Sparkplug Neptune 15B2

[Ronald Smith]

What plug does a Neptune 15B2 use?

[joecb]

Doing a little research in the “Old outboard Book” looks like your motor is a 2 Hp Muncie/ Neptune that uses a Champion 6M  Gap .025

superseded by a Champion K15J. That may still be an old number, but see where it leads you

Joe B

PS, really not critical , my $0.02 worth

[Ronald Smith]

Thanks. I cross referenced the K-15J to an Autolight. Got a Neptune 15B2 in a package deal for 3 motors. $40 each. Also an Evinrude 4407 Ranger and a Johnson TN27. All have spark and compression. So, I put a carb I kit in it. The cork was dry and pristine. So I gave to several coats of hot fuel dope. Cleaned the tank. Still trying to find a good way to do that. First acetone. Came out only slightly yellow with varnish. Then denatured alcohol with nuts. That really got a lot out. Then Rust-Oleum rust remover. Dilute phosphoric acid. My next tank will try muriatic acid. Now with your help and a plug, test fire. Will pull mag rotor and clean points if needed. Pictures later. Also ordered the Old Outboard. Thanks again.

[joecb]

While we are on the subject of spark plugs… you may or may not know that the “J” sufix on obsolete Champion plugs indicated a plug that has a shortened ground electrode, where the ground electrode only extends to the center of the positive electrode. These plugs were intended to minimize carbon deposit shorting across the gap. You can convert any Champion plug to a “J” by filing back the ground electrode. I have heard that the “J” had its origin as in,  Johnson Outboard Motors… perhaps.

Joe B

[stanley]

Well,Champion was making a”J63” plug in 1920,before Johnson started outboard production.It was a 18mm plug,semi aircraft style and was early motorcycle plug.The AC regular metric version was the Johnson factory installed plug in the early A models.

[joecb]

The “J” I was referring to is the sufix “J”… comes AFTER the plug number, as in K 15 J

Joe B

[stanley]

Joe,I apologize,I read right past the “suffix” in your comment.It is interesting that early on AC was Johnson factory plug and then about 1930 Champion took over.I wonder what the reason was for the switch.

[joecb]

I had heard that by the early thirties AC then a division of General Motors had all their production capacity dedicated to GM vehicle production. They weren’t messing around with other lines.  If true , makes sense.

Joe B

[stanley]

That does make does make sense.A great book that covers a lot of those early days of the auto industry is “Fast Times of Albert Champion”,founder of both Champion and AC.

[Author]

Posts