318 MAX fuel economy builds?

AJ/FormS said

Champion 12s, with the 5/8s hex for plug clearance
maybe RJ12YC, or something like that. I mean, I've only seen them 3 times since 1999, lol.

Click to expand...

RC12YC is the 3/4 reach, 5/8 hex plug.

The “C” denotes that.

The “J” series plugs are 5/8 reach, 13/16 hex plugs. They used those junkers in big block Chryslers.