1974 Evinrude 9.9 mag plate issues problems with excessive play

[utu586]

Hello-

I'm new to this site but it seems like a lot of skilled knowledge out there.....

I have a 1974 Evinrude 9.9 (Model 10454G) electric/sport twin outboard. The motor runs fine at low RPM but is badly misfiring now at higher RPM and starting to foul plugs. In trying to track down the issue I have noticed the mag plate appears to have a lot of "slop" and lifting up when the flywheel turns. I assume this causing the timing to be off causing my issue....My question is; is there any tricks to steady up the play? I notice the bronze/brass bushing on the inside of the mag plate looks like it cannot be replaced (mag plates are expensive and rare for this motor, not to mention buying a vintage may have the same issue). Any suggestions to help out would be greatly appreciated (more details the better).... Thanks!

 

[Daviet]

Re: 1974 Evinrude 9.9 mag plate issues problems with excessive play

Welcome to the forum.
I think Joe Reeves has a way of fixing them by dimpling the brass ring. Maybe he will chime in or you can PM him for the info.

 

[kbait]

Re: 1974 Evinrude 9.9 mag plate issues problems with excessive play

There's a plastic support ring that helps support the armature plate. I have used a length of thin wire w/plastic casing (one of the 3 in a phone cord), and placed the wire in the slot of that support ring and then install. It changes the effective outer diameter of that support ring, and helps hold it in place w/no lateral play. You'll have to trial/error it so it's not too tight or too loose by heating/stretching the wire's plastic coating to make it thinner, etc. PS.. support ring is NOT lubed, so remove any grease/oil before assembling.
Good luck!

 

[utu586]

Re: 1974 Evinrude 9.9 mag plate issues problems with excessive play

I'll give it a shot and post back when I get fixed...Thanks for the advice guys.

 

[F_R]

Re: 1974 Evinrude 9.9 mag plate issues problems with excessive play

Sorry to inject negativity in here, but just so you know, that model had MUCH trouble with fouling plugs and resulting poor running. The sloppy armature plate was just one of the causes. OMC came out with several kits to fix the problem, none of which worked. After a couple of years, they went to CDI ignition and the motors were much better.

 

[boobie]

Re: 1974 Evinrude 9.9 mag plate issues problems with excessive play

More negativity, JMHO but that ignition system on that mtr sucked. I've worked on a lot of them and always had nothing but probs. CDI ignition was the best thing OMC did to get rid of it.

 

[nwcove]

Re: 1974 Evinrude 9.9 mag plate issues problems with excessive play

universal ignition?.....or was it a hybrid?

 

[utu586]

Re: 1974 Evinrude 9.9 mag plate issues problems with excessive play

standard points contact/condenser magneto system....

 

[utu586]

Re: 1974 Evinrude 9.9 mag plate issues problems with excessive play

Welcome to the forum.
I think Joe Reeves has a way of fixing them by dimpling the brass ring. Maybe he will chime in or you can PM him for the info.

Thanks guys!...This worked quite well, tight as new, also used some lead tape (I use on golf clubs) on the mag plate bearing support to take up the slack there...

 

[utu586]

Re: 1974 Evinrude 9.9 mag plate issues problems with excessive play

Its ran for 39 years and still has 110 psi, I guess some issue can be expected after that length of time, plus its all i have right now...

 

[kbait]

Re: 1974 Evinrude 9.9 mag plate issues problems with excessive play

Should work fine now that the lateral play is gone. I've had good results using NGK B7HS @ .030" on those, replacing the Champion UL81C's.. likely won't matter now that you've shored up the arm.plate, but get the NGK's if you're buying new plugs for it.

 

[utu586]

Re: 1974 Evinrude 9.9 mag plate issues problems with excessive play

More negativity, JMHO but that ignition system on that mtr sucked. I've worked on a lot of them and always had nothing but probs. CDI ignition was the best thing OMC did to get rid of it.

I've heard its possible to convert it over to CDI, maybe I'll look into that later if the cost is effective enough...