I am looking to change out my spark plugs in my 1991 YJ with a 4.7L Stroker.
I already tried running the Champion® Double Platinum - Spark Plugs Part Number: 7034 and found that they caused too rough of an idle. The Champion and Autolite Copper Core Plugs, both don't seem to burn right and cause an uneven idle, plus they cause a lot of back fire out the exhaust.
So I am thinking about trying the Autolite® XP Xtreme Performance® Iridium - Spark Plugs Part Number: XP985 since they do not require as much voltage as the double Platinum plugs do, but they still burn a little hotter and more efficient then copper core plugs.
Has anyone had any experience running the Autolite Iridium in their 4.0L H.O.? If so how did they do?
Thanks to anyone who can provide some insight.