Tractor Repair: old Farmall tractor, farmall tractor, fuel flow

Question
I have an old tractor and its shutting off after running for a little while, I've checked the filter and the spark  and both are good the worst part is after shutting off it starts right up and runs smooth both before and after it shuts down ?
Thanks

Answer
Sounds like the carb might need rebuilt.
But first check the fuel flow going to the carb. It shoould be a good steady stream.
Does it have good spark immediatley after it shuts down, could be bad points.
Bad points will get hot, open up and kill the engine, then as soon as they cool the tractor will start right up
Let me know what you find out.
Sorry it has taken so long to answer.