proper spark plug for '68 20 hp Johnson

[Jake362]

I was wondering what spark plugs should be ran in a 1968 20 HP Johnson I recently purchased. The engine seems to be running fine on champion J6C plugs, but I just want to have extra plugs on hand. Does it take a champion J6C, J4C or a RJ12C? I checked the Champion Spark Plug sight and it says the J4C is the replacement for the J4J. Should I stick with the J6C or switch? Thanks

 

[JB]

Re: proper spark plug for '68 20 hp Johnson

If you do a lot of low speed operation and trolling stick with the J6C, Jake. The J4C would be better for extended high speed operation. RJ12C is too hot for that engine.<br /><br />Good luck, and welcome aboard.

 

[Jake362]

Re: proper spark plug for '68 20 hp Johnson

Thanks, That's the kind of answer I was looking for. Direct and to the point! <br /><br />Jake362