Zenith Carburetor M...
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Zenith Carburetor Model L or version thereof technical questions

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On my 1915 White Model 45 the carburetor was made by Zenith for White, and from what I can see in Dyke's Automobile Encyclopedia, is very similar to a Zenith Model L or Model O.  I have a problem that I cannot seem to solve.  The engine starts and runs just fine and there is no external gasoline leakage when the engine is either running or stopped.  However, a when the engine is shut off a leak develops that wets the carburetor body around the secondary or idling well.  On this model the well is open to the atmosphere and has a fine mesh brass screen at the top of it  The gasoline seems to run out of the secondary or idling well at the juncture of the well and the screen, run down the carburetor body and drip off of the compensating jet access plug.  The only time this leakage occurs is when the engine is shut off.  It doesn't seem to matter if the throttle is fully closed or partially open when the engine is shut off.  The leak is not a large one and dries up in a short time.

I'm looking for ideas as to why this happens and how to stop the leakage.  I wondering if there is a possibility that the air screw which controls the idling mixture by changing the air flow through a hole between the secondary, or idling well, and the carburetor body might not be adjusted correctly?  This hole is covered by the butterfly when the throttle is closed and when the throttle is partially open according to Dyke's "with the butterfly partially open, the suction at this point is powerful and draws the well full of gasoline into the cylinders, effectively priming the engine.  Also, by the introduction of this secondary well, which measures the gasoline used in running idle, a perfect mixture is obtained at very low engine speeds".

I'm attaching some photos showing the carburetor information on the float bowl cover, showing that the carburetor body is completely dry when the engine is running or stopped, and one showing the leakage from the idling well when the engine is shut off.  I've also included photos of the Zenith information from Dyke's.

Zenith Float Bowl Cover
Dykes 18th Ed Pg 131
Dykes 18th Ed Pg 132



Posted : July 3, 2023 3:02 am
Posts: 2
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Charles, This may seem basic but if you have inspected closely for any hairline cracks, you should be sure the needle and seat are stopping fuel when the float presses the needle down.

Posted : September 12, 2023 1:42 am
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Topic starter

Thanks Roger.  That may be a possibility, but I don't think so as I've modified the needle and seat with a new viton tipped needle and a matching seat.  Right now I've temporarily replaced the original carburetor with a newer model Zenith and plan to completely inspect the original one and re-check and/or adjust the float level during the winter while I have it on the bench.  Then I'll go from there as a new starting point.

Posted : September 12, 2023 3:54 pm
Posts: 2
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"Modified needle and seat" jumps out at me. Again Charles, if no hairline cracks, look real hard at the seal between the new seat and the carb casting. That viton tipped needle does a fine job, however the new brass seat mating to the carburetor bears looking at.  Your White is a real fine automobile, enjoy it!

Posted : September 12, 2023 6:20 pm