Defects During Installation
DEFECTS DURING SPARK PLUG INSTALLATION
Exceeding the recommended tightening torque during installation in the engine causes stretching the shell in the neck of the thread and damage to heat conduction from the insulator nose through the sealing ring to the shell and the cylinder head. Then, the insulator nose is overheated, which results in ignition advance in the combustion chamber. High temperature in the combustion chamber because of ignition advance damages the spark plug and can cause serious damage to the engine.