cehcivic15

i put in some ngk plugs last night that are a heat range of 4...i think stock is 6...could this be a bad thing for the motor? ngk range is 2-12 2 being hot and 12 being cold. just wondering because i thought i heard a slight knocking tonight when i pulled into the driveway. could be my imagination i guess

Duane_in_Japan

You have to read the plug to see how it is burning, a bright light and magnifying glass to see down inside, if its all white, its too hot. It also depends on how you drive, go slow will burn different than go fast. Tool around town during the week then race on the weekend, change plugs for the weekend. Pulling into the driveway and driving down the road is two different kinds of driving, you have to inspect the plugs after driving a certain way.

Race down the strip, keep foot on gas, kill engine, inspect plug.
Drive down the street, keep foot on gas, kill engine, inspect plug.
Putt around, let go to idle, park, kill engine, inspect plug.

Choose your heat range based on close inspection, dont go too hot (lean) or you will be buying more than colder plugs.