Champion stock is RC12LC4 projected nose
1 step colder is RC11LC4
2 steps colder is RC10LC4

Older 2nd gens used RC12YC with the standard nose
1 step colder is RC11YC
2 step colder is RC10YC

I use RC12YC as I like the standard plug since it was thought the longer nose may contribute to ping. You want a hot enough plug to avoid fouling as that just increases the chances of ping. For me, colder plugs sucked. I got less power and mileage and when I went back to stock, it pinged again as it had built up carbon. Also didn't like Autolites. Champion is OEM so that's what I use.

 

Okay I’ll kept that In mind for my next Tune up!

Fyi for anyone following this page, my pinging is almost gone, I put about 4 tanks of 89 and drove straight 220 miles to go the desert for the day and back and I don’t anything pinging as much. It’s very very slight now. Not to sure what helped but sea foam or 89 helped. I believe it is 89 fuel helped a lot

 

I fix the problem %95! I was thinking hard over the weekend on what the sound could possibly be. So double checked all header bolts, check spark plugs, check plenum for oil. Check everything. Ended up being with the header connects to exhaust pipe. It was a little lose and needed to be tighten up. Tighten her up and started her up this morning and no more ping!!! Only “ping” I hear is my vavles ticking. There not load at all. I have to force on the sound to hear it.

thank you all for the help!

 

My pinging is still there a little bit. I had a bad plenum gasket. For the second time I decided to buy the Hughes install for a good amount of money. Only good thing is that. No more plenum leaking!