Spark Plug Heat Range

10-4 Fishy (Pardon the 70's CB reference, lol!). All Autolite really gives you is the 100 hp "Rule Of Thumb". I'll keep Googling to see what I can come up with. I'm sure that the pro drag and road race guys have found some answers but they make their living with this knowledge and I don't blame them for not sharing.

BTW, I have not installed the cooler plugs yet due to the heat caused carb boiling problem. One change at a time, right? LOL!

As Hot Rodders we are all in essence mad scientists treading where the OEM's don't go or won't tell us what they know. These engines were never designed to produce the HP that we're pushing them to, but damn, it is fun! lol! Unless we're running NASCAR or maybe the new Challenger Drag Pack, they are not going to give us the info we need, so it's up to us to gather data through empirical experience and share with out Mopar Bretheren.

That 100 hp rule is interesting. That's the first time I'd heard of that. If that's the case I probably have the right plugs in my 360 since I have 68 340 heads and run one step colder than stock 340's ran and my engine is about 80-85 hp more than they were stock.

That's funny about us being "Mad Scientists" cause when I first got Desktop Dyno I was constantly playing with it and my wife called me a "Mad Scientist" because of it.