work themselves out again. Can anyone enlighten me on this trick??? Thanks guys 
Gonzo
Gonzo
Team Owner
Joined: Jun 2000
Posts: 38,923
Likes: 1,481
From: Southbound
Cruise-In II Veteran
No leaks on my '68. I'm not sure there is a "trick" to this, but I always hold the carb fitting (the big one) with a wrench while tightening the fuel line fitting to it.
Team Owner
Joined: Jul 1999
Posts: 26,545
Likes: 46
From: Huntersville NC
nothing comes to mind, other than it is very easy to strip the threads in the fuel inlet if you overtighten. Also you need a nice finished end on the fuel line so it won't leak. Not sure why it would be ok with a new gasket but start leaking a few days later.
Le Mans Master
Joined: Mar 2002
Posts: 6,217
Likes: 1
From: End of the Ike IL
Cruise-In V Veteran
Cruise-In VI Veteran
I went to a local carb shop and got some of the plastic/nylon gaskets. I think they were like three for a dollar. Mine is leak-free. You don't over-tighten those or they will leak, too. That's one reason I only have one spare left. 
Thread Starter
Racer
Joined: Feb 2006
Posts: 428
Likes: 1
From: West Des Moines Iowa
thanks for the tips guys, but I was looking for something else. I dont have any permanent leaks, it just happens off and on. I need to know how to permanently tighten the filter nut so it doesnt come loose again. 
Gonzo
Gonzo
Thread Starter
Racer
Joined: Feb 2006
Posts: 428
Likes: 1
From: West Des Moines Iowa
thanks Glenkov and Sensei, I will try the method of holding the large nut when tightening the smaller one. I dont know about the teflon idea, will that hurt the carb if particles of the teflon get into it???
Gonzo
Gonzo
Last edited by gonzo14; Jun 20, 2006 at 08:43 AM.
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Tech Contributor
Joined: Aug 1999
Posts: 14,375
Likes: 6,374
From: At my Bar drinking and wrenching in Lafayette Colorado
Since the nut does not seal on the threads (it's not pipe thread...), the Teflon tape actually has no sealing effect at all. Rather, what the Teflon is doing is acting as a thread lube to allow proper torque of the nut. Instead of using Teflon tape (which can cause particulate generation and contaimination of the carb), I recommend coating the threads on both the big carb inlet nut and the trhreads on the fuel line nut with white lithium assembly grease. This will allow you to get good tightening of the hardware without galling or damaging the threads, thus assuring a leak-free joint.
Safety Car
Joined: Dec 2004
Posts: 4,071
Likes: 0
From: San Diego CA
Originally Posted by gonzo14
thanks Lars, will try that idea...Hope it works!!! Hmmmmmm, white lithium assembly grease....hmmmmmmm, isnt that the same stuff you use on the power window tracks??
Gonzo
Gonzo
That's the goop you put on your ball joints to keep em from squeeking.
Thread Starter
Racer
Joined: Feb 2006
Posts: 428
Likes: 1
From: West Des Moines Iowa
Well folks, I found out the worst yesterday, and I need everyones opinion on this again. Here's what happened: I tried to tighten the larger filter nut on the fuel inlet and it kept turning (everyones worst nightmare). I guess this means that the fuel inlet (which is made of pot metal) is stripped, since the filter nut is made of good quality steel. SO, now what do I have to do??? Buy a new carb completely, or do what a friend suggested and buy some kind of kit to repair the fuel inlet (I think a little larger filter nut that would go into the inlet, and it doesnt always work)...thanks for all of your help! 
Gonzo
Gonzo
Tech Contributor
Joined: Aug 1999
Posts: 14,375
Likes: 6,374
From: At my Bar drinking and wrenching in Lafayette Colorado
e-mail me for my Services Info Sheet. I can correctly repair the inlet with new stainless steel threads. Do not use the commercially available "inlet thread repair" nuts or kits - they will destroy the carb casting.
Lars
V8FastCars@msn.com
Lars
V8FastCars@msn.com
Thread Starter
Racer
Joined: Feb 2006
Posts: 428
Likes: 1
From: West Des Moines Iowa
Originally Posted by Kalway
Funny, after I read this thread I decided to check my fuel inlet this morning. Now I have a leak! 
It's just a few drips. I'll seal it this week.
It's just a few drips. I'll seal it this week.Gonzo
