[Hib Halverson]

That story doesn't say much at all about how to select a heat range but what's there, if anything, confirms what I said earlier about plugs.

But...if the plug originally developed for the engine was an AC 1 heat range, unless the engine is in a trailer queen...why is everyone running such hot plugs?

Do they know more than the engineers who spent years testing plugs?

I'll stick with my Denso 22 heat range.

But I will grant you, for engines which see a lot of starts without warm-ups, are running too rich at idle and part throttle or are using oil, the cold plug is a mistake.