2 duff champions on a service up in the valleys on a Saturday evening, 2 old ones went back in, never used them since
I stopped using champion in the 90s lots of misfiring on my Bonnie and Econoline 150, changed to NGK, problems solved.I had it in the 70s with Champion N9Ys. My high compression pre-crossflow 1500 Cortina would misbehave and misfire with them in. I changed to NGK and all was well again. I have not been a fan of Champion since.
I stopped using champion in the 90s lots of misfiring on my Bonnie and Econoline 150, changed to NGK, problems solved.
Norm.