Spark plugs are simply insulated plugs that are screwed into the engine’s cylinder head to deliver the spark that ignites the mixture of air and fuel in the combustion chamber which in turn helps to start your vehicle. Spark plugs also transfer heat away from the combustion chamber. The spark plug sits at the top of the cylinder head. The piston first travels down the cylinder, drawing in a mixture of fuel and air. The piston then goes back up toward the spark plug, compressing the mixture. At the very last second, when the piston is at its fullest reach or top dead centre (TDC), the spark plug sparks and ignites the mixture. The piston is forced back down to create power for the vehicle, then pushed back up again to clear out the exhaust. At that point, the process starts all over again. A four-cylinder car will have four spark plugs; a six-cylinder car will have six and so on. A spark plug provides the spark that burns the fuel, its secondary role is to disperse heat. A spark plug’s ability to transfer heat to the cars cooling system is based on the length of the insulator nose and the materials used for the centre electrode and the insulator. Standard spark plugs in modern engines have a copper centre electrode core surrounded by a nickel alloy, which you can see at the tip of the plug. Inside the plug, the centre electrode is encased in porcelain, which helps transfer heat from the engine to the cooling system. Premium spark plugs make use of precious metals, like platinum or iridium, in place of the nickel alloy. These metals have higher melting points and will be more expensive! Here at AE Services in Sutton our service and MOT deal is very competitive and the spark plugs will be changed as part of this package. For more information go to: www.autoexpressservices.com.