Good Spark Plug Description Guide

[john f2000]

Although this is for motorcycles the page is a good description on how to read plugs. Click on some of the links they are preety good.
http://www.dansmc.com/sparkplugs1.htm

[Lavey Huffer]

here's another one I've delt with this guy and had very good results
http://www.4secondsflat.com/Spark_plug_reading.html