What is the spark plug gap?

The area on a spark plug where the spark takes place. Spark plug gap is the distance that energy must breech to complete an electrical circuit. It varies fron manufacturer to manufacturer but plug gap must be correct to within .003" to meet spec. Any plug that is out of spec. more than .003" should be replaced. Regular maintaince dictates this interval, any plug left too long during the course of service, that excedies OEM spec. can (and will) cause premature ignition system failure. The larger the spark jump the more energy required, the more energy required, more heat is produced. Car igition systems operate at 50,000 + volts. Thousands of an inch can leave you stranded. Most importantly, modern DIS (ignition) systems can cost hundereds of dollars to fix when pushed beyond intended threshold. GM Licensed Mechanic, Ryan