The Jumping Off Point

This is the point where it either happens just as it should, doesn’t happen at all, or maybe just sort of happens in a way that is so insignificant that it hardly has an impact on anything. Either way it’s the point of no return. The jumping off point that I am talking about is the spark plug.

This is the place where the spark that ignites the air fuel mixture enters the combustion chamber. This is the last component in what’s known as the secondary ignition system. The energy that powers the wheels of the car originates in the gasoline, but if the spark does not meet up properly with the fuel and the air after they are already mixed, then the energy conversion known as combustion doesn’t occur. Or at least only partially occurs. Anything less than the best when it comes to combustion leads to low power, high emissions, and poor fuel economy.

 

Even though all spark plugs look the same they aren’t. Subtle differences in design change the way the spark jumps the gap. The spark must jump from the center electrode to the ground electrode, and it must do this with the cylinder under pressure. The gap is usually no bigger than about .060 inches, but the higher pressure in the cylinder requires the spark to jump the gap with a much higher voltage than what would be required if the cylinder was not under pressure. Secondary ignition system voltages usually run somewhere between 12,000 and 60,000 volts but can go higher under some circumstances.

The center electrode is generally made from a copper alloy, and in the old days this copper went all the way to the tip of the electrode. The spark would jump from the edge of this center electrode and not from the middle. The copper resistor spark plugs would have a tendency to wear out more quickly because the tip would get so hot it would burn away a tiny bit of metal every time the spark would jump. Newer spark plug electrodes use metals such as platinum or another metal related to platinum known as iridium. These metals resist the heat and corrosion caused by the spark and combustion and last much longer. Regular spark plugs wear out in about 30,000 miles but the platinum tipped plugs can last about 100,000 miles.

So what kind of spark plug should you put in your car when it comes time for some new ones? The answer here is very simple. Use the plugs that the car was designed to use. This doesn’t just apply to the design of the plug, but also to what brand to use. Many aftermarket spark plug manufacturers make spark plugs in all sorts of designs and with the proper dimensions and heat ranges to fit in just about any kind of engine; however, just because the plug fits in the hole, and the guy at the parts store said it was for your car, doesn’t mean that it’s the right plug.

Some of the original equipment spark plugs are made by companies such as AC Delco, Motorcraft, Champion, NGK, Bosch and Denso. These plugs are available at most aftermarket parts stores so there is no reason to put anything else into your car. The claims made by some parts companies regarding some special design that is supposed to give you more power, or better fuel economy don’t hold up. If you have modified your ignition system in same way then maybe you need something special but for the average car, stick with what it’s supposed to have.

The Auto Rules