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1967 Mercury 500 50hp No Spark

J

jcohen9999

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I don’t know much about this engine so bear with me if I leave out any vital details.

1967 Mercury 500 50hp S/N 214122

Anyway as the title say there is no spark at the plugs from this recently acquired engine. I do know it sat in a warehouse for the last 7 years and before that it was a WI freshwater boat.

My first thought was to check the run/stop switch but that was disconnected already. The second is to check the distributor cap and magneto for corrosion but I am having trouble figuring out the best way to access the cap and magneto cover.

Access from the bottom is extremely limited and I’m not sure how to tackle it from the top.

Any guidance would be appreciated.


Pictures: https://share.icloud.com/photos/0726rVGtnD6xhTbvq3jaZztig
 
Simple.----There are 4 screws that allow you to remove bottom part of magneto.----And before you ask there is no need to worry about timing when you do that.
 
are you talking about these screws?

1704812504500.png

Because they are seemingly impossible to get at all of them...should I need to remove the carbs? or am i missing something simple?

TIA
Jeff
 
Be careful removing the rotor use 2 screwdrivers at 180* on either side: and don't spin the magneto while holding it it has a real kick!
 
So I finally got the distributor out. Should this points throw a spark if I spin the shaft? Is this a valid test? If not how can I test which part has failed?
Any any help for the next steps would be appreciated.

TIA
Jeff
 

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The spark should jump from the copper strip to ground (casing) - be careful it's strong if working properly. A small spark should jump across the points.
 
The spark should jump from the copper strip to ground (casing) - be careful it's strong if working properly. A small spark should jump across the points. Clean the points with emery cloth and contact cleaner then set them at .008*
 
I must be missing something. I replaced the condenser and the coil and I’m spitting the shaft and I don’t see any sparks at all. I even tried chucking it into a drill and spinning it faster than I could by hand.

Would appreciate any ideas on how to troubleshoot this.
 
You have to set the points at.008" on the high lobe of the cam (use a small amount of all purpose grease on the points shaft) and make sure they're clean.
 
They are gapped properly (I think). I did hit them with a little 1200 sandpaper in-situ as they already looked pretty clean but I will double check that that didn't change them.

What would be me next step(s)?
 
Away from the coil (CCW), the points have to be grease free; where did you get the new coil and condenser and why did you replace them?
Check that all the wires from the points etc. are not grounding to the base.
 
Quicksilver said:
Away from the coil (CCW), the points have to be grease free; where did you get the new coil and condenser and why did you replace them?
Check that all the wires from the points etc. are not grounding to the base.
Click to expand...
Points are clean.

There was no spark at the plugs so I decided to replace the coil and condensor. Both were supposedly NOS and came in what looked like unopened packaging but I know that doesn’t mean they are functional. Is there a way to test them?

Nothing is grounded to the case except the points themselves and the one side of the coil.

What I have now.
 
Quicksilver said:
All I can see from the pic. is the wire from coil to points is contacting the spring it should be isolated electrically.
Click to expand...
There was a gap but it goes to a screw that does seem to ground to the spring.

I put it back the way it was but then again it wasn’t working when I got it.

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