…are produced by means of breaker points controlled by a revolving distributor cam. When the points are in contact they complete an electrical circuit through the primary winding of the ignition coil. When the points are separated by the cam, the primary circuit is broken, which creates a high-voltage surge…
Read Morespark plug, device that fits into the cylinder head of an internal-combustion engine and carries two electrodes separated by an air gap, across which current from a high-tension ignition system discharges, to form a spark for igniting the air–fuel mixture. The electrodes must be able to resist high temperatures, and the insulator separating them must withstand high temperatures and also an electric stress up to several thousand volts. Spark-gap length affects the energy of the spark, and the shape of the insulator affects the temperature of operation. When too cool, operation leads to carbonization and short-circuiting of the gap; when too hot, there may be preignition.
