1942 Farmall A: Surging/Hunting

I have this 1941 Farmall A. Been nothing but problems sorting out since last late summer when I got it. Would just cut out and die, and would not restart. Has had new: Points, Condenser, Rotor, Cap, Spark Wires, Coil, new Coil Tested, spark plugs, regulator, generator rebuilt, gas replaced, another new set of points and condenser...

Lastly, I have replaced the 6V battery as it would not hold a charge.
Things slowly have gotten better. But lastly it would not stay running when it warmed up under load. So I got a carb rebuild kit, cleaned the carb, soaked it for 3 days in the can of carb cleaner, and did the rebuild. Installing the rebuilt carb; in "testing" under load when it warmed up it would begin to die and if I choked it, it would continue to run. So I decided to purchase a new carb...

There was always a governor surging or hunting problem; so I installed the new carb, ran without adjusting the linkage and the surging started under load quickly and now it's so bad with the new good carb, I cannot keep the tractor running with the tractor under load. So adjusted the linkage to the carb and made sure it's not binding on the block also, but same surging or hunting problem. If I grab the linkage from governor to carb, it stabilizes and runs fine. I can run the engine with my hand on the linkage to stabilize it, running fine, wide open, half, or at idle. This surging or hunting happens under low, medium, or full throttle, and eventually stalls the tractor under load if left unchecked by clutch. I can unhook the "load" (harrow) and drive the tractor into the shop OK.

http://youtu.be/63xse-V7AOU

Since I'm at wits end, any intelligent suggestions and help as to what to do next is appreciated to solve what I think is the last problem in this tractors complex issues...

Weak gov spring or sticking gov either one will cause one to hunt/buck like you describe. Be sure you got the gov adjusted to the carb right too. Make sure when the throttle is wide open, the carb's butterfly is also wide open, and make sure when the throttle is fully closed, the butterfly is as well.

RE: Gov/Carb Setup, Both appear correct, Open & Closed Butterfly.

When you speak of the Gov. Spring: which and what as I am not so familiar, but I own wrenches. Any detailed help apprieciated.

-Sugar Tractor
Visit - Google: IHartHatvest

Remove the acorn nut and the jamb nut then with a screw driver back the screw out and check the bumper spring in the screw if its bad replace you can get new ones at your dealer. That bumper spring is for surging and that could be your problem. With the engine off remove the pin on the arm going to the carb. Now open the throttle and hold the yoke that the pin holds to the arm and adjust it so when the carb is held open the pin will go back in. You mite need to put a vicegrip on the linkage so you can turn the yoke. Its a good idea to remove that rod from the carb and get those threads clean so the yoke will turn easy as they usually arebound up with paint,rust ect. This will make sure your linkage is then adjusted correct. The bolt on top of the gov is the one to adjust for top RPMs

I would also check for vacuum leaks such as a bad gasket or a crack somewhere. I used to have a hunting, lack of power problem. Turned out to be a vacuum leak caused by a stripped main jet plug.