best spark plugs 1958 johnson

[toddinmi]

Does anyone have any thoughts on the best spark plugs for a 1958 Johnson 5.5 hp Seahorse? NGK has an option for "surface discharge" plugs......any thoughts on that?

Thanks!

 

[samo_ott]

Re: best spark plugs 1958 johnson

They were built and designed to use Champions. That's all I use. J4J's or 6J's.

 

[Vic.S]

Re: best spark plugs 1958 johnson

Back in 1958 the plug recommendation was not restricted to Champions.

The recommended plugs were

Champion J4J, Autolite A3X. or AC M44C

The currently recommended plugs are J6C although J4C would be the modern version of J4J

Sorry dont know what would be the modern versions of the A3X or M44C

The NGK equiv of J6C is B6S and of J4C B7S.

 

[F_R]

Re: best spark plugs 1958 johnson

Surface gap plugs in a 5.5hp??? Aw, come on now. They need electronic ignition to fire them. And even then they don't work half the time.

Did NKG actually recommend them? I thought they might know better.

 

[toddinmi]

Re: best spark plugs 1958 johnson

NGK's website does show them for a 1958 5.5hp.......that's why I was asking......didn't seem right to me.

 

[F_R]

Re: best spark plugs 1958 johnson

They require a high voltage and very fast spark. Something the CD electronic ignition produces. But not the fat zap that is produced by the magneto, 1958 vintage. A magneto will produce a 1/4" spark if in good condition. The CD will produce a half inch with ease. Actually, I've seen them do an inch spark, but that's kind of rough on the coils to challenge them to do that.