The Ford Barn

B0B · 10-31-2010, 03:56 PM

looking for a pesky slow fuel leak in the carburetor on my 29 Model A and trying different things and taking it apart and testing it many times I checked the float valve, jets , float level setting several times well Today I finally found it !

The problem was a very slow leak at the base of the GAV adjustment where it screws into the Carb.I could see a tiny trickle of fuel from the base of the GAV brass fitting where it screws into the carb and it was running down under the carb . The GAV adjustment assembly was screwed in there very tight and I tightened it some more BUT it still leaked ( I was lucky could have broken it by over tightening ) ...Anyway I finally took it out and put a VERY TINY amount of the old fashioned "Mitee" Pipe thread dope on the threads then screwed it back in and tightened it firmly but not real tight like it was ...Anyway that stopped the pesky leak I had been bothered with for months now I suppose a teeny bit of permatex or ultra copper or whatever would have worked too ...Anyway So I thought I would pass this on so someone else may not have to do all that work to find this nasty little GAV leak like I did ... Keep Em Rollin ! B0B

Gary WA · 10-31-2010, 04:52 PM

Thanks for the follow up. Happy H"A"lloween!!! www.whidbeymodelaclub.com

pat in Santa Cruz · 10-31-2010, 05:06 PM

Thanks for the tip.

Once upon a time Permatex #2 was just the thing for something like this. But, Permatex #2 is alcohol soluble, and with ethanol, it just washes away. Teflon pipe sealant seems to hold up better. Permatex makes a product called moto-seal that is ethanol resistant, but thin, so I suspect pipe dope is just the right thing.

Tom Endy · 10-31-2010, 06:24 PM

The GAV mounting is a common place for a fuel leak in a Zenith. It sits below the fuel level in the bowl. The threads are a 1\8-27 pipe thread and are supposed to seal off when tightened. Quite often someone will have chased the threads with a 3\8-24 standard tap and it will not seal off. Sometimes chasing them with a 1\8-27 pipe tap will correct the problem if the 3\8-24 was not run too deep. I have sealed several off with the teflon pipe dope.

Tom Endy

B0B · 10-31-2010, 11:05 PM

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Thanks Guys for the replies and good suggestions ...I just checked the carb again I let it sit most of the day with the gas on and still no leak ...

B0b

10-31-2010, 03:56 PM	#1
B0B Member Join Date: Jun 2010 Posts: 82	Carburetor leak cured ! looking for a pesky slow fuel leak in the carburetor on my 29 Model A and trying different things and taking it apart and testing it many times I checked the float valve, jets , float level setting several times well Today I finally found it ! The problem was a very slow leak at the base of the GAV adjustment where it screws into the Carb.I could see a tiny trickle of fuel from the base of the GAV brass fitting where it screws into the carb and it was running down under the carb . The GAV adjustment assembly was screwed in there very tight and I tightened it some more BUT it still leaked ( I was lucky could have broken it by over tightening ) ...Anyway I finally took it out and put a VERY TINY amount of the old fashioned "Mitee" Pipe thread dope on the threads then screwed it back in and tightened it firmly but not real tight like it was ...Anyway that stopped the pesky leak I had been bothered with for months now I suppose a teeny bit of permatex or ultra copper or whatever would have worked too ...Anyway So I thought I would pass this on so someone else may not have to do all that work to find this nasty little GAV leak like I did ... Keep Em Rollin ! B0B

10-31-2010, 05:06 PM	#3
pat in Santa Cruz Senior Member Join Date: May 2010 Location: santa cruz, calif Posts: 2,011	Re: Carburetor leak cured ! Thanks for the tip. Once upon a time Permatex #2 was just the thing for something like this. But, Permatex #2 is alcohol soluble, and with ethanol, it just washes away. Teflon pipe sealant seems to hold up better. Permatex makes a product called moto-seal that is ethanol resistant, but thin, so I suspect pipe dope is just the right thing.

10-31-2010, 06:24 PM	#4
Tom Endy Senior Member Join Date: May 2010 Location: Southern California Posts: 3,131	Re: Carburetor leak cured ! The GAV mounting is a common place for a fuel leak in a Zenith. It sits below the fuel level in the bowl. The threads are a 1\8-27 pipe thread and are supposed to seal off when tightened. Quite often someone will have chased the threads with a 3\8-24 standard tap and it will not seal off. Sometimes chasing them with a 1\8-27 pipe tap will correct the problem if the 3\8-24 was not run too deep. I have sealed several off with the teflon pipe dope. Tom Endy

10-31-2010, 11:05 PM	#5
B0B Member Join Date: Jun 2010 Posts: 82	Re: Carburetor leak cured ! Sponsored Links (Register now to hide all advertisements) Thanks Guys for the replies and good suggestions ...I just checked the carb again I let it sit most of the day with the gas on and still no leak ... B0b

10-31-2010, 04:52 PM	#2
Gary WA Senior Member Join Date: May 2010 Location: Clinton,WA/Whidbey Island Posts: 4,104	Re: Carburetor leak cured ! Thanks for the follow up. Happy H"A"lloween!!! www.whidbeymodelaclub.com