I have a '69 A 108 van (technically an "A" body?). Anyway it's about the engine (225 slant six) I currently have the recommended plugs but when it gets to normal temperature it pings like crazy. I think I need cooler plugs but can't find part numbers for the various heat ranges. The ones installed now are champion N11Y. what cooler plugs are available and what brands ? This van tends to run hot anyway due to basic design flaws with the cooling system.Thanks for any advice.
