Magneto question

Topics Last Day Last Week Tree View    Getting Started Formatting Troubleshooting Program Credits    New Messages Keyword Search Contact Moderators Edit Profile Administration
Model T Ford Forum: Forum 2005: Magneto question
Top of pagePrevious messageNext messageBottom of page Link to this message  By Ryan Miller on Thursday, February 21, 2008 - 05:19 pm:

This is my first model t so this is probably a simple question. Can you charge the Magnets while still attached to the flywheel. Secondly, what is the best wat to do this? Lastly, what is best to use to clean and test the magneto coils.

Any direction would be appreciated. Thanks, Ryan


Top of pagePrevious messageNext messageBottom of page Link to this message  By Frank Fenton on Thursday, February 21, 2008 - 06:47 pm:

Ryan,
You will get all sorts of opinions on this, but if all fasteners are tight and in good condition, I just lay a good coil on the magnets (with the transmission drum end sitting in a bucket for support). Then 'flash' 36 volts across the coil by connecting the positive clip securely to the top 'solder puddle' connection of the coil and then momentarily touching the negative to the coil frame. Touch it or 'strike' it momentarily to the frame 10 or 12 times. I usually use two 12 volt batteries and a battery charger (on boost setting) to get the 36 volts. Don't make a connection for more than a fraction of a second.....just a flash so you don't overheat the coils. I have not found that it is necessary to maintain the original polarity with the magnets. The one we did last week produced 30 volts at the mag terminal with .025 installed clearance between the magnets and the coil. Note that you'll have to carefully pry the coil off the magnets.... don't nick the insulation on a coil.
To test the coil, pass a low current through the coil and test for magnetism at the center pole piece of the coil. Every coil should produce the same amount of 'pull' when you touch it with a screwdrive or wrench. You must limit the current or you will burn out the coil quickly. I use about 25 feet of 18 gauge automotive hookup wire between the positive battery terminal and the coil terminal. This limits the current nicely, but allows enough to test for proper operation. The wire will eventually get hot, so hook it up, test it and disconnect it as quickly as possible.
Frank


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ron Patterson on Thursday, February 21, 2008 - 08:33 pm:

Ryan
While I agree the method above will work there are additional considerations that should be addressed.
1. Model T flywheel magnets are prone to cracking. Cracked Magnet I have rebuilt many flywheels and rarely find one without at least one cracked magnet. You don't even want contemplate the effect of a broken magnet launching inside your new engine.
2. The magnet clamp screws are commonly crystllized and should be replaced. Crystallized Clamp Screw
3. If your flywheel has aluminium magnet spools they are very likely to be badly internally corroded and need replacement. If you have brass magnet spools they may be safely reused.
4.I strongly suggest recharging the magnets back in their original North/South polarity. If you do not their magnetism will deteriorate much faster.
5. You can certainly test a used field winding using the method above, but trying to clean and reuse a field winding is false economy. They are oil soaked, the windings cotton wrapping is rotten and you cannot reliably reseal it. If it fails it not easily repaired. I strongly suggest you spend the $150 and get a properly rebuilt unit.
Just my view.
Ron the Coilman


Top of pagePrevious messageNext messageBottom of page Link to this message  By Katy on Friday, February 22, 2008 - 12:17 am:

When setting the magneto gap, is it necessary to set the gap all the way around or just set the top portion and let the bottom look after itself?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Royce Peterson on Friday, February 22, 2008 - 08:16 am:

Katy,

You won't spend an extra 30 seconds by checking the gap all the way around. It needs to be within limits everywhere. You will typically take the flywheel off and reinstall it two or three times while swapping shims around to get the gap set. The whole process might take an hour if you are not interrupted by a frosty malted beverage break.

Royce


Top of pagePrevious messageNext messageBottom of page Link to this message  By katy on Friday, February 22, 2008 - 11:27 am:

Well, it's my understanding that the bottom flexes and has a built in about .010" difference than the top, so I surmised that if it was left to find it's own place the combination of flex and magnetic attraction would pull it closer to the flywheel.
I would hate to set it at .025" all around and then have the bottom section start to rub as the magnets pulled it closer.
Or is this where the spec of .025"-.040" comes into play?
.025" at the top half and .040" for the bottom half?
The more I think about this the more confused I get.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ron Patterson on Friday, February 22, 2008 - 11:51 am:

Katy
If everything is put back properly it would be some time before the gap would close so much to cause rubbbing.
I suggest you add an additional .005 to the bottom half of the standard Ford magnet to field ring gap. This is to make up for the flexing of the unsupported bottom of the field ring. For those of you who don't think the field ring flexes place a dial indicator on a hand cranked coil tester and move the flywheel and look the cracks commonly found near the bottom mounting bolt holes on field rings. I have heard theories that this additional gap is to make up for the sagging transmission, but that is nonsense. If it was sagging that much because the fourth main was not set correctly in a properly aligned engine pan the crankshaft would be broken very soon.
Ron the Coilman


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ryan Miller on Saturday, February 23, 2008 - 12:02 am:

Thanks for the information. I will give it a shot. Ryan


Top of pagePrevious messageNext messageBottom of page Link to this message  By katy on Sunday, February 24, 2008 - 12:52 pm:

Thanks Ron, I suspected the botton shuld have a bit more clearance than the top.


Posting is currently disabled in this topic. Contact your discussion moderator for more information.
Topics Last Day Last Week Tree View    Getting Started Formatting Troubleshooting Program Credits    New Messages Keyword Search Contact Moderators Edit Profile Administration