Did I just "de-magnetize" my magneto???

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Model T Ford Forum: Forum 2013: Did I just "de-magnetize" my magneto???
Top of pagePrevious messageNext messageBottom of page Link to this message  By James J. Lyons III - West Virginia on Saturday, January 12, 2013 - 03:39 pm:

So today, it was finally warm enough to take my 13 Touring car for it's first shake-down run since I acquired it. I didn't go far, only a few miles. It ran well on both battery (12V) and Magneto, but for the most part, I was just running on the mag. However, I noticed it started to lose power. It wasn't missing or sputtering, it just seemed like the farther I went, the less horsepower the engine had. As I was climbing the hill to my house (it's steep) It occurred to me to switch back to battery to see what happens and when I did, the engine instantly snapped back to normal power and operation.

I made it home got it parked in the barn, but then I began to panic and worry that the mag coil was shorting or something like that. Now just for sanity, I began to check the wiring to my battery (which is probably 90 years old) and what found is that the wire with the red clamp and marked positive actually was hooked to the chassis under the car!! So I was running with a positive ground when the coil box was switched on "battery". So can this somehow take the charge out of my magneto? If so, I'm confused as to how. Aren't the two circuits isolated from each other when you throw the switch back and forth on the coil box? I appreciate the advice.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Kohnke Rebabbitting on Saturday, January 12, 2013 - 04:39 pm:

James, the Bat. has nothing to do with your Mag.

Take the Mag plug off the top of the Hogs head, that has the 3 little screws, an take the fuzz off the plug first, that will most times do it.

The next thing would be the switch, don't ever touch a Bat. wire to the Mag., that will kill it.

515-546-4551

Herm.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Hal Schedler, Sacramento on Saturday, January 12, 2013 - 04:52 pm:

If somehow 12V was introduced to the Mag. it will indeed weaken or destroy the magneto. The way is sounds that didn't happen


Top of pagePrevious messageNext messageBottom of page Link to this message  By Peter Claverie on Saturday, January 12, 2013 - 04:56 pm:

First of all, relax! It really makes no difference which side of the battery is "grounded." It is period correct for the Negative to be grounded, but no harm either way. If you switch it, you need to "flash" the generator to re-polarize it. You'll find instruction on this Forum- do a search.

Second, you are correct - There MUST be ABSOLUTELY no connection between the Magneto and the Battery. A cross-connection de-magnetizes the magnets. They can be re-magnetized without much trouble, but first you need to find and fix the possible cross-connection.

Most times this happens either inside the ignition switch, or on the back side of it where the wires connect. But chafed wires can happen anywhere.

To test, get a 12 volt bulb and socket from any parts house. Remove the wire from the magneto post (don't fail to do this), and connect the bulb between that wire and ground. Polarity not important.

Then, mess with wires, switch positions, etc. in every conceivable way. If the bulb lights, you've found your problem. That bulb should NEVER light.

When buying the bulb and socket, while any 12 volt bulb will work, make it an 1157 (or is it an 1156?? Somebody help me here). Then, when you've fixed the problem, and re-charged your magnets, you can use the bulb and an analog meter (one with a needle) to check the output of your magneto. Again, instructions can be found here.

But, before you do all this, check to see if your problem may be a dirty connection to the magneto. Remove the magneto pickup (3 screws) from the top of the hogshead. With a light, look inside. You can see that the pickup is a 'needle' that stabs into a blob of solder on the magneto coil ring. Sometimes that can get goobered up with lint. Sometimes the needle loses its spring. Sometimes it's a mystery what happened, but taking it off and putting it back on restores the connection.

Best of luck!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Charlie B actually in Toms River N.J. on Saturday, January 12, 2013 - 04:58 pm:

Sounds OK from what you did and it's possibly a dirty pick-up as stated. The only thing you might notice is your ammeter will work backwards after you switch the battery to it's correct hook-up of negative ground. Unless of course it was working backwards with a pos. ground. Then it'll be normal when you correct the batt terms. Confused?


Top of pagePrevious messageNext messageBottom of page Link to this message  By James J. Lyons III - West Virginia on Sunday, January 13, 2013 - 07:49 am:

Thanks for all the input. I'm going to fool with it today. I just put an outside oiler on it so I'm going to check the spring tension closely, along with some of the other suggestions.


Top of pagePrevious messageNext messageBottom of page Link to this message  By George_Cherry Hill NJ on Sunday, January 13, 2013 - 09:09 am:

Had something like that a while back. Would run fine on mag going somewhere...coming home always had the last 2 miles on BATT to make a chug-chug spit go away.

Post was clean, switch was good, went through everything known to man, and finally rechecked coils. They had been set right, no double spark, proper bridge spring action/gap, 1.3 dead nuts match, HCCT set. Recheck showed good yet when really putting a spin on the flywheel like a blur...one of the 4 showed a breakdown in sparking.

Never knew why, was an original Ford coil and the guy with the HCCT offered me a straight up swap for one of his later era tuned spares for my 'sometimes' Ford. I took the offer, and for whatever reason, whether the coil or just going thru everything else 'one more time' it has behaved ever since!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Kohnke Rebabbitting on Sunday, January 13, 2013 - 12:54 pm:

You are right George, that has happened to me before!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Steven Thum on Sunday, January 13, 2013 - 03:28 pm:

James

If you just put a out side oiler in, you might want to check to see if the elbo you screwed into the mag post contacts the mag contact post. Some times you need to file the elbo down so it does not short the mag contact post.

Steven


Top of pagePrevious messageNext messageBottom of page Link to this message  By James J. Lyons III - West Virginia on Sunday, January 13, 2013 - 05:40 pm:

I found the problem... Turns out the spring-loaded contact post wasnt making good contact with the magneto. Problem solved! Thanks again for all the help.


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