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!965 Mercury Model 60 6 HP - Weak Spark on Top, No Spark on Bottom

J

JeffinColorado

New member
My initial phase of getting the engine running found the top spark plug was a weak spark and the bottom plug with no spark.

The points are in good shape so I filed them flat and set the gap to 0.20.

The plugs are new: Champion J8C Gap set at 0.025 (Clean and dry)

I tested the condensers, then switched their position with no changes in the spark.

The coil primary winding has less than 1 ohm resistance. The secondary coils are (Top) 6.66K and (Bottom 6.59K)

The spark plug wires are okay as best, but not burned or shorted to ground.

The point cam is in the correct orientation with the word "TOP" on top.

I'm starting to think, water, oil, grease may be shorting the system somewhere.


Any advice would be appreciated.
 
That should be good. Continuity good through the plug wires....copper core? Some people replace the wires with the wrong type. Does it look all original?
 
Sorry----The term " weak spark " means nothing.-----Post the results of a proper test.-----Does spark on your leads jump a gap of 1/16" or 1/8" or say 5/16".----Answering that will get you some results on what to check next.
 
Over the last few days I have disassembled and cleaned the entire ignition plate assembly. On the back-side of the kill switch wire that leads to the bottom breaker-point connection, I found a crack that could have been the cause of the no spark condition.

I repaired the crack with heat-shrink, afterwhich there is now spark to both the top and bottom.

I am still concerned over the intensity of the spark. I've opened the gap up to 1/8 inch and will intermittently get a spark. This may be simply due to the age of the components or the low speed that I'm turning the engine as the 1965 model does not allow the use of a pull start with the cover off.

I'm going to move on the the fuel system next and once that is check out, I'll go for a start.

Thanks to everyone for the advice
 
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