allis chalmers 170 gas, rough running

[tleonard]

I have an allis chalmers 170 gas engine tractor. It has problems running. At first start-up, it will run fine. After it starts to heat up, it will basically only run at idle. When I try to give it gas, it coughs and sputters and will barely run.
I have set the carbureter to basic settings from maintenance manual, replaced the plug wires, and checked the timing, which appears to be pretty close when it is running good enough to check it. Any help?

 

[RickB]

I worked on a gas 180 this summer that gave me similar fits. Turned out there were corroded connections on the ignition switch that caused voltage drop in the ignition circuit. Tractor would run like a Swiss watch with a jumper wire from the battery to the + side of the distributer. Anything less than 8 volts input to the distributer (through the ballast resistor) on the 180 I was working on, and it wouldn't run right.