float valve problem

[Marty Levenson]

Dear Don,
Last fall I wrote to you concerning two carb problems: fuel leaking after shut down and needing to keep the rich/lean mix screwed in tight to obtain a good idle. I think I have solved the first part.

Last weekend I disassembled my carb and found that the silver float valve pin was completely shiny metal, whereas the one in my rebuild kit has a rubbery, black tip. I believe that cleaning my carb with laquor thinner last fall (following bad local advice) may have dissolved the rubber.(?) Would that not explain the inability of the foat valve to seal? Have not reassembled yet to test. I am wondering if there is any connection to the excessive leanness problem, or is that likely a separate issue. I still plan to check that the upper/lower faces are true (aluminum carb: mod 68).

Any thoughts greatly appreciated,
Marty (Vancouver)

[Don Moyer]

Marty,

All-metal needles were only used (at least by Zenith) in the early model cast iron carburetors, and to the best of my knowledge, they were not in common use by anyone since the 1960's.

I'm not sure how resistant the rubber-tipped needles are to various solvents, but you should be able to get an idea how well yours may have survived by examining it with a magnifying glass. I like the magnifying glasses that you can get from most local stationary stores that contain a small light in the handle.

In any case, if the needle of the float valve is leaking, the carburetor would tend to run on the rich side.

Best regards,

Don Moyer

[Marty Levenson]

Dear Don,

Thanks you for your reply. I don't have the old needle in front of me, but I will certainly take a hard look at it today.

As our engine is from 1967, but the current aluminum carb was only installed two years ago, your information makes me question my conclusion that the rubber dissolved...it seems just as likely that in my previous rebuild I used an all metal spare from one of my old rebuild kits. If so, because the carb only leaked fuel into the throat recently, your original idea (last fall) that it was a bit of dirt keeping it from sealing seems more likely.

Thanks again,
Marty