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Firing problems

J

Justinjones6381

Member
I have a John Deere 50 that?s a 1956 model. I have
recently rewired it, put new points and condenser,
rotor button, spark plug wires, and new spark plugs.
When I check the firing with my fire checker it?s not
a pretty blue spark. It?s an ugly red spark. What
should my next plan of attack be on getting pretty
blue spark.
 
Pop the distributor cap off, turn on the ignition switch, one click if it’s the factory switch, pull the big wire out of the distributor cap and hold the end of the wire close to metal while you open and close the points with a screwdriver, again with the switch on. You should get a good strong 3/8” to 1/2” snapping spark jumping out of the wire. If the points are already open, short out the moving point with the screwdriver and pull the screwdriver away quickly to make the spark.

Is the spark weak when you have to push the points open? If so, rotate the engine so the points are open, then short the points with the screwdriver. If the spark is now strong the points aren’t making good enough contact.

My description sounds long and complicated but it’s really simple to do. Just be sure you are grabbing the insulated screwdriver handle only while you do this. Just play around with it making it spark, you can’t damage anything.
 
Here is a link to one opinion on [i:654c4848f0]<a href="https://www.yourmechanic.com/article/how-to-test-a-spark-plug-ignition-coil-by-eduardo-ruelas">How to Test a Spark Plug Ignition Coil</a>[/i:654c4848f0].

Hope this helps.
 
The ohmmeter tests will tell if a coil is bad but not if it is good. When under load and warm both the primary and secondary windings can short to each other or the secondary can even internally arc to the case. A good coil should arc one quarter inch of spark from the coil secondary wire to ground. The same is true with testing a battery with a hydrometer which will tell if the battery is bad but not if it is good. Only a load test will do that.
 
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