Home › Forum › Ask A Member › 1955 Johnson 10 HP QD-16, no Spark
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Mumbles.
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February 7, 2022 at 2:23 am #254177
Good evening to everyone!
First, thank you to all of those members who took time to respond to my last inquiry about the Johnson TD-20 I am working on. I have another question for everyone. I am working on a 1955 Johnson 10 HP QD-16, I have replaced everything on the armature plate (points, coils, and condensers), put the flywheel back on, replaced the spark plug wires, installed new spark plugs, took off and replaced the fuel and air lines, cleaned the carb and installed new parts where need be, and I have changed out the water impeller in the lower unit. When I took it to the tank to start it up, granted it was the first time in probably 30 years this engine has been in water but everything is new to the best of my abilities, I pulled on the cord and pulled, and pulled. I then checked the spark on the new wires and… no spark on either cylinder. I have some literature coming in the mail soon, an assortment of books and manuals from the era, that I am hoping will help me to diagnose the problem I am having. In the interim, I would like to tap into the wealth of knowledge here in the club and ask if anyone has any advice and could help me trouble shoot my problem about why I don’t have spark on either cylinder? I gaped the points to .020, I have grounded all the wires, but I have not checked the distance between the coils and the flywheel… this might be my problem? The coils are not touching the flywheel, but maybe there is a specific gap I need to set between the coils and the flywheel? Just brainstorming here…
All the best!
ChadFebruary 7, 2022 at 4:42 am #254178Are you sure you got the coils wired up to the correct set of points?
February 7, 2022 at 7:30 am #254180check tto see if the points are making GOOD contact.
February 7, 2022 at 7:45 am #254181did you download the RED book ?? it is what you need to service your Oldy
did you measure the secondary resistance from the the plug boot end to the engine frame (post your results !)
did you adjust the timing as per the attached link
http://www.youtube.com/watch?v=ga1Cjymj6ms&feature=youtu.be
did you polish up the points and cleaned them with carb cleaner or acetone soaked in a business card or eqv. ?
Joining AOMCI has priviledges 🙂
February 7, 2022 at 6:11 pm #254228Also make sure the points cam is installed right side up with the word ‘TOP’ on it facing up.
February 10, 2022 at 10:21 am #254355New points must be CLEANED!
February 11, 2022 at 9:16 pm #254445Clean the points.
February 12, 2022 at 9:59 am #254473All good suggestions. And yes, there is a specific “air gap” that the coils must be set to. There is a special tool/ring to set this air gap, but I’m sure you don’t have that. So, it is usually “close enough” to line up the coil laminations with the machined marks just below the coil laminations on the mag plate. The coil laminations will hit the flywheel and cause damage if the coils are set out too far, and the magnetic fields won’t be strong enough to produce proper voltage if the coils are set out too far from the flywheel magnets.
These engines are a bit of a challenge to set point gap with the crazy spring/seal set up under the point cam. You must be very careful when reinstalling the flywheel, oftentimes the cam will come down on top of one/both of the point arm rubbing blocks, forcing it down can damage the points. Once the flywheel is installed and snugged down slightly, you could always recheck point gap by removing the flywheel cover and checking the gaps when the open flywheel window is over each set of points. This brings me to another possible issue. Improper flywheel torquing could have led to the flywheel key shearing when you tried to start the engine. Once the flywheel key is sheared, even slightly, you will have no spark on either cylinder.
And like Mumbles pointed out, it is easy to connect the coil primary leads to the wrong set of points, which would lead to no spark also. And yes, new points need to be cleaned, there may be a slight coating on them which is enough to cause an issue.
February 12, 2022 at 1:03 pm #254491Setting the points is easy if you first remove the spring under the cam and then place the cam back on the crank. When it comes time to put the flywheel back on, reinstall the spring and the cam with the word ‘TOP’ facing up. Then the crank must be rotated so the high point of the cam is centred between the rubbing blocks of the points. Make sure the cam is clear of the rubbing blocks by first pushing it down with your fingers before installing the flywheel. Failure to do this can or will result in damaged points.
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