23 To find the cause of no spark work through my Troubleshooting Procedure linked below, heres a start:
NOTE The coils output terminal (to distributor not from switch) is wired to the points and when closed they short out the coil output to ground so it conducts current. That should ONLY happen when good working points are CLOSED but when NOT (points open) there would be approximate battery voltage on the coils output HOWEVER if there's a short (see below or coils LV primary were bad/open) you wouldn't read voltage there. If its always zero there (should only be when points are closed) there's a short, see below:
1) COILS "INPUT" VOLTAGE (wire from Ignition switch)
If the ignition is ON and all is okay ?? there would be approximate battery voltage on the coils small input terminal.
2) COILS "OUTPUT" VOLTAGE (wire/terminal from coil to distributor)
a) IF POINTS CLOSED (as normally are engine not running) there should be near zero volts (IE there's a short circuit to ground)
b) IF POINTS OPEN there should be approximately battery voltage
3) If you turn on the ignition and crank the engine over with a test lamp on the coils output (to distributor) it should flash ON (when points open) and OFF (when points closed)
4) Ifffffffff with ign on and working the voltage on the coils output to distributor terminal is ALWAYS NEAR ZERO (should ONLY be when points closed) there's a closed circuit/short such as:
a) Distributors side pass through insulated terminal (where wire from coil attaches) is shorted out (seen it happen) an ohm meter or continuity tester can find that
b) Points are NOT opening (closed shut) see if they open and close when dist turns??
c) Points (sometimes spring) are shorted out
d) Condensor (or its wire) is shorted out
Check the wiring and especially the dist side pass through insulator terminal for a short,,,,,,,,,,,insure condensor wire isnt shorted to case,,,,,,,,,,,,,,,,,,,,insure condensor isnt bad/shorted,,,,,,,,,,,insure points open and close,,,,,,,,,,,,,insure points arent shorted out
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Today's Featured Article - Timing Your Magneto Ignition Tractor - by Chris Pratt. If you have done major engine work or restored your tractor, chances are you removed the magneto and spark plug wires and eventually reached the point where you had to put it all back together and make it run. On our first cosmetic restoration, not having a manual, we carefully marked the wires, taped the magneto in the position it came off, and were careful not to turn the engine over while we had these components off. We thought we could get by with this since the engine ran perfectly and would not need any internal work. After the cleanup and painting was done, we began reassembly and finally came to t
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