Porous Quadrajet
Thread Starter
Instructor
Joined: Jan 2007
Posts: 232
Likes: 41
From: Simpsonville SC
Porous Quadrajet
I have a spare Quadrajet that has a leak down problem. I have determined by multiple leak down test that the walls between the float bowl and the primaries must be porous and allowing fuel to ‘seep’ out into the primary venturis. The walls of the venturi were wet after the bowl had drained down to about a ¼ inch remaining in the bowl. I used some super sticky packing tape cut to cover the fuel bowl walls and repeated the leak down test. The fuel level never changed for days and no more wet venturi walls. Can this be repaired? I tried a thin application of Marine Tex but it didn’t stick. Has anyone used those gas tank sealers in a carb fuel bowl for this type of repair?
Melting Slicks
Joined: Mar 2006
Posts: 2,465
Likes: 0
From: Orange Park Fl
From what I have heard, this is a rare but fatal Q-jet problem. If the casting is indeed porous, it needs to be replaced. Any repair will be unsatisfactory. (Sorry, that's just what I've heard).
God bless, Sensei
God bless, Sensei
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
Interesting problem.Probably best to toss it.
But I wonder if you filled the bowl with lacquer thinner or acetone and let that soak through with the idea that would clean the porous area and let that dry and then filled the bowl with a real thin radiator sealer and let that soak through the porous area and let that dry if that would do it?I think trying to seal the surface is going to be tough.
But I wonder if you filled the bowl with lacquer thinner or acetone and let that soak through with the idea that would clean the porous area and let that dry and then filled the bowl with a real thin radiator sealer and let that soak through the porous area and let that dry if that would do it?I think trying to seal the surface is going to be tough.
Tech Contributor
Joined: Aug 1999
Posts: 14,377
Likes: 6,377
From: At my Bar drinking and wrenching in Lafayette Colorado
I have fixed porous Q-Jets (actually a pretty common problem) using a thin coating of JBWeld in the affected area. After lightly abrading with 220 grit sandpaper and cleaning with IPA, I have "coated" the porous area with JB. I haven't received any feedback from people if this repair has had a long useful life or not, but it will repair the issue at least temporarily.
Lars
Lars
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