My dad used to collect those old engines. He had an Otto that was a dual fuel Diesel-gasoline. It had originally a radiator set up system. It was fuel injected and had a rotary governor, unlike the flyweight types on most other brands.
We used to dig them out of the ground where they slowly settled in over time. Had some barn finds, and, Even had one that had Edison original Nickle-iron batteries. Never found out what the electrolyte was, until the internet came into being. I used that one to charge batteries, and, just stuck a plastic tube from a regulated propane tank directly into the carb and adjusted it so the engine ran at optimum sounding revs, with no choking or lean-off timing-extra heat.
Only problem was the grease cup on the crank-con rod. and I had to re-pour the babbit bearing, two different times. This was the problem with must hit-miss engines, no steady long term oil lube to the crank-rod area. Then, the "throttle-governor" type was produced, so it fired on every other stroke (4 cycle) and had an enclosed (splash) oil lube system. He only ever had 2 of those. Wouldn't even drag them home.
These are the type Frank is describing.
He also had 1 windmill 8 cycle engine, that was used to run the pump jack below the turbine fan when wind wasn't available.
Had a nice 4 X 3 Rider-Errickson hot air (Sterling) water pump engine that would pump water from the ground up to a second story height water tank for house water pressure.
Sorry for the hijack, Frank