Another benefit of these screws is their strength and stability
When the engine is running, the ignition coil receives a signal from the engine control unit to fire at the correct time. The coil then rapidly builds up a magnetic field within the primary winding when the signal is received, and when the signal is cut off, the magnetic field collapses rapidly, inducing a high voltage in the secondary winding. This high voltage is then sent to the spark plug, where it jumps the electrode gap, igniting the air-fuel mixture in the combustion chamber.
For more detailed information, please see the following:
Maintenance and Replacement of Valve Cover Gaskets
What is Oil Seal
Broad chemical resistance, except against liquid alkaline metals and fluorine gas under pressure. Good sliding qualities, low wear and tear. Temperature range from -200 °C to +260°C. PTFE has hardness of approximately 95 °Shore and installing these O-rings in split grooves is recommended or alternatively the use slit or sheathed types due to the low elasticity.
HALOGEN