Quit running on magneto

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Model T Ford Forum: Forum 2017: Quit running on magneto
Top of pagePrevious messageNext messageBottom of page Link to this message  By Ned Brainard on Tuesday, June 06, 2017 - 12:32 am:

My story begins with a 1914 touring car that I have been waking up over the past several months from an approximate 7 year nap.
Running a little rough I read about this fancy futuristic magical machine they call a Strobo Sparker and thanks to the Rose City Model T club in Oregon I was given the privilege of borrowing and rebuilding several coils with new points and caps purchased through Lang's.
Last Saturday having just finished up my last coil my neighbor called inviting the family over to a BBQ, what a perfect chance to try the coils.
The car fired up well on the 12v car battery and then I switched over to mag. Engine ran smoother, and overall had better power, how exciting is that, must of done something right so I'm off to the BBQ.
About 9 pm and 3 hours of visiting it's time to go. Switch off, two chokes, switch to battery and she's running. Switch to mag and she dies. Hmm? Switch off, one choke, switch to battery fires right up. Switch to mag and... sparks and smoke at the switch and she dies. Switch back off and I notice the switch is loose from the coil box.
Sunday morning I remove the front brass switch cover and two of the three brass screws have fallen into the switch. I removed the coils and inside the box are the two brass nuts. A little Loc Tite and the switch is back in place. So I try the car again and the same thing, fires right up on battery but dies on mag.
Some lite reading on the subject and this afternoon I give it the John Regan 1156 test.
Idle: voltage about 6, lamp dim.
Moderate: voltage about 10, lamp bright.
High speed: voltage 12+, lamp super bright but did not burn out.
I have checked continuity in sections from the mag post through the switch to the bottom terminals in the coil box and they all check out.
I removed the mag post and think everything looks ok.
What am I missing?
What happened when those screws sparked in the switch.
I'll try and be a good student and answer all you're questions.
Thanks
Ned


Top of pagePrevious messageNext messageBottom of page Link to this message  By John F. Regan on Tuesday, June 06, 2017 - 08:30 am:

The Battery connection to the switch may have touched the magneto connection to the switch. This would have discharged the magneto magnets. When doing the 1156 test you should be able to get the AC voltage well over 20 volts when you crack the throttle. High speed at 12V out of the mag is not enough. Make sure that all wires inside the switch are making good connection and are connected ONLY to the correct points so that nothing is marginal in there. Make sure your magneto test was performed using an ANALOG meter and not a digital meter. You may have to perform in "in-the-car" recharge of your magneto magnets but for sure double check everything else first since you don't want to do that unless you have nothing to lose. Go slow and be super thorugh before you try something else. Don't start wholesale replacing things in hopes of the problem going away or you may put in more problems rather than fixing them.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ned Brainard on Tuesday, June 06, 2017 - 09:58 am:

Old school analog.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ned Brainard on Tuesday, June 06, 2017 - 10:01 am:

About 6V at idle and a little above 12V at high speed.
I'll read up on magneto recharging.
Any suggestions?


Top of pagePrevious messageNext messageBottom of page Link to this message  By John Doolittle on Tuesday, June 06, 2017 - 10:07 am:

Ned- it appears that you are reading the DC scale. The magneto puts out AC current, therefore set the meter so that you can read the MAX AC current.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ned Brainard on Tuesday, June 06, 2017 - 10:23 am:

Hi John,
There is a switch on the meter (not seen in the photo) for AC readings or DC reading but they share the same scale.
I have the AC set to read 0 - 12V (bottom scale) in the photo's.
When I switched to read 0- 60V (middle scale) the needle didn't really move, indicating I wasn't reading much above 12V at high speed.


Top of pagePrevious messageNext messageBottom of page Link to this message  By John Doolittle on Tuesday, June 06, 2017 - 10:40 am:

For your sake, I guess I was hoping that your were reading the wrong scale. If that had been the case you would have found that the magneto could possible be healthy and hopefully would have a "simple fix".

As I saw it, I could see the 6v & the 12V that the needle was pointing to in the photos and it appeared that I was reading the DC scale.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Norman T. Kling on Tuesday, June 06, 2017 - 10:42 am:

If that reading was taken on the mag post while running on battery, your mag is not putting out enough. Try disconnecting the lead from the mag post and running the test again. It is possible that you have 6 volts from the battery on the mag post because of a short in the switch. If you still have 6 volts at the mag with the lead disconnected, your mag needs charging. If the voltage rises at high speeds, your mag is OK but if you get 0 volts at the mag with the lead disconnected, you have an open in the mag circuit.

I suspect you have trouble in the switch. However, that trouble could have caused the magnets to discharge.

Norm


Top of pagePrevious messageNext messageBottom of page Link to this message  By John F. Regan on Tuesday, June 06, 2017 - 10:55 am:

Ned:

I am not sure I understand what you are reading since if you were reading 12VAC on the 0-12VAC scale and switched the meter to read on the 0-60VAC scale and the needle didn't move then something is wrong with the meter or hookup since the needle would have to move to a different place on the scale. If you understood that and took that into account then your magneto is not strong enough to run coils properly and if you saw sparks near or at the switch then very likely you might have zapped the magneto by making even a momentary connection between BATTERY and MAGNETO. Its an easy thing to do.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Sharon Miller on Tuesday, June 06, 2017 - 12:39 pm:

Gentlemen,

I believe Ned is saying; AC AND DC share the same 3 scales in BLACK. Both AC and DC can read 0-12, 0-60, and 0-300 volts. Thus the BOTTOM 0-12 is not JUST DC. It can be either AC or DC as can each of the other scales.

Cheers,
Terry


Top of pagePrevious messageNext messageBottom of page Link to this message  By David Dufault on Tuesday, June 06, 2017 - 12:54 pm:

Dial Setting? Picture doesn't show..

http://www.triplett.com/wp-content/uploads/2012/11/Model_630_T6.pdf


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ned Brainard on Tuesday, June 06, 2017 - 04:19 pm:

Norman,
The test was performed with the lead removed from the post.

John,
Sorry I didn't write that correctly. when I switched the meter from 0-12 VAC to 0-60VAC the needle moved to show about 10VAC on the scale. Was doing the test alone using all three hands as not to cause any further damage so was difficult to read.
I suspect the dropped screw connected the battery to the magneto as suggested and de-magnetized things.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ned Brainard on Tuesday, June 06, 2017 - 04:24 pm:

Terry,
That is correct. AC and DC share the same 3 scales in black.
David,
The link to the Triplett is the one I am using.
I had the switch below set to read 0-12 VAC then I tried 0-60 VAC.


Top of pagePrevious messageNext messageBottom of page Link to this message  By David Dufault on Tuesday, June 06, 2017 - 05:47 pm:

Thanks - sounds correct position


Top of pagePrevious messageNext messageBottom of page Link to this message  By John F. Regan on Wednesday, June 07, 2017 - 05:18 am:

My very first VOM was a Triplett 630 and I still own it. I just wasn't sure what happened exactly when you switched scales. You have cleared that up. I agree that I think you weakened the magnets in your magneto when the DC of the battery was applied to the magneto post. You are not the first to have that happen nor likely the last. I suggest that an in-the-car recharge be attempted to bring the magnets back up and to restore your magneto to operation.


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