Martin, I grew up about 1 mile from an oil well that was pumped by two of those huge engines, one had 9 foot flywheels and the other had about 6 foot flywheels. They ran 24 hours a day and pretty much 365 days a year. The larger one had a U shaped tube that went into and back out of the combustion chamber. You stuck a blow torch into one end of the U tube and flames came out the other, the engine was then turned over by a 6 cylinder Chevy engine connected to a differential that was cut off on one side and locked. The tire on the other side of the differential was litterally jammed up against the huge flywheel spinning it backwards, then it bounced forward, the tranny on the Chevy 6 was shifted to low to assist the big engine turning the right direction, it then bounced off the compression stroke backwards again, this was repeated four or five times until the flyywheel had enough momentum to roll over compression in the right direction. The tires that turned the big flywheels spent a lot of time making blue smoke from slipping on the steel flywheel, it was quite a sight for kid to observe. The big engine had a 6 inch exhaust pipe that made the gravel around it dance on each exhaust stroke. If that big engine quit in the middle of the night everybody in the holler woke up. That engine is going in to a museum in a few months. If anyone tried to use that engine now some whiney hand ringin left winger would make them shut it down. Those were good days when America was America.