Abstract: An engine operating time measuring apparatus is provided for use with an engine having an internal magneto-type electrical generator providing an ignition voltage. The engine operating time measuring apparatus includes a housing and a pair of terminals extending outside the housing for connection with the monitored engine and extending inside the housing for connection with the time measuring apparatus. A subassembly including power supply circuitry, a clock movement drive assembly, gear train and mechanical counter for displaying the engine operating time is accurately positioned and retained in the housing cooperatively provided by a counter frame and a plurality of keying and positioning rails formed within the housing. A low torque clock movement for driving the mechanical counter is generated by a crystal-based clock motor movement assembly.