Spark plugs?

[jessyj]

I have a 96 with the 5.9 magnum it uses champion rc12yc plugs. Just got a 98 with 5.9 magnum, it uses champion rc12lc4 plugs. The 98 plugs are a little longer around the electrode, meaning they protrude into the cylinder a bit more. I wonder if the 98 plugs can be used in the 96 or would there be problems like hitting the piston.It just seems odd as to why dodge did this, maybe it was for fuel economy. Whats all your thoughts on this. Thanks and happy motoring.

 

[dodge dude94]

The RC12LC4 plug is merely an emissions plug. They'll interchange just fine. Most guys run the earlier spec'd plugs in all Magnums because they cut down on spark knock.

 

[AK12MN]

I run Autolite 3923 for a cooler plug.

 

[Yeret]

Back when my plenum was leaking, the Autolite 3923 plugs did slightly help with knocking. When I had the Hughes kit swapped on, I went back to the Champion RC12YC and had no problems. I've since switched to NGK BKR6E V-Power, mainly because this is the plug that Flyin' Ryan, who wrote the tune for my engine, recommends.