champion/ngk number of spark plugs for Johnson 5.5 HP

[Knientje]

I am still having troubles with my engine that's from 1963, but I brought it to a mechanic now. But he asks what the number of the spark plugs is there should be in. I put in Champion J6C, but the mechanic says it has a weak spark, according to the original manual there shoul be in Champion J4J, AC-M42K or Auto-Lite A21X.<br />I am in the Netherlands and as far as I know the only brands of spark plugs that are easily available are Champion and NGK. So does anybody know the new numbers to replace the old J4J spark plugs with?

 

[rickdb1boat]

Re: champion/ngk number of spark plugs for Johnson 5.5 HP

Champion J6C is the recommended plug for your motor. Gap is .030.<br /><br /> web page

 

[JB]

Re: champion/ngk number of spark plugs for Johnson 5.5 HP

The 1963 Johnson 5.5hp CD-20 originally used Champion J4J, friend Wabbit. The modern equivalent is J4C.<br /><br />Using J6C plugs would do no harm, but if J4C are available I recommend them.<br /><br />Good luck.

 

[Paul Moir]

Re: champion/ngk number of spark plugs for Johnson 5.5 HP

Why does the SparkPlugChart, and my (Seloc) manual suggest J6J's for these (and same era 3hp) engines anyway? Are they just plain wrong?<br />I've got a '63 3hp here, and it says right on it J4J. The manual says J6J...?

 

[seahorse5]

Re: champion/ngk number of spark plugs for Johnson 5.5 HP

As a rule of thumb with small OMC outboards (early ones), the J6C sparkplug was used in motors without a thermostat and J4 plugs used with engines equipped with thermostats.

 

[Paul Moir]

Re: champion/ngk number of spark plugs for Johnson 5.5 HP

Thanks Middleground and seahorse. The fouling issue makes good sense to me. As for the cylinder temperature, I noticed all 1956 engines used the J6J and I guess that was before OMC started using thermostats in some of their outboards. The only exception to seahorse's rule I can think of is the 28hp, with an OMC (and Seloc) recommended J4J and no thermostat. Mind you, that's not an engine designed for trollers.

 

[rolmops]

Re: champion/ngk number of spark plugs for Johnson 5.5 HP

hallo.<br />Voor de 1963 5.5 model cd20 moet je de champion j6c gebruiken.Dit komt rechtstreeks uit de OMC specificaties voor de CD20.