Ford Model B Carb Question

Ken/SC

Ken/SC

Member
I have been running a model B carb on my A since I got it in 2007.
I have rebuilt it several times, but it has a chronic problem I have always just lived with. After turning the car and gas valve off, the carb starts to
drip.

I have tested the gas valve, it is fine. It does not leak. I tried the gross jet float valve the vendors sell for the B carb, I had other problems with it. So I put an original type float valve back on it and it works fine, but if I shut the car off and leave it for anytime I have to run it dry. This gets to be a pain.

I have set the gas level with a jar etc. Its just the float valve leaks from what's left in the line until it causes the gas to flow over the jet tops and it drips slowly out the carb throat.

Doe anybody sell a original type model be float valve with a Viton tip on it?
 
Ken/SC: It could be either one of two things happening. From your post, you feel it's the float needle valve. I would suggest that you remove the needle valve and seat. Then, with the very very lightest of blows, tap the top of the needle against the seat to try and create a better seal. If that doesn't fix your problem, I would lower the float level 1/8 inch. What may be happening is the cooler gas is expanding in the carburetor bowl after you shut off the engine and then it drips into the throat of the carburetor.
 
I am using the Gross Jet on my B carb, it maintains it's level.
You may be seeing the float level creep which could be verified with a float level check.
Your jets could be too low, 9/16" below the edge as I recall, or the jet gaskets may not be sealing.

A's Always
Dave
 
I know there are some suppliers with the Viton float valve. I took the gross jet out and went back to a regular float valve. It still seaps, but I shut the fuel off when driving it into the garage and by the time I get it parked it shuts off. I don't like the smell of gas in the garage.
 
I had a Model "B" carb that did the same thing. After interrogating the usual suspects, I discovered that someone along the line had over-tightened the main jet plug at the bottom of the bowl. That had created a hairline crack to radiate from the hole beneath the brass plug. I ground a "v" through the crack as best I could and filled the crack as deeply as I could with an epoxy that you knead with your hands until it gets warm (i.e., begins to set up). I think the name was "Tough Steel" or something like that. It comes in a plastic tube and can be purchased at hardware stores. I allowed this to cure for a day or two and then filed the exterior bead level with the body. I then re-threaded the hole with a tap, and put the plug back in. That seems to have solved the problem. No more leakage. I didn't use JB Weld because I had back luck a couple times in the past when using it near gasoline. It eventually softened and let go.
Anyway, check for a hairline crack where I have indicated. If you need the exact name for the epoxy, I'll check at the hardware store. I don't have any left on hand.
Marshall
 
AL in NY said:
Ken/SC: It could be either one of two things happening. From your post, you feel it's the float needle valve. I would suggest that you remove the needle valve and seat. Then, with the very very lightest of blows, tap the top of the needle against the seat to try and create a better seal. If that doesn't fix your problem, I would lower the float level 1/8 inch. What may be happening is the cooler gas is expanding in the carburetor bowl after you shut off the engine and then it drips into the throat of the carburetor.
Click to expand...


FYI:

The "Tapping" procedure works with a stainless steel valve stem and brass seat.

Check to be sure that your's is steel first.

If it is a Viton valve stem ... tapping can damage the Viton (rubber) valve stem.
 
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