Book Description

"Many types of electric ignition systems have been developed, used, and discarded in favor of systems less expensive and more adaptable to internal combustion engines, Two types which might be classified as high-tension, jump-spark systems are in common use today. These two systems are (1) Battery-coil ignition used mainly on automobiles, and (2) Magneto-ignition used extensively on aircraft engines. A considerable amount of work has been done to determine the extent to which the character and intensity of the electric spark affect the ignition process. This work has revealed that a certain minimum amount of energy is required from the spark before combustion will occur. Any excess energy over and above that required for combustion appears to have no effect on engine performance. It has also been found that there are many factors which influence the voltage necessary at the spark plug to produce the required spark for combustion. Included in these factors are spark plug electrode temperature, engine speed, engine compression ratio, intake manifold pressure, fuel-air ratio, and amount and nature of lead-compound deposits on the electrodes. The function of the ignition system, therefore, is to provide a spark in the cylinder with sufficient energy to produces combustion under the maximum adverse conditions--Introduction, leaves 1-2.