Posted by n9viw on September 19, 2010 at 13:42:10 from (75.105.62.178):
Hey all,
I have a '49 Farmall M that came to me converted to 12v (stock 6v starter and pushbutton start switch, Delco 10si alternator, IH ignition with can-style coil and resistor, copper wires). I keep burning out alternators, and I wonder if the points ignition (or the RF coming from it) may be damaging the alternator.
I found that the previous owner had wired the BAT terminal of the alt. to the ammeter, but rather than having the wire from the other side of the ammeter to the battery, he had them both on the same post. Eh? I swapped the battery wire to the opposite post, and of course, the ammeter went full-range. I plan to replace it with a 60-0-60 ammeter soon.
The second thing I found was that he had neglected to wire ANYTHING to the regulator- no sense lead, no excite wire. Nothing! I found this out after I kept burning out coils (and then resistors, after I learned a thing or two about 6-to-12v conversions), as the alternator was putting out who knows how many volts, unregulated. I say "who knows how many" because I can't actually get a reading on the volts, since the plug wires put out so much RFI all my voltmeters go wonky.
I replaced the alternator with a known-good 10si from our old '82 Jeep CJ-7, and in spite of getting it all connected correctly, it too was dead in short order (regulator again). Could the ignition be damaging the regulators? BTW, no diode, idiot light or resistor in the coil positive lead, just direct from the ignition switch to the coil.
When I replaced the alternator, I also replaced the can-style coil and resistor with a Ford TFI e-frame coil, which is rated to handle a full 12v without a resistor. With this coil, can I switch to spiral-core or carbon-core wires without degrading spark performance?
Ah, the joys of fixing other people's screwups! Thanks for any assistance.
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