Sponsored Links (Register now to hide all advertisements)
I'm sure it's down to engine spec. H10's work great by most accounts on stock engines, a good number of modified flatheads however like a hotter plug it seems.
The NGK equivalent of the champion H10 will more often than not work great in the engines that will foul an H10 in short order, and would refuse to work after cleaning. The NGK equivalent stayed clean.
Why the NGK works better in this scenario, I don't know, but it does.
I can only guess that the NGK equivalent is actually a hotter plug than the H10.
This experience led me to believe that the H10 was a rubbish plug. I now sit here older, uglier but hopefully a bit wiser than I was. So my opinion has changed about the champion H10. It works great in a stock engine. If it's modified, you may need a hotter champion plug.
Martin.