Why gap when using a pulley
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Joined: Mar 2005
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From: Enfield, CT






I recently had a few questions sent to me and wanted to get this out to gather as much information and knowledge for the person. Please correct me as needed.
When changing pulley size the gap of the plugs is frequently looked at to reduce heat. The heat is caused by added pressure in the cylinders from the higher boost. The heat can cause predetonation and this predetonation causes the knock sensor to trigger the computer to retard the timing which is known as Knock Retard or KR.
Therefore a cooler range of plug and gapping reduces the amount of heat and keeps KR from occuring allowing the maximum timing and power from the motor.
When changing pulley size the gap of the plugs is frequently looked at to reduce heat. The heat is caused by added pressure in the cylinders from the higher boost. The heat can cause predetonation and this predetonation causes the knock sensor to trigger the computer to retard the timing which is known as Knock Retard or KR.
Therefore a cooler range of plug and gapping reduces the amount of heat and keeps KR from occuring allowing the maximum timing and power from the motor.
http://www.centuryperformance.com/spark.asp
Something many do not know, is that with Higher Compression ratios and Superchargers as well as Nitrous, in many cases smaller spark plug gaps must be used as well as the use of a much hotter ignition system (see above). These higher cylinder pressures require more energy to jump the spark plug gap.
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musclecar6941
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