The basics of a spark plug is that it must perform two primary functions.

• To Ignite the Air/Fuel mixture.
• To Remove the heat out of the combustion chamber.

    Spark plugs transmit electrical energy that turns fuel into working energy. A sufficient amount of voltage must be supplied by the ignition system to cause the spark to jump across the spark plug gap, thus creating what is called Electrical Performance.

    Additionally, the temperature of the spark plug's firing end must be kept low enough to prevent pre-ignition, but high enough to prevent fouling. This is called Thermal Performance and is determined by the heat range of the spark plug.

    It is important to understand that spark plugs cannot create heat, only remove it! The spark plug works as a heat exchanger, pulling unwanted thermal energy away from the combustion chamber and transferring the heat to the engine's cooling system. The heat range is defined as a plug's ability to dissipate heat. The rate of heat is determined by:

• The insulator nose length.
• Gas volume around the insulator nose.
• Materials and/or construction of the center electrode and porcelain insulator.

    Spark Plug Function

• Battery sends low voltage to Ignition Coil.
• Ignition Coil transforms current to high voltage.
• Distributor or Computer distributes voltage to each spark plug in turn.
• Spark Plug generates a spark between gap of ground and centre electrode.
• Compressed fuel/air mixture ignites & explodes creating working energy.

    Important factors are the timing of the spark, the correct heat range and the correct spark plug gap.

    Challenges for good spark plug operation include:

• Operating in high temperature, high pressure environment.
• High oxidation threat.
• Prevention of misfiring/non-firing.
• Cold starting.

    Correct spark plug choice and maintenance is essential for the optimum running of your engine. Diagnosis of the appearance of a spark plug is an effective method of evaluating how the engine is functioning and what improvements can be made.

    It is important to use the spark plug type recommended for your vehicle. Those dimensions have been tested and approved for that model. A plug of different dimensions may cause harm to the engine.

    However, you can usually cross-reference to a different material from nickel to platinum or iridium, or between brands. Please refer to cross-reference lists recommended by the major brands. If your vehicle is not set to standard specifications you may need a different plug.