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Old 10-10-2019, 11:47 PM   #1
SBJ
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Default Any carburetor wizards on here?

This isn't at all related to what we generally talk about on here but I thought I'd ask. Basically at work we have a really old single-cylinder engine. For reference, Eisenhower was in his first term when it was made. It has been rebuilt at least once in the past and I don't think there's anything internally wrong with it.

Basically it was running very poorly and the ancient carburetor on it was leaking out of every place it could leak from. I managed to find a new one for it and installed it the other day. Initially it ran, but would rev up way beyond what is needed or probably good for it. I found that the throttle plate would get stuck open, so I adjusted the linkage on it to prevent that from happening. For how we use it there's no way it would ever need to run at WOT anyways. The only caveat to that is that the throttle plate needs to be open for it to start. Basically how it works is as soon as the engine starts the governor pulls on the linkage closing the throttle valve.

I pulled the plug out and it was bone dry, so gas isn't making it into the cylinder. It has spark. However, gas is dripping out the bottom (it's an old school updraft carb) so it's at least making it through the jet. Any ideas as to what the problem might be? Thanks everyone.
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Old 10-11-2019, 01:08 AM   #2
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Float stuck?
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Old 10-11-2019, 04:55 PM   #3
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I would look into a comparable sized 'modern carburetor' or atleast something that is serviceable
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Old 10-11-2019, 07:37 PM   #4
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Carb is brand new. Zenith 12522 if that's of any benefit. The original one has long since gone out of production.
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Old 10-11-2019, 10:24 PM   #5
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Does the float need adjustment? Try re-adjusting the plate?
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Old 10-12-2019, 07:31 PM   #6
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Alright, well I thought I'd update and say thanks to everyone who helped. It turns out the problem was more extensive than the carb not working as it should. I actually threw the old one back on temporarily because it did run (albeit not spectacularly) before. The spark was also pretty weak so I tore into the equally ancient gear-driven magneto and found that the points were burned up and the gap was probably twice what it should be. They do actually still make points for these so I'll have to get a set in the future. In the meantime I sanded them down to clean metal, re-installed and set the gap on them where it's supposed to be.

Then if that wasn't enough, it now has a nice strong spark but the plug wasn't firing. It turns out that the center electrode had also burned up internally and the plug (brand new NGK) wasn't sparking. I found an old one lying around so now it at least runs again. I will probably attempt to put the new carb back on once we don't need it running for awhile.

Once again, thanks to everyone who helped.
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