j4c vs. j8c ??

[royal0014]

Ok, so call me late to the game. Have a Johnson RK-28B 40 hp Electramatic (1966). While perusing the parts manuel this morning, I discovered my engine calls for Champion J4C sparkplugs. When I got the motor it had, and still has, J8C plugs in it. I have had the motor running fine w/the 8's (in a drum, have not been on the water yet, still lots of work to do). So what exactly the difference between the two?I always prefer to go original.

I searched the forums here for the topic and found nothing.

When I looked up J4C on this site, it gave me J8C's. Searching elsewhere found J4C's with an average price $2-2.50. Found one site listed at $1.51 each if I bought 8. If they are getting hard to find, maybe buy the 8 and put 'em up?

The only dumb question is the one you didn't ask, right? Thanks to all!!

 

[wilde1j]

Re: j4c vs. j8c ??

40 1960 - 1973 J4C .030"
is the correct plug for your motor. The difference is heat range, the J8C being a hotter plug. The only reason to consider a hotter plug is to reduce fouling if your use is almost 100% trolling, and then the J6C would be a better choice. I would stick with the recommended plug, which is available.