4hp Callahan Jr

A very unusual Callahan Junior gas engine made by the W.P. Callahan Co. of Dayton, Ohio. These were built in three sizes: 4, 8, and 15 horsepower. These are hit and miss governed with the governor mounted in the flywheel and a pushrod to actuate the exhaust valve. Most Callahan engines have a sideshaft with a rear mounted governor that decouples the sideshaft during the miss cycles.
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