ONE OF THE BEST WAYS TO INITIATE an animated discussion with car guys is to offer an opinion about spark plugs. Everyone has their own point of view, and there’s always plenty to talk about. Because of the wild claims about spark plugs adding horsepower and other magical achievements, we thought we’d take a look at the host of variables that are involved with selecting the best spark plug for your application.
The best place to begin is with some operational basics. It all starts with ensuring that the spark plug properly fits its intended application. For stock vehicles, this is as easy as looking it up in a parts catalog. But if your engine is well beyond what the factory intended, or parts have been swapped around, then there are some important decisions to be made.
IDENTIFYING YOUR PLUGS
The first items to determine should be the thread pitch and length of the spark plug along with the sealing method. Most OE spark plugs from the last 40 years have
