Johnson QD 10 Magneto Swap

[bayham3261]

I have a really nice 1950 QD10 that I bought last summer from the original owner’s son. Like most finds it hadn’t run in 30+yrs and after a complete go-thru (carb clean /seals, fuel line cleaning, fuel filter seal, new plugs, points reset, crank seals, impeller and gearcase seals)it started up on the 2nd pull. After running amazing in a test tank for 10-15 minutes the magneto seems to be failing. I have a donor QD13 with the OMC universal magneto setup. Has anyone done a similar magneto swap on an early QD? Any issues to look for? I assume I will swap the complete magneto plate… would the flywheel need to swapped too? I suspect the points cam may not be compatible.
Thanks!

A little information is a dangerous thing!

• This topic was modified 5 years, 3 months ago by bayham3261.
• This topic was modified 5 years, 3 months ago by bayham3261.

[Mumbles]

Heck, those hard to find (as in expensive) coils look to be in good shape. No leaks or visible cracks on them. I’d check these ones first with an ohmmeter and also clean and polish the points and all contact surfaces of the brass mounting pieces. Chances are the caps (condensers) are going south too and should be replaced. While you are in there, new spark plug wires might be needed to along with a fresh set of NGK plugs.

As a motor warms up, the heat does funny things to the electrical components. The coils start to fail along with caps etc. A good ignition tuneup might solve your issues.

[bayham3261]

Thanks Mumbles,

The coils do look good and that’s why didn’t do anything to them initially (forgot to mention that I soldered on 2 new sparkplug wires.) They had dripped a bit but not too bad. The coating is generally good. I was thinking of getter creative with them by sealing them with Plasti-dip to prevent future drips. Not sure if that would work.

I’ll have a closer look at the condensers.

My plan is to run the outboard at the family cottage for a couple weeks this summer so I was looking for reasonable reliability.

A little information is a dangerous thing!

[frankr]

I was in agreement that the coils look pretty good, till you said they dripped. That is a sure clue that they are on their way out.

However, as well as I can see from the picture, those points don’t look too well. I’d suggest some conservative action before going for the coils. Take the points completely apart and degrease everything, then polish each contact individually. Reassemble and set gaps to 0.020″.

If it still gives trouble when warmed up. I’m afraid it probably is coils.

[2fast4me]

I looked at doing the same thing with an ELTO 12HP I have that had a broken flywheel. I never went ahead with the conversion to a later OMC ignition/magneto plate/flywheel combination. When i was evaluating it everything looked like it would fit but that is where i stopped. I found a flywheel from a QD10 that was the same P/N so that is what is installed now and works. Sorry but I’m not much help.
Jim

2Fast4Me

[The Boat House]

• This reply was modified 5 years, 3 months ago by The Boat House.
• This reply was modified 5 years, 3 months ago by The Boat House.
• This reply was modified 3 years, 2 months ago by The Boat House.

[seakaye12]

Hi ,Using your existing mag plate and all the other components now mounted on it (points, condensors etc) you can retro-mount the current style universal OMC coils….but you have to get a bit creative with the spark plug wiring as the new style coils cannot be positioned in the same manner as the original ones. The spark plug wires will either exit out the top or the bottom….and you have to route them in a way where nothing shorts to ground or gets rubbed by the flywheel. It is doable. There are a few threads here along with pictures. The one I can find right now is: https://aomci.org/forums/topic/1949-johnson-10hp-qd-10-igntion-questions/

• This reply was modified 5 years, 3 months ago by seakaye12.
• This reply was modified 5 years, 3 months ago by seakaye12.

[bayham3261]

Thanks everyone! I’m going to try a retro fit of new coils on the old plate. It would be nice to keep everything as close to original as possible.

A little information is a dangerous thing!

[RICHARD A. WHITE]

Original is nice, but remember this, when showing off at the dock, on how well your motor will perform, it is highly unlikely that ANYONE will demand you remove the flywheel to confirm the originality of the coils…LOL

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

[20mercman]

I used the new OMC coils on our 1950 Fleetwin that had the magneto you have. On mine, it had the usual melted coils, but in any event, the swap worked just fine. Slipped the coils off of the laminations, and on to the original ones. Worked great!

Steve

[Author]

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