EVOLUTION OF THE SPARK PLUG

Dominion, Volume 20, Issue 52, 25 November 1926, Page 14

EVOLUTION OF THE SPARK PLUG

INSTRUCTIVE ILLUSTRATED LECTURE. The various stages in the manufacture of a spark plug, from the rawmaterial to the finished product, formed the subject of an interesting and instructive lecture given by Mr. C. A. Speers, of the Champion Spark Plug Company, Windsor, Canada, in Hope Gibbons Ltd.’s building last evening. The lecture was illustrated by means of a motion picture film, “The Story of a Spark Plug,” a production made under the direction of the United States of America Department of the Interior, Bureau of Mines, to aid in the conservation of petrol. The lecture was highly interesting to motorists, a feature of the film being a slow motion picture of. the electric current passing down the wire coils,, through the electrode of the plug and igniting the gas in the cylinder. Mr. Speers pointed out that the continuous and strenuous service to which a _ spark plug was subjected over, a period of a year or in eight or ten thousand miles’ running caused it to lose _ efficiency. Carbon was burned into the surface of the insulator, and part of the available electrical energy was wasted by short circuiting through this surface deposit. ■ The electrodes gradually became oxidised or pitted, setting up resistance to the electric current. As a result, only part of the electric current jumped the spark gap, and although ignition took place the combustion was slower and the fire spread less rapidly because of the reduced heat value' of the ■ spark. Only a part of the gas -was consumed, the mixture was only partially burned and the unburned portion passed out of the exhaust valve. That was why it was real economy, to instal new spark plugs at least otice a year. The y would pay for themselves in oil and gas saved and give more power, greater speed and quicker acceleration.