The spark plug is small, but it is not simple to construct. It has two parts: an insulator and a metal shell. 1. The metal shell is threaded for screwing into the cylinder; An insulator is arranged in the housing, which is connected with a central electrode and a wiring nut at the upper end of the central electrode to connect the high voltage wire from the distributor; A ground electrode is welded on the lower end face of the shell, and there is a gap of 0.6-1.0mm between the central electrode and the ground electrode. When the high voltage electricity enters the ground through this gap, a spark will burst out to ignite the mixture. 2. The key part of the spark plug is the insulator, if the insulator does not work, the high voltage will "copy the path" without passing the poles into the ground, resulting in no spark phenomenon. The insulator of spark plug must have good mechanical properties and resistance to high voltage, high temperature impact, chemical corr…