15hp ignition conversion plug change

[johnyrude200]

So, today I ended up taking a ’76 powerhead and doing a conversion with transplanted ignition components to utilize CD ignition. Finishing up the job, I stopped and said, so which plugs are correct for this motor? I am assuming L77JC4’s go with CD ignition, while the older BR7HS (NGK) or L86 (champion) plugs stay with the low-tension magneto (barf).

I mean, a powerhead is a powerhead; the plugs change with the ignition….right?

[r-c]

The L77J’s are listed in the 1977 manual for the CD ignition.

[johnyrude200]

Yes, the year doesn’t matter, the ignition is what counts. Just wanted to verify since the ’74-’76 powerheads generally don’t get the upgrade from anyone outside of the club or a retired mechanic. They usually just get put in the dumpster due to all the engineering shortcomings across the board. ’76 is better, but not a far cry from the nightmare service updates earlier productions had applied to fix underlying issues.

[PugetSoundBoater]

I was told by a member that the NGK plugs to use on the low tension are B7HS not BR7HS. My ’76 9.9 had BR7HS in the motor when i bought it and it ran ok.I thought how weird,NGK’s in an Evinrude,i was expecting to see Champion’s. Now i use the B7HS.

"Some people want to know how a watch works, others just want to know what time it is"
Robbie Robertson

[joesnuffy]

I to use the NGKs B7HS in the 9.9s they seemed to do the best both on cd and points ignitions on the 9.9 motors I have worked on. I think the R is resistor if memory serves me correct not using the resistor worked better for me.

Joe

[outbdnut2]

When you upgrade to CD ignition, the NGK plug would be the BR9HS-10. The -10 is a plug made to have .040 gap rather than the same plug number without the -10,which is to be gapped at .030. Note that NGK heat ranges are hotter with a lower number after the BR. I’ve also found that some vendor websites disagree with each other on which heat range to use.

Below is one chart on which plug should go in the 9.9/15 Johnsons – note in 1980, the ignition was made more robust and the -10 plugs spec’d for the .040 gap – see below:

http://www.marineengine.com/parts/ngk/johnson.html

[outbdnut2]

quote pugetsoundboater:

I was told by a member that the NGK plugs to use on the low tension are B7HS not BR7HS. My ’76 9.9 had BR7HS in the motor when i bought it and it ran ok.I thought how weird,NGK’s in an Evinrude,i was expecting to see Champion’s. Now i use the B7HS.

I’ve found some 9.9s and 15s I’ve worked on for friends just don’t idle right for trolling with Champion plugs, and I’ve tried various heat ranges; but with NGKs they magically idle fine. I [posted here a couple years ago about that and several people agreed, but nobody knew why. I also have three 15s (1989 and 1991) that work just fine with Champions.
Dave

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