MTFCA Forum

Hi all,
I just took off the hogshead to change my bands. One of the mag coils has no covering on it. It's the one by the starter hole. Is there a way to cover it up with something like RTV, or liquid rubber? Thanks.
John

You would use Insulating varnish if you could get it clean enough to stick, you can't so don't try. You would never get all the oil out of the windings and covering would fail.

and rebuild it!!!

Paint on 6 coats of oil proof 1201 Glyptal Red Insulating paint is what was originally used on Model T mag coils and the field coils of the starter and generator. Developed by Thomas Edison, “Glyptal” is still the best, but you must clean the oil off completely with Mineral Spirits (not Lacquer thinner) of the area being coated. Jim Patrick

Thank you for the replies. What would be the danger of not doing anything at all? The coil is right next to the starter shaft notch and it is only uncovered about half or less (see photo). All other coils are intact. Thanks.
John

This is what I think has happened to your winding. Someone at some time has tried to remove the starter without first removing the bendix. when they pulled the starter, the bendix bumped the coil and damaged the insulation. You don't say whether or not the magneto worked before you discovered this damage. If your fix doesn't work, you will have to pull the entire engine and transmission and separate the transmission from the engine to replace it. So do it right the first time.
The cost of replacing the entire coil ring with a rebuilt one is worth it. I rewound 3 rings following the instructions in the booklet published by the club. "electrical system". I got the insulators from an electronics supply store and made them to fit. i used fiberglass tape to wrap insulate as I wound the coils and wrapped them with it. Then I got from the local boat yard some boat resin to coat the entire assembly after it was installed and soldered. I used 2 of the rewound rings in my cars which both work. I donated one to the local club which was auctioned off and haven't heard anything about it, so it must have worked. Don't rely completely on what I posted above, but get the booklet and follow the illustrated description like I did about 25 years ago. I have given you from my OLD memory, but the booklet method works.
You can also buy them already rewound from the vendors. I have done that for one other car I have and for several friends, and they work fine too.
You can also charge the magnets and set up the clearances.
Norm

I have mag rings with some insulation missing and they work fine. There is insulation between the ribbon in the spool, insulation wrapped over the spool, and insulation between the spool and the iron ring. Depends on what insulation is missing. A little off the wrapping may not be a problem, not a problem worth pulling the engine for. Applying anything to the coil now after decades of immersion in hot oil will probably not stick. If your car runs fine on mag don't worry about it and address it later when you need to pull the engine to refreshen or rebuild.

It would be a good idea to make sure your coil works before doing this work because, If the mag coil does not work, it would be a waste of time. The best thing to do would be to locate a mag coil technician and send your coil off to be completely rebuilt. Jim Patrick

…Some of this post was removed due to possibly inaccurate or misleading information. Jim Patrick

I'd leave it alone. If several turns of that coil are shorted to each other, the magneto will still work at 90+ % output, assuming the magnets are good and the gap is close to spec. If the coil is shorted to ground, the magneto will be very weak or dead. If the coil is open, the magneto will not work at all. I agree with the others that it's unlikely that anything daubed on the coil will remain there, and I'd add that poking at it may cause problems. I'd be very careful that nothing touches the coil when installing the starter, and hope for the best.

Pretty sure the wire used in the mag ring is not varnished, that is what the paper between the layers is for. That paper is what holds the oil and is why just cleaning the outside is not going to do the job.

Since the insulation is missing in that spot and the winding isn’t damaged I would leave it alone and drive it like it is.
Assuming that your car runs well enough on battery and mag also, install a transmission filter screen and don’t worry about it. There are T’s out there that the original mag ring is still in cars and working.
If something gets loose in the engine such as a piece of babbitt and etc you would know it soon enough whether you have a rebuilt mag ring or not!
Just use a rebuilt coil ring the next time you need to pull the engine for something.

And if your car quits on mag, switch to battery and get home to check out what caused it.

It will probably last longer than you think if nothing gets loose to tare up the mag ring.

As others have said I don’t think the winding is flaking off by it self yet. It probably was nicked when the starter was removed in the past.

If you decide to leave it as is or actually on any T, if you are driving along and it starts to quit or if you have forgotten to switch to mag after starting the engine, be sure to put it into neutral and back off on the gas when you make the switch. Otherwise you run the risk of blowing off the muffler. It will make a big bang as the unburned fuel explodes.
Norm

That is a common problem caused by trying to remove the starter with the Bendix attached.

I have used 5-Minute epoxy for more that 30 years without ever having a problem with it.

First, clean the area of oil as much as possible.

Like others have said, I don’t think it will be possible to get any type of coating or sealant to stick to the coil after being soaked in oil for close to 100 years no matter how much you try to clean it.

I also don’t think Ford ever used red Glyptal on mag coils when new.

Look at the flywheel ring gear! In my opinion the missing insulation is the nat sitting on the trunk of the elephant in the room. The much bigger problem, are the teeth worn so much on the flywheel. And what all that metal in the oil has done to the babbitt. ???