It is helpful to remember that most farm tractors built before 1950 were designed to run on “low-cost” “distillate” fuel, usually called “All-Fuel”. Today’s close cousin is Kerosene, not number one Diesel fuel. There IS a difference.
We notice that in today’s times, most collector/restorers are using gasoline fuel in their tractors. Further, it appears that in most regions of the country, gasoline blended with ethanol is what is available. The higher the concentration of ethanol, the more fuel volume is required.
It was our experience that back in the day, an engine originally designed for all-fuel did not run as smoothly on gasoline. Gasoline was for starting and warming up the engine before switching to all-fuel.
We have noticed some improvement by modifying the economizer circuit in the carburetor on our tractor. A removable plug is used.