It cool to hear them run too. sounds a lot like a twin cylinder hit and miss engine. That one looks like it could be a runner. It has the protective tin can on the exhaust to keep rain out of the cylinders. When you fire it up the first pop sends it flying way up in the air. I think it is like 300 cubic inch displacement engine with only 2 cylinders.
A depression era money savings built in feature carried on for years. The tank is actually two different ones, the small one is labeled gas, and the big one is labeled fuel. You start it on gas, and once warmed up you switch to fuel, which was called distillate and cost less than gas. My dad said they used to run that in their cars too, but you had to burn it out of the tank because it would not restart cold on that.