I have an '87 Wrangler with a 4.2 straight six, 170,000 miles. I have done an MC2150 conversion (1.08), ignition computer bypass, ford large dizzy cap upgrade, new plug wires, and have installed an MSD 6A with MSD Blaster SS Coil. My spark plug gap is .45 with stock Champion RFN14LY plugs.
When the Jeep reaches operating temperature (oil at operating temp), I experience pinging especially in fourth gear under high throttle. I have set timing to the factory spec, but there is still pinging. I have read that when using the MSD box, it is recommended to run a one or two step colder spark plug. Does anyone know which Champion part number would achieve this? I was told to use the RC12LYC but I am not sure that is correct.
Any help would be greatly appreciated. P.S. What timing specification should I use for a setup like this?