Topic: 1949 Johnson 10hp QD-10 igntion questions – Antique Outboard Motor Club,Inc

This topic has 10 replies, 5 voices, and was last updated 5 years, 8 months ago by parker.

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July 29, 2018 at 8:37 pm #10705
parker
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I’m new to working on vintage outboards and am just getting in to tinkering with a QD-10 that’s been sitting around for at least 25 years. I’ve got weak spark (enough to shock me but not enough to visualize) on the top cylinder and no spark on the bottom. Compression is good. The coils appear original so I’m guessing that’s part of my problem. Can someone point me in the direction towards upgrading the coils to using the later style that’s still available? I’ve read this is possible with a little fabrication but can’t find a DIY.

Through the port of the flywheel I can see the coils and the points. The points I see don’t match what’s in the parts catalog. Can anybody shed light on these in the attached image? Was going to check and see if I could clean the breaker but these look different than what I’m used to seeing. Part number 510054. Can’t find much information out there. Thank you in advance!
July 29, 2018 at 9:14 pm #80336
RICK EICHRODT
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US Member - 2 Years
It is my opinion that you may have good coils but dirty points and maybe faulty condensers. This ignition system has a magnet rotor that spins close to the coils, they face inward to the rotor. Meter the coil and read for secondary continuity. Go from spark plug wire to the ground on the coil and you should get an ohm reading. If you get an open reading, just like holding the two ends of your ohmmeter apart, then you have bad coils. If you do get a good reading, somewhere between 1000 and 5000 ohms, then the coils "should" be good. Clean the contacts of the points and install new condensers and then see what kind of spark you get. I am sure others will chime in with their opinions. Take your time and do some research!
July 30, 2018 at 2:50 am #80360
garry-in-michigan
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Lifetime Member
That was a standard magneto from 1947 through 1951. (OMC motors from 1946 were mostly left overs from 1942) The new magneto standard came with the 1951 on the Big Twin Evinrude & RD model Johnson. This was on the Gale products 5 horse . . .

and this on the Evinrude 3.3 horse Sportwin . . .

Make sure your breaker points are REALLY CLEAN . . . 😎

Your breaker base is different, but the layout of the insulators is the same. . .
July 30, 2018 at 2:57 pm #80388
frankr
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US Member - 1 Year (includes $3 online payment fee)
Actually, the QD-10 has the notorious 580040 coils that are notorious for being NG. And the breaker points are part # 580016.
July 30, 2018 at 3:01 pm #80389
frankr
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US Member - 1 Year (includes $3 online payment fee)
New coils and points are still available, but cost more than the whole motor is worth.
July 31, 2018 at 3:04 pm #80463
parker
Participant
Thank you for all of the info everyone! I’ll check the resistance on the coils and clean the contacts on the points. That breaker point assembly diagram really helps.
August 4, 2018 at 7:02 pm #80653
parker
Participant
Update:

Cleaned and adjusted the points. Getting great spark out of number 1! Still getting nothing out of the other spark plug. The resistance from the coil to the ignition wire on the non-firing plug tests as OL. On the firing one I get about .35 k ohms. So, it is looking like a bad coil from what I can see.

I’ll look around for a NOS coil however if there is a new replacement that I can modify I’d much prefer to go that route. Can someone let me know which one to get?
August 4, 2018 at 10:40 pm #80659
garry-in-michigan
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Lifetime Member
I understand the classic OMC coil may be used with the existing 580040 laminations and a little creative modification of the spark plug wire routing . . . 😎
August 12, 2018 at 9:43 pm #81032
parker
Participant
2nd Update

I’ve swapped the laminations from the old 580040 coils onto the new ones I purchased (18-5181). Here are the best directions I found on how to to the modifications to the coils and the mag plate underneath. http://www.mlaoc.ca/uploads/1/0/5/9/10597650/johnson_qd_coils.pdf

I’ll post more pictures when I pick up some replacement ignition wires. Right now I’m using the old ones and they can be routed better. But the best part is I now have spark on both cylinders! Going to have to pull the mag plate off again to secure the new wires so I haven’t tried running the motor yet.

View of mag plate with old coils:

Difference in coil laminations:

Comparison between new and old on mag plate

Mag plate with new coils

PDF

johnson_qd_coils.pdf
August 13, 2018 at 12:59 pm #81069
lindy46
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US Member - 1 Year (includes $3 online payment fee)
That should work. I had to do the same thing with my 1954 Majestic as the replacement coils were way too expensive – much more than the cost of the motor. Make sure to tuck in those coil wires so they don’t rub on the flywheel or cam/crankshaft.
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