I’m going to tell you a little story about Champion spark plugs. I’ve told you guys stories about the 1970’s and how we street raced almost nightly. Well I had Champion plugs in my 340 that a local Mopar engine builder built for me. After I had 600 miles on a set of plugs I had to make a 3 mile drive to a hill that I still climb almost daily. I had to go down into Freeport and when I climbed the hill I had to lug it down in third gear and jump on it. Boom boom it would backfire twice every day I did it then it was race ready. Well I asked the engine builder and he asked Champion spark plugs. Yep. Well throw them away and get Autolite plugs and gap them at .028. It never backfired again. Hmmmm