Sp1 Indexing Washer Kit 3-cylinder 12/pk

Indexed spark plugs align the open end of the electrode toward the intake port. the hottest flame meets the new fuel charge for a performance gain, increases fuel mileage and plug life. this is a speed secret car racers have used for years. you simply mark the electrode side of the plug with a magic marker on the porcelain. you then shim the plugs with the washers to align the electrodes toward the intake ports. fits 14mm threaded spark plugs.