Common spark plug sizes to try getting several old outboards to start?

[softdown]

I am looking for a couple models that might be close enough to see if old outboards want to start. I have ten outboards that have not started in a long time. I'm sure that some are toast, they were bought to play with. Sometimes a guy gets lucky.

If a motor is healthy enough to run for a minute, then I will buy the exact plug that is recommended.

With a bad habit of letting toys sit for years, I have found that new plugs are almost magic for getting old parked motors to start. Perhaps because initial efforts kind of coats the old plugs with oils?

 

[Chris1956]

Most old Mercs use gapless plugs such as NGK BUHW. However, gapped plugs will work for testing. Make sure the reach is correct and pick a common plug.

 

[softdown]

Most old Mercs use gapless plugs such as NGK BUHW. However, gapped plugs will work for testing. Make sure the reach is correct and pick a common plug.

Thanks...can someone suggest a couple of the most common plugs? I seem to recall plugs being differentiated by heat range and resistance to "electrical interference"

Thinking that I should take pictures of my assortment of 10 outboards from 5hp to 175hp. Perhaps a kind wizard will suggest a few plugs, ideas, manuals,or whatnot.

 

[jimmbo]

There's a treasure of info on this site

http://www.boatinfo.no/lib/library.html#

 

[softdown]

There's a treasure of info on this site

http://www.boatinfo.no/lib/library.html#

Thanks.....I can no find no Merc info over 15 HP. Perhaps my 'puter lacks something needed.

 

[GA_Boater]

Can you list the motors?

 

[softdown]

Can you list the motors?

40 Mercury Mark 55E
175 Johnson
10 Johnson
5 Johnson
Recently aquired: 1 ea. Johnson 40 HP manual tilt,

electric & pull start, tiller or remote steering, Includes

1 parts motor

PROJECT MOTORS:

1 ea. Yamaha 50 HP

1 ea. Mercury 65 HP

1 ea. Mariner 30 HP

1 ea. Evinrude Triumph 55 HP

1 ea. Johnson Sea Horse 40 HP

 

[Chinewalker]

The Mark 55 - DO NOT put a long reach plug in there! Champion J6C is what the doc ordered...
If fthe Johnson 5 & 10 are 1950s-60s vintage, they'll also be happy with the J6C, as will the Johnson Sea Horse 40 if it falls into that vintage.
The book on the Evinrude 55 3-cylinder is a Champion L-19V.

The other motors in your list will need more info to narrow them down. Big plug difference between a 1978 Johnson 175 and a 1990s era 175. If you stick a long reach plug in a motor that needs shorter reach, you can damage the pistons...

 

[softdown]

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It would not load the third pic so I'll do it this way....two at a time.

 

[softdown]

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[softdown]

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Does storing outboards on their side or upside down hurt them? They are pretty stable when upside down... The 65 Merc. is kind of unmanageable with one guy. Well...so is the Yamaha.
Just got these babies.....then the snow started flying.

 

[merc850]

I would take the cowling off each one and see which plug(s) are installed.

 

[ondarvr]

The only thing you need to to worry about is the reach/thread length of the plug, for starting purposes heat range is irrelevant.