John, do you think a Champion c63cx would be too hot a plug to run on the street? I will be using GT100 unleaded gas with a dose of VP110. 427/435 w/hydraulic roller. 11.5:1. Thanks

 

I'm not familiar with that plug; stock L-71's run fine with AC R45XLS plugs. PAMotorman may have a suggestion.

 

The Champion 63 is a warmer plug, but as John suggested the R45XLS heat range is good for most BB engines including the L88`s. You could also use 44`s as long as its a tight sealing engine with correctly jetted carburetors so they wont fuel foul from idling....All that's necessary is to use what John recommended for your best performance...

 

Thanks guys, I had a set of these c63cx's laying around and I wanted to test fire the motor. I can't seem to find a good cross reference from AC to Champion. I guess I'll order up a set of c61cx's for the actual driving.

 

JohnZ's recommendation for AC R45XLS spark plugs crosses over to Champion RN14YC.

Larry