Gas Leak

F

fiftychev

Junior Member
I have a Marvel Carb on a 30 Model A. It leaks where the GAV rod goes into the carb. I took the gas line off the carb and it continued to leak for a while.

The disconnected gas line leaks a couple of drops an hour so I guess the shut off valve isn't totally shutting off the gas.

What might be the problem with the carb?

Is the slight internal leak of the shut off valve a problem?
 
There is a valve that the float operates. This should shut off the gas getting into the carb regardless of the condition of the valve in the car.

The valve in the car does need attention. Could be as simple as lapping the brass surfaces.
 
If understood correctly, the leak is coming from the GAV ? I had the same problem.There is a rubber (or leather?) washer near the GAV brass tip you may want to check if seated properly. Also, I added a thin washer and tiny amount of teflon sealant where the outer portion screws in to the carb body . That stopped that leak. A leak from the air horn was coming from the float valve. Placed a dressed brass needle in which helped. As added insurance, add a modern small 1/8" ball valve available from most hardware stores to the gas line. There is a great thread on this site for Marvel rebuild but can't place the author.
 
I just replaced the under tank valve in my 1930 model because even with it shut off, it allowed enough fuel to pass through it to fill the carburetor and even though there was no drip from the carburetor (new Tillitson) there were lots of gas fumes coming from it. New under tank valve fixed the problem.

@ fiftychev: So you have a 1950 Chevy? I have a 1950 Plymouth.
 
Thanks rip94611. I have taken what I would call the needle part of the GAV out of the carb. ITs very tapered and looks pretty good . Is the rubber or leather seal in the seat part?
 
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