Abstract: The ignition advance measuring device for internal combustion engines comprises a strobe lamp, a sawtooth generator and a threshold detector coupled to the generator. When the instantaneous amplitude of the sawtooth signal reaches a predetermined fixed value, the threshold detector produces a switching voltage. The switching voltage is fed back to the input of the sawtooth generator to initiate the rising portion of the sawtooth cycle. The falling portion of each cycle is initiated by the spark plug firing voltage. A knob calibrated in degrees of engine rotation is mechanically coupled to an adjustable circuit element in the sawtooth generator, which varies the duration of the falling portion of the sawtooth signal, thereby controlling delay between the occurrence of a spark and energization of the strobe lamp. The threshold level of the detector and the characteristics of the sawtooth signal itself are independent of average engine speed.