The battery supplies the power necessary to start the engine when the ignition switch is is turned on.

A connecting rod employs a wrist pin to link each piston to the engine's crankshaft.

The four-stroke piston cycle of internal combustion engines starts with the piston at top of the cylinder head (top dead center or TDC) during the intake stroke. The piston moves downward in the cylinder creating a vacuum that pulls an air-fuel mix into the combustion chamber through the now open intake valve.

Combustion is the burning of an air-fuel mixture to provide energy. It requires the presence of air, fuel, and a heat source to ignite the air-fuel mixture. In the internal combustion engine that powers automobiles and trucks the combustion happens inside the engine utilzing a fuel like gasoline, diesel fuel, or natural gas.

Spark plugs receive current from the distributor and use it to spark combustion in the combustion chamber of a cylinder.