Butler Performance Inc. - Spark Plugs

Here is an example if you have a question about the heat range on an NGK spark plug.

The lower the #, the hotter the plug is.

(Example- -6 is a hotter plug than -9)

Spark plug gap for Points is .035 and any electronic or MSD is .040-.045

General Guideline- Pump gas street engines would use a -5 to -7 heat range, high compression race engines may use a -8 or -9 heat range, and boosted/nitrous engines may use a -9 or -10 heat range depending on levels of boost/nitrous.