Spark Plug Recommendation

[skanders01]

I almost hate to post this question in that I would think it would have been historically discussed to the point that the turnip is out of blood; however, here again I can not find any threads when searching this site for a current replacement for the old J4J. Not sure it is me or the site search functionality (or lack thereof.) looking for support on tte site for help searching the site and that was a catch 22 exercise.

Champion’s current website part search for my FD-16’s and my CD-11’s feeds back Champion plug #841 (which I think is the same as their J8C.) Marine Engine’s site says #825 (which I think is the same as J4C.) Marine engine says their site’s parts explosions are the last updated info they have from Johnson (at least the chat person says so in essence.) She also quoted a Champion plug number differing from both of these that was a current Champion OEM replacement plug A "Q" something plug (lost the chat chain.) Confirmed with Champion that their web site selection app is up to date.

Sorry to have to ask the group again, but until I become a better search engineer I need to rely on my friends at AOMCI. Looking for a thread or other input.

Thanks to all,

Kyle Anderson
Trempeleau, WI
skanders@triwest.net
920-764-0501

[nj-boatbuilder57]

J8C sounds a bit hot to me. I’m thinking a J6J is what the OEM spec is (but I don’t have my book in front of me). Of course a J6J hasn’t been made in years. The difference between a J6C and a J6J is where the lateral electrode ends. A "J" ends midway over the center electrode while a "C" ends at the far edge of the center electrode.

I’ve been told many times that filing a "C" back to a "J" is a worthwhile thing to do, but I can’t say I’ve ever tried. Maybe this summer!

Still, "8" sounds too hot to me….

[twostroke]

I’ve always filed back the electrode on a "C" plug to mimic the old "J" plugs on old non CD ignition two strokes. I’ve always thought they started better, but that may well be wishful thinking on my part.

Jim

I say "pardon me" a lot. I had a 20H, then raced open mod sleds.

[skanders01]

http://www.marineengine.com/newparts/pa … OMC0437686

Here is the link to the OEM plug from my lost chat. In case link doesn’t work, Johnson/OMC/BRP 765853, Champion QQL87YC.

Kyle Anderson
Trempeleau, WI
skanders@triwest.net
920-764-0501

[chris-p]

For the 50s OMCs, almost always start with a J6C (J6J replacement)

The J8C is much too hot a plug for what you need.

It is possible you may want to step down to a J4C, if the J6C is running too hot or you do a lot of wide open throttle running. After a few outings, check it. Should be a light brown colour.

[RICHARD A. WHITE]

Yup J4C and it is available…..

http://www.richardsoutboardtools.com
classicomctools@gmail.com

[Mumbles]

When new, your ’54 CD-11 came with a J6-J while the ’62 FD-16 probably had a colder J4-J installed in it. The hotter running thermostat temperature controlled FD has much higher compression requiring the colder plug but as the motor loses compression over time, it may require a slightly hotter J6-J plug to help keep deposits from forming and maintaining performance. With todays clean burning TCW III oils, deposits are no longer the problem they once were so the J plugs with the shortened electrode are no longer required. The correct heat range can be determined by studying a new plug after using the motor for a short time for its intended purpose. Heavy loads such as WOT or water skiing will generally require a colder plug but trolling or slower speeds might require a slightly hotter plug. The color of the plugs tip will indicate which one to use.

The Champion J4-J’s cross over to the superior NGK B6S plugs while the J6-J’s can be replaced with B8S plugs. Happy motoring!

http://www.sparkplug-crossreference.com … AMP_PN/J6J

http://www.sparkplug-crossreference.com … AMP_PN/J4J

[jerry-ahrens]

I would not go with J8C plugs, as they are probably to hot. For me personally, I run J6C in my 35 Gale, 18 Johnson and so on. I got lucky at Tomahawk, and found some NOS J6J’s very cheap. I came home with a couple hand fulls!

[crosbyman]

from the bible

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[garry-in-michigan]

From 1949 . . . 😎

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