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

Cylinder number and arrangement depends on the purpose of the engine. Smaller (four and six cylinder) engines in front-wheel drive vehicles often use an inline design which orients cylinders vertically over the crankshaft and aligns them in a row. Other common orientations are a horizontal/opposed design which places cylinders flat facing each other with the crankshaft between them and a V-type design common in six and eight cylinder engines that features one cylinder head per block of cylinders oriented at a 60 to 90 degree angle to each other with the crankshaft at the bottom of the V.

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.

Once the engine is running, the alternator provides electrical current to recharge the battery and power the electrical system. The alternator is driven by the engine's crankshaft and produces alternating current (AC) which is then fed through a rectifier bridge to convert it to the direct current (DC) required by the electrical system. A voltage regulator controls the output of the alternator to maintain a consistent voltage (approx. 14.5 volts) in the electrical system regardless of load.

Fuel injection has replaced the carburetor as the primary automobile fuel delivery system. The main difference between the fuel injector and the carburetor is that fuel injection atomizes the fuel by forcibly pumping it through a small nozzle under high pressure while a carburetor relies on suction to draw fuel into an accelerated intake air stream.