Why are there so many plug choices? What parameters are most important? For example, my trick flow heads call for auto lite 3924 plugs. But nowhere else do I find them for mopar big block. I saw
@AndyF recommend NGK plugs I think 6987. But they are not 440 either. Is it the heads, the block, the ignition, or what else? I have a efi sniper, 512 with hyper spark ignition and I have used the auto lites but wonder if they are correct for the application. Any guidance appreciated.