Spark Plug compatibility question

[huntandhook]

I have an older 3.5HP outboard, and the repair manual lists the spark plug as Champion H8J. The closest plug I could find is a J8C. Is this plug compatible? I know that the 8 refers to the heat range, but what does the H, J, and C stand for? Thanks for the help.

H&H

 

[F_R]

Re: Spark Plug compatibility question

H stands for the "reach" or thread length. It's longer than a J

The second J stands for a two-cycle plug. The side electrode extends only half way across the center electrode to help prevent wet fouling. You can file the electrode of one of the new ones if you want to.

The C stands for Copper. No big deal outside the marketing hype world.

 

[tashasdaddy]

Re: Spark Plug compatibility question

here is the replacement[

img]http://www.championsparkplugs.com/results_cross.asp?pid=H8J&x=61&y=14&seenCrossWarning=1[/img]

 

[F_R]

Re: Spark Plug compatibility question

Yeah, that sounds like something Champion would do. They are recomending a RH plug. That's a resistor plug, no good for most old outboards. I Wonder how many resistor plugs I've pulled out of outboards in my lifetime because they wouldn't run. Ar-r-r-g-h

 

[Paul Moir]

Re: Spark Plug compatibility question

Check out what their guide recommends for say a '62 40hp!

Champion H8C plugs are easily found and should be perfectly acceptable. If you want to turn it into a H8J, just file the ground electrode back until it only half-covers the centre electrode. But I doubt you'll notice any difference.

 

[jadoty]

Re: Spark Plug compatibility question

Not to throw the thread off track, FR, but what do you mean by resistor plugs are "no good for most old outboards"? Are you talking about regular resistor plugs as opposed to inductive resistors (Champion Q plugs)? I thought those were specifically recommended for CDI ignitions.