The firing order of the cylinders in an engine is different than the cynlinder numbers and can be found by observing the order in which the intake valves open.

Ignition timing defines the point in time at the end of the compression stroke that the spark plug fires. Measured in number of degrees before top dead center (BTDC), the exact point that the spark plugs initiate combustion varies depending on the speed of the engine. The timing is advanced (the spark plugs fire a few more degrees BTDC) when the engine is running faster and retarded when it's running slower.

A head gasket is a gasket that sits between the engine block and cylinder heads to seal the cylinders to ensure maximum compression and avoid leakage of coolant or engine oil into the cylinders.

Because a compressed spring will ex­tend violently, shock absorbers must be used to dampen the spring’s compression and extension cycles. Struts combine the spring and shock into one unit

The fluid reservoir stores the brake fluid that the master cylinder uses to maintain hydraulic pressure.