Interesting old Rumley Oil Pull tractors. These ran on all types of kerosene instead of other types of fuels like gasoline or diesel. The engines had a huge displacement and some had pistons 10" in diameter and a 12" stroke. I tried to find some details about these, and found limited specifications about them. They used oil instead of water for cooling because the engines needed to run much hotter than gasoline engines to ignite the kerosene. The engines are often started on gasoline, then switched to kerosene once it warmed up. Water was also injected into the engine to prevent predetonation under heavy loads and it was common to burn 1 part kerosene and 1 part water in these conditions. These were used a lot for threshing operations in the U.S. and Canada, and many were in operation during WW2 to help feed the nation. I got a few shots in slow motion at 300 frames per second.