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Spark Plugs

The basics of a spark plug on a comustion motor

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Spark Plug Basics Diagram Parts Components

A spark plug fits on the cylinder head of an engine. There is usually one spark plug for each cylinder in a car. The spark plug is used in internal combustion engines to ignite fuels like gasoline. It works by the coil creating a charge that must be between 40,000 to 100,000 volts that travel s across the gap found at the end of the spark plug. There are ceramic insulators in the plug to isolate the spark, so it doesn’t go anywhere else in the plug.

Often people will refer to a plugs heat range. This is describing the amount of heat that is found in and around the spark plug itself. Hot plugs have a smaller contract area with the metal, and are found to thread farther into the combustion chamber. Cold plugs have a larger contact area with the head to spread the heat around, and do not thread as far into the combustion area.

Spark Plug Basics Diagram Parts Components

The parts of the spark plugs are terminals, ribs, insulator, metal case, seals, insulator tip, and side and center electrode. The terminal is where the spark plug copper wire attaches. The insulator is made out of porcelain and is used for insulating and extending the terminal to the cylinder head. The ribs also insulate by using “ribs” to cause more resistance to stop electricity from going to the metal case. The metal case removes heat from the insulator and passes it to the cylinder head. Seals make sure nothing leaks from the chamber. The insulator tip can withstand 650 C and 60,000 Volts. The electrodes cause the spark to cross a gap left at the end of the spark plug, causing ignition of the fuel in the cylinder.

For more information about using the spark plugs to diagnose the health of your motor, or to aid in tuning your motor, be sure to check this article HERE.


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