Point of Ignition

—The moment at which the mixture in a gas engine cylinder is ignited, and which corresponds to a certain point in the cycle of operations, should be neither too early nor too late relatively to the ending of the compre ion and the beginning of the power strokes. When the moment of ignition occurs too early, the maximum pre ure of the explosion is reached before the end of the compre ion stroke, thus retarding the motion of the piston, increasing the friction on the crank pin, and consequently reducing the brake horse power. When the moment of ignition occurs too late, the mean effective pre ure is reduced, and consequently the brake horse power also. The highest efficiency is obtained by adjusting the point of ignition to suit the amount of comre ion, and the speed of the engine. As an interval of time, no matter how short, must elapse between the moment of ignition and the moment of maximum pre ure in order to prevent tke delivery of a dead blow on the piston, the moment of ignition should occur immediately after the crank pa es its inner dead center at the end of the compre ion stroke.