9N Ignition problem

The tractor runs smoothly for a few minutes, then cuts out to barely running. It gradually goes back to running smoothly, then cuts out again to barely running. I have no idea what could be the problem. Cold or warm makes no difference to it.

Any suggestions?

That is "classic description" of carburator ICING.

At certain times of the year, the very act of carburation, takes heat outta the air and iff't the local air is high humidity, then guess what? The cold carb FREEZES the humidity and can plugg the carb venturii jets with ICE.

This is a known phenomomen and small engine airplanes have a knob called what else? CARB-HEAT and is manditory on approach when you might need power for go-around. Even your belchfire V-8 has carb-heat; sometimes a pipe from the exhaust manifold to the airfilter snout; sometimes an under-the-carb crossover from one cylinderbank to the other.

Iff'n its a bother, try wrapping some aluminum foil around BOTH the exhaust pipe and the carb air intakepipe. Some rigg up a 3-4" tube with bailing wire to catch hot radiator air and blow it over the carb body. Simple, eh?..... ....Dell, the frostbitt

It has to be something simple. I don't know if the distributor has anything in it which could be out of adjustment or not. That's the only part I haven't touched.

The tractor blows black smoke and smells like gas when it's going on, so I wasn't thinking of a carb problem. Could be, though. It's worth a try.