my buddy Ronnie had a '63 Dodge Super Stocker - aluminum front end and all the SS goodies. Engine was a 426 wedge with 13.5 : 1 compression, two staggered Carter 3447 four barrels, Dougers by Head, etc.
The Champion salesman who frequented the shop where Ronnie worked convinced him to try a set of Champions to see if they would work better than the Autolites Ronnie was using. We took the car to Aquasco drag strip in southern Maryland, installed the Champions and made two runs. The engine ran crappy on the first run and crappier on the second run. Ronnie re-installed the old Autolites which had at least a dozen runs on them. Engine ran great. I have run Autolites ever since. . .
OH...... yeah Rip. There's your regular, everyday driver. 
Bad example.
Most folks who have ever been around a Max Wedge, or a street/race Hemi, know that a simple spark plug change from heat range to heat range, or brand to brand know there's more to it than just the plug change. Think carb adjustment, valve timing and valve lash adjustments. That's why some ran better than others. 
[/QUOTE]
I dropped the modern Champions last summer, having scored some NOS J-11Y plugs absurdly cheap. Ran a little hot for my liking, so I scored J-13s for WAY LESS, (nobody wants these?) this past February, which are specified in the FSM, and sure enough, NO MORE PINGING AT SPEC ADVANCE 12.5 DEGREES!!!
I ran Autolite 85s a couple times a few yrs back. They did pretty much the same as the Champion J12YCs from Rock Auto, requiring me to retard the advance down to about 10 degrees to avoid pre-ignition pings.
I suspect adhering to Mopar specs as closely as possible might be the best thing to do. IFF I was running a big 4 barrel carb, with a "fat" cam, bigger valves, headers, and cooling system to match, then I suspect the old J-10s specified for cop cars, cabs, ambulances and such would be the thing. OR, equivalent plugs from other makers. I've also run Bosch platinum plugs one year, before committing to Champion as my first choice. So long as I can get NOS J-13Ys for no more than it cost for new stuff, I'm gonna roll with that.
To be sure, while I praise the RELATIVE simplicity of these excellent old machines, they're still hardly simple. With use accumulates wear, and as these machines wear in, they run best with all parts in harmony with regular upkeep on whatever brand parts used to produce the desired output. Radical change from such parts will certainly strain systems previously worn according to other parts, fuels, oils, coolants and with such strain changes one should be doubly alert to failures and breakdowns.
