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Curtis, the term "all-fuel" is a little confusing. Deere did use the term "all-fuel" but maybe multi-fuel would be a better word. ~To understand what it is, & more impotently [why use it] we have to go back before World War-II.... Before WW-II catalytic fuel cracking wasn't used & that meant for every gallon of gasoline produced there was a lot of non-gasoline type products left over, some of those products were distillate & other less refined but burnable fuels like heating oil, & other similar less refined fuels.... Because less gasoline could be extracted from each barrel of crude oil there was a lot of [less useful types] of fuel left over. Those lower quality type fuels were often quite a bit cheaper to purchase than gasoline. Many manufactures & farmers soon found that overall tractor operating cost could be significantly lowered by burning this lower quality fuel. In some areas the cost of distillate type tractor fuels were less than 1/2-1/3 the cost of gasoline. ~In the late 1920's through the early 1940's tractors that could burn this cheaper [tractor fuel] was a big selling feature & some manufactures like John Deere took advantage of the cheaper distillate type fuels available & produced a lot of tractors capable of utilizing this cheaper lower quality tractor fuel. Deere was especially good at producing tractors that could efficiently burn that less refined distillate because of their low RPM long stroke 2-cylinder engines that used exhaust heated SHORT runner intake manifolds & convection cooling. ~While Deere did a good job of designing slow turning engines that could take advantage of the slower burning distillate fuels the engines did require lower compression to effectively use the lower octane type fuels & the cooling systems had to be set up to keep the engine operating temperature above 190° for the fuel to ignite & burn properly. The other limitations of the harder igniting lower cost distillate type fuels was it's inability to start cold. Most manufactures added a second [gasoline only tank] so the engine could be started on gasoline then once the engine reached operating temperature [usually around 190°F] a valve could be turned & the engine switched over to the harder igniting tractor fuel. ~Some of the disadvantages of using those less refined tractor type fuels was more crankcase contamination due to some of the unburned fuel getting by the piston rings, a real pain to re-start the tractor if it was stalled while burning the tractor fuel, more fuel valves to turn & position correctly, the fact that the engine temperature had to be continually maintained at or above 190°F to operate correctly, & the tractor had to either be switched back over to gasoline before shut-down or the fuel had to be shut off & the carb run out of fuel. ~Any questions just post back.....
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