Battery GOOD -- Mag BAD

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Model T Ford Forum: Forum 2012: Battery GOOD -- Mag BAD
Top of pagePrevious messageNext messageBottom of page Link to this message  By James Adair on Tuesday, May 15, 2012 - 04:53 pm:

History: She runs good on battery. Runs great on mag -- except yesterday. Started on Bat, switched to Mag, as usual, started moving, shifted in high and, Holy Cow, the old girl started bucking, missing, stinking and just really objected to running. I coaxed it along for a couple blocks, stopped, turned the switch off. Started all over again. Same result -- Magneto problem? What? Help!! Please!!
Jim


Top of pagePrevious messageNext messageBottom of page Link to this message  By Will,, Trenton,,,New Jersey on Tuesday, May 15, 2012 - 05:03 pm:

If it ran good on mag not that long ago it should run good now, Check for a broken wire.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dan Treace, North FL on Tuesday, May 15, 2012 - 05:05 pm:

First check, switch, be sure the switch to MAG is working well, jiggles on a poor switch can cause issues.

Second check coil box to be sure all the coils are firing on BAT. And the timer contacts are clean, and engine runs without that missing on BAT. Then switch back to MAG and see if all is well.

Third, clean the magneto contact on the hogshead, even a bit of oily waste (lining) mixed with tiny powder of worn off metal from internal parts on the pickup of the contact will intermittent short the contact.



After that, time to test the magneto output with Regan bright bulb test and analog meter.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jim Patrick on Tuesday, May 15, 2012 - 05:41 pm:

You may want to consider sharpening the post contact so it will not only make contact with the solder button on top of the mag coil ring, but will stick into the button. My T once quit after going over some rough railroad tracks. It would start on BATT, but would quit when switched to MAG. I wound up having to drive home on BATT. When I got home, I unscrewed the mag post and saw that it was slanted to one side with a dull point. I sharpened the tip with a Dremel tool, straightened the contact shaft so it was centered in the post and carefully screwed it back in all the way. Problem solved. Jim Patrick


Top of pagePrevious messageNext messageBottom of page Link to this message  By James Adair on Tuesday, May 15, 2012 - 06:13 pm:

Thanks to all. I will check out all these suggestions as soon as I get this suit and tie off -- probably this week-end :-). I really appreciate your help. Jim


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bob Bishop, San Diego on Tuesday, May 15, 2012 - 08:24 pm:

Jim,
Do as all said above. Easiest is to check magneto post for lint and/or contact with solder button.
Had same problem after years of running great on mag. Turned out not only had short in ignition switch (fabric covering had worn thru and bare wire was contacting metal), but also had broken wire in coil box that had previously been repaired sometime in the past(poorly). Rewired ignition switch (simple, only 2 wires, 18 ga.) and coil box, did in-car recharge of magnets and everything works great again. Good luck.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jim Patrick on Tuesday, May 15, 2012 - 08:55 pm:

Sometimes, just the vibration of the T can cause the contact post to slip off the button, especially if it has a dull point. Jim Patrick


Top of pagePrevious messageNext messageBottom of page Link to this message  By George Button III (Chip), Lake Clear, NY on Tuesday, May 15, 2012 - 11:26 pm:

Dan, just heard about the dirty mag post yesterday! I will check mine tomorrow.
James, I am having similar problems. Please let me know what you find. My mag tests good on the voltage.
Good luck and Thanks....Chip


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