Zenith Troubles

[Lefthander1930]

Trying to fix a leaking carb. Went & purchased a carb kit. After finishing the carb I had a extra jet. Call & was told that some carbs had brass inserts & mine didn't. I looked ten time where I could have messed up. Part 2, leaking out the bottom hole. Float mess up I guess. The easy for Dummies to set the float @ 5/8 ?

Thanks

[Brentwood Bob]

Check to see you didn't leave an extra gasket in the main jet.

[Tom Endy]

The early Zeniths have a brass seat that screws into the base of the GAV tunnel. They look similar to the comp jet, but are definitely not the same, so don't mix them up. Ford eliminated the brass seat because people had a tendency to close the GAV valve too tight and the needle would seize in the seat and when they backed it out instead of opening the valve they unscrewed the seat. Ford then just used the cast housing material as the seat, worked fine.

The extra "jet" in your kit is probably the GAV seat.

Most Zenith leaks are due to the float valve not set at the correct height or not holding. This allows the fuel level in the reservoir to rise above the tips of the main and cap jets. It then spills over the tops and runs into the throat of the carburetor and exits through the little weep hole in the bottom. Best to install a Viton tip float valve, they hold better.

Tom Endy

[whirnot]

Also check to make sure the cap jet is fully seated. The jet tool can sometimes jam against the boss, and you think it is seated, but it isn't.
And I know this because.....

[Wick]

Check the top of the bowl for a hairline crack. Usually on the engine side of carburetor. Will weep fuel down and drip off bolt. I went through 1 carb 4 times before I found it.

[BTERRY29]

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I’ve replaced the shut off valve and 2 float valves chasing this same issue. Even the Viton leaked. Float set to 5/8. Ive finally resulted to just turning off the fuel valve and letting it run for 15 seconds or so then shutting down to empty the bowl. No leaks. Unless you are leaking while running.


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[BRENT in 10-uh-C]

Originally Posted by BTERRY29

I’ve replaced the shut off valve and 2 float valves chasing this same issue. Even the Viton leaked. Float set to 5/8. Ive finally resulted to just turning off the fuel valve and letting it run for 15 seconds or so then shutting down to empty the bowl. No leaks. Unless you are leaking while running.


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If you replaced the Shut-off valve and immediate continued to see leakage, then I would expect that your tank cap is not venting properly and is causing excessive pressure in the tank to minimally pressurize the fuel. A tank that is rusty internally will cause the barrel valve to score due to the rust sediment, and those are difficult to prevent seepage, but it generally takes an added pressure outside of just gravity head pressure to push the Viton tip off of the seat. Especially when you know your new float is creating plenty of pressure onto the needle.

Oh, and BTW, great username!!

[JayJay]

Originally Posted by whirnot

Also check to make sure the cap jet is fully seated. The jet tool can sometimes jam against the boss, and you think it is seated, but it isn't.
And I know this because.....

And to further complicate things, if you install the main jet before you put in the cap jet, the tool will bind up against the main jet and make you think the cap jet has seated before it really has. I get around this by not installing the main jet until after I've installed the cap jet.

JayJay

[Ed in Maine]

When rebuilding I always rub the area where the float valve stem hits the brass float. It will create a small divot in the brass. Scrub this area with 320 (very fine sand paper) to remove any ridges in the brass. The setting is 5/8 in. in the literature but I like to go a bit deeper 11/16 in. but less than 3/4 in. This practice will give you a bit more leeway before you spill over the Main and Cap Jets especially if you are parking up hill! Usually I find that you need two float valve gaskets to get a decent bowl level setting. Ed

[JayJay]

Originally Posted by Ed in Maine

When rebuilding I always rub the area where the float valve stem hits the brass float. It will create a small divot in the brass. Scrub this area with 320 (very fine sand paper) to remove any ridges in the brass. The setting is 5/8 in. in the literature but I like to go a bit deeper 11/16 in. but less than 3/4 in. This practice will give you a bit more leeway before you spill over the Main and Cap Jets especially if you are parking up hill! Usually I find that you need two float valve gaskets to get a decent bowl level setting. Ed

I've found that some upper bodies have such corrosion on the float valve seat that you will never get a liquid tight seal. I deep six those uppers.

JayJay