Projected Core Nose: This type sticks the spark 1/8" into the combustion chamber. This helps prevent low speed and cold fouling and also gets cooled by the incoming charge at high speed. It is difficult to build a projected plug in very cold heat ranges however, because of the long ground wire, which is typically the hottest part of the plug. To a very limited degree, this plug behaves as though the ignition were more advanced, because it places the flame more centrally in the chamber.