Today, he and Keith Berry fired up this 1-1/2 horsepower Chore Boy engine this morning. The engine was built by Associated Manufacturing Co. of Waterloo, Iowa.
Here's what Wikipedia has to say about the engine's name:
The name comes from the method of speed control that is implemented on these engines (as opposed to the "throttle governed" method of speed control). The sound made when the engine is running is a distinctive "POP whoosh whoosh whoosh whoosh POP" as the engine fires and then coasts until the speed decreases and needs to fire again to maintain its average speed.