40s

Nat · May 11, 2016

I bought a 40 S a few weeks ago and have been fixing all it's problems, and there are many as the PO didn't believe in fixing anything if a patch would do. Anyway, it runs poorly. It is strong but won't idle worth a crap, I've cleaned and gapped the plugs and cleaned and set the points and have done a fairly decient job of cleaning the carb, mainly cause I didn't find anything wrong. The carb to manifold casket was bad so I replaced it and none of this helped much. It does idle a bit better but still not even close to what it should. I've also noticed that when sitting there running it will condense water on the outside of the carb and on the bottom part of the manifold. What is causing this and what is the cure? I'm fixing this tractor to keep as I've always been partial to the M/40/420/430 series and want to have this one here to use plus I may take it to some local shows and such. Thanks, Nat

jeo46 · May 11, 2016

Probably the carburetor-Idle port is most likely plugged. You must carefully use the right size drill or small wire to clean all passages-I think there is a diagram of the passages on this site John Deere forum.

As for moisture on carb and intake this is common for Dubuque engines. Air is cooled at the higher velocity as it passes through them and humidity in air creates moisture on their outside.

Nat · May 11, 2016

Thanks, I didn't take the carb all the way down so that may be what the problem is. I'll give it a try and report back

Nat · May 11, 2016

Ok I took the carb off and cleaned it good and put new gaskets and seals and that did it. It reved to high cause when he rebuilt the motor he didn't set the governor to carb linkage so I was going to do that while the carb soaked. As normal I twisted the adjustment rod into and had to make a new one. You would know that the Hime joint had fine threads and I had to search for fine thread dies and the tap cause the only 1/4 inch NF thread nut I found had some buggered threads. Anyway I adjusted th gov rod and then finished the carb and it seems to run pretty well now. Just remember , everything takes twice as long when working on a 62 year old tractor cause you never know what else you have to fix while you're working. I ended up removing the hood , cowl, air cleaner and then the carb just for a simple cleaning. One of the reasons I want to keep this old tractor is it was made the same year I was born, so we already have age in common

40s

Nat

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jeo46

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Nat

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Nat

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