farmall 140 zenith carb.

i think i am a decent mechanic but these carbs keep aggravating me i cant seem to get them to stop leaking gas ...tractors run fine plenty of power ...i get the floats either just a lil bit off and either they wont leak at all or they seep gas out ugh .... need some advice here to make it simpler to do....

IHSMOKE, if you haven't already remove the float and submerge it in a pail of hot water for several minutes. If you have a hole in the float it will fill with water and you'll need to fix it or get a new one. Also, I've read on this forum that the black tipped needle jets are much better at sealing than the red ones.

I experienced the exact same issue you're having when [i:72a284c19c]trying[/i:72a284c19c] to rebuild the carb on my Farmall 460 gasser this past winter. I make no claims as to my mechanical prowess, but I have rebuilt several automobile carbs of various brands in my life. I have never experienced the problems I did with that infernal thing. It would be difficult to find a more simple working device, yet after following the directions for float adjustment that came with the rebuild kit and in the shop manual I could not get it to stop free-flowing gas. I had seen an add in Red Power Mag for Denny's Carb Shop, so finally in my frustration I bit the bullet and sent the son of Satan off to them for a pro rebuild. When I got the carb back I bolted it on and the old gal fired right up and ran great. It was a little pricey ($265.00), but to me it was well worth the money. Denny's boiled it out of course, re-milled the mating surfaces and removed and pressed in all those new little brass pieces. All things I couldn't do due to a lack of the proper tools/machinery. A pro carb rebuild will be the only way I go from now on when it comes to old tractors.

Good luck!

did all of the above ..... anyone know of a spec manuel for these carbs ? mine has the black tiped/ viton needle valve...

(quoted from post at 12:27:48 03/22/13) did all of the above ..... anyone know of a spec manuel for these carbs ? mine has the black tiped/ viton needle valve...

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The biggest mistake made when rebuilding any carburetor is ASSUMING the needle valve and seat are ready to be installed right out of the package.

They are NOT. There is a residue left over from the manufacturing process, and that residue is sticky. It causes that brand new needle valve to hang up in the bore of the seat, and then you have problems. An aerosol can of carb and choke cleaner will get rid of that residue, and if you want to take it one step further, when the needle and seat are both dry, give 'em a shot of silicon spray lube, and THEN do the installation.

I too have struggled with a Zenith on a 140. Either it would overflow gas and flood, or it would not take gas at all.

I must have disassembled and reset the float level a good 8 or 10 times. Thoroughly frustrated I finally discovered the viton tip on the new needle valve was molded off-center. Also I found small dimple worn into the float arm. This was catching the bottom end of the needle and preventing the float from operating properly.

Solution was to polish out the dimple in the float arm, then stick the old needle and seat back in.

But finding the right float level was still difficult. Took a bunch more trial and error adjustments to get the tractor run without leaking.

Most miserable carburetor I've ever worked on...