Another Farmall...M

Well as much as I told myself no, I brought myself home another Farmall today from an auction. It is a 1948 Farmall M and will join my SH, SM, 300 and 400. I dont think anybody else noticed at the auction but it is a dual fuel model and it has the correct hood and small tank still! Tires and rims are in great shape and everything but the lights work (disconnected because they are not 12V). Anyway, I am not real familiar with the dual-fuel models and have never personally seen one before. Now was it made to start on kerosene and run on gas or???? How was the small tank hooked in to the carb (it is not hooked up now)? Should it have any other parts having to do with the dual fuel? Should there be a suffix on the serial number to denote dual fuel? Any help is appreciated! Thank you!!!

They start on gasoline and then switch over to kerosene or distillate once the engine is warmed up. The small (gasoline) tank should have a line to the filter under the main (kerosene or distillate) tank. They should have a radiator shutter and water temperature guage, the engine has to be kept hot and they also have a hot manifold with a lever to control the amount of heat transferred from the exhaust gasses to warm up the inlet manifold to prevent the lower volatility fuel from condensing in the manifold and cylinders. There should also be a heat shield to keep the manifold hot. If only running on gasoline the small tank can be used as a reserve and the shutters are kept fully open (or removed) and the manifold heat shield should be removed. The manifold valve should be set on cold. These are all covered in the Operators Manual. The Kerosene or distillate tractors did not have any serial number differentiation as in the early days this was the standard arrangement. When higher octane (70+) gasoline became more readily available, and cheaper, they often supplied the cold manifold (then only sort that seems to be available now)and the tractors had a X1 suffix after the serial number.

Most of those "dual fuel" tractors have had the manifold replaced with a gasoline manifold at some point. I have a Farmall H with the small tank which held enough gas to get me home a couple of times when the big tank ran dry!
If your M has the original head, it is a lower-compression head than the gasoline head. Lots of those old tractors had high-dome pistons installed during overhaul, and that made up for some of the compression loss.

If it left the factory as dual fuel it should have X3 somewhere on the engine serial# plate.MTF