Cockshutt 540 carburetor problem

Several months ago I disassembled/cleaned the 540's carburetor (Zenith 68J8) due to persistent gas seep from drain in the bottom of intake tube, found a visible speck of dirt in one of the small jets, reassembled and started/ran normally. The leak persisted however and, thinking the float valve with its rubber tipped needle might be at fault thanks to ethanol in the fuel, I purchased a kit and rebuilt the carb, after which the tractor started/ran normally. But the leak persisted, so I recleaned the carb and rechecked the float setting, checked/confirmed the fuel shut off valve at the sediment bowl slowly leaked, and replaced it with new sediment bowl assembly. The tractor started/ran normally, so I changed shut down routine to include running the carb dry. Several weeks later, the tractor didn't start due to flooding. After shutting the fuel off, I elected not to drain the carburetor bowl and have been rewarded with the fuel seep from the intake drain again. Other than thinking the new rubber tipped needle is at fault, I'm at a loss to wonder what's going on. Is there a source these days for the old style all metal needle that might be impervious to the effects of ethanol?

Check with Phil Heisey see if he has any. 2152568651.

The Cockshutt 540 has the Continental F162 motor, so you can see that it is on the list at the link below:
Zenith series 68 carb

I have been using ethanol for over 25 years and have NEVER had any issue with it. Also worked on a dirt late model crew that ran e-98 for 10 years with no problem. I use e-30 in my 05 Dodge Stratus and makes 24-26 mpg.

I haven't either, but I don't know what kind of float needle is in my carburetor as I'm not sure I have ever been in it since I bought it in the Summer of 1964.

Thanks to all for your responses. The link to Mike's carbs prompted a search for Viton tipped needles, which led to several helpful comments, some from past YT threads. Turns out Viton has been widely used for 40 years or so, isn't any kind of rubber, and is nonreactive to ethanol, making the needle itself less consideration than how well it seats. Two schools of thought exist - one suggests a thorough cleaning of the needle tip and seat with aerosol carb cleaner before installing in the carb, and another recommends tapping the needle in the seat; both methods to encourage a good seal. I've done my fair share of carb rebuilds and have done neither in the past. Other comments remind me to check the bowl gasket for all holes to be where they should be, and to test how well fuel is shut off after removing the bowl in situ. So I have several more avenues to explore now.

Belated follow-up to the carburetor issue, now successfully resolved after several disassemblies/reassemblies. At the end of which I was reminded that the old "measure it twice" axiom applies to float adjustments too, but one has to read the ruler correctly. Additionally, new parts aren't necessarily guaranteed to be made well, especially these days - the new needle and seat in the 2nd rebuild set simply weren't up to the task. And lastly, Permatex 85420 gasket dressing is vastly superior to grease or vaseline if one persists in taking these things apart numerous times.

MV

Glad you got it sorted. I too have discovered the quality woes plaguing carburetor kits these days. I have had better luck lately using Mike's or Carb Dr. kits.