Spark Plug Guide
Research by amceaglenest member "Jurjen"
The Eagle runs best on simple plugs. Only disadvantage is that they wear out quickly (6000 mls) in combination with the high voltage ignition. I don't like plugs with multiple ground electrodes, because they cannot be adjusted. And last but not least, I like the ones that protrude into the combustion chamber better because I expect the flame front to be more even (less knocking and better MPG). Engines that are burning oil, are better off with plugs that have less protrusion See and read under tip protrusion:
Here we go:
Truckplugs Champion 4412 Some off roaders like the truckplugs best, but they are not being made any more.
Normal plugs Champion RC12ECC Autolite 985 NGK ZFR5N Denso QJ16HR-Q Bosch FR9HC+
Premium plugs Champion RC12PEC5 Autolite AP 985 Bosch FR9HP+
Don't use (or only in engines that burn oil, to prevent fouling up) Champion RFN14LY (this is the plug advised by AMC) NGK ZFR4-11 NGK ZFR5-11 NGK FR5-1
General data Thread 14mm Reach 3/4" (19mm) Hex 5/8" (16mm) extended projected tip