Spark plug resistance testers

May 31, 2012

The Tempest AT5K resistance tester is a very efficient and effect means to test the internal resistance in all aviation spark plugs. Simply place the spark plug, barrel side down, over the contact post and touch the other lead end to the firing end of the center electrode. If the light is green, the spark plug resistance is below 4kΩ (thousand ohms). If both the green and red lights are on, then the plug is between 4-5kΩ. This is acceptable for serviceable plugs. If only the red light is on, this indicates a resistance value in excess of 5kΩ and the plug should be discarded and replaced. For more information, visit www.tempestplus.com.