MTFCA Forum

First thank you Joe Bell, better known as ‘Engine Joe’, for your help with the final diagnosis of my ’21 Touring electrical problem! Last Saturday, after spending almost a year out of commission, I decided to carefully wash it, wax it, and take it for a drive. After the wash, it would only run on #2 & #3, but all four coils were buzzing. I called Joe and his advice was to check and see if the spark advance rod or something was arcing to the #1 & #4 commutator posts. Instead, I discovered tiny sparks arcing to the coil box metal on both sides…from the wood! I took it apart and found that the arcing had created a thick path of pure carbon on the wood on both sides of the box (see below). A little rust staining on the wood might have also contributed. After sanding the wood, I further discovered black pin holes at the edge of the wood that extended through the wood to the #1 & #4 electrodes. After sanding, I cleaned out the pin holes and rubbed a heavy coat of silicone on the two edges of the panel followed by a wrap with two small strips of sheet-pvc over the wet silicone. The problem likely began after the bath with moisture getting into the coil box wood. Aside from having to do a sponge bath in the future, doe’s anyone make a plastic board assembly for the Coil Box?

Tom.... Bring up coil box parts on your supplier website, and there are plastic versions for your coil box. The condition you found is called " carbon tracking " . Be sure that you put your coils out in the Sun for them to dry out thoroughly and then follow with a coat or two of boiled linseed oil for further moisture protection.

Engine Joe has helped me and many others. He knows model t inside and out.

Art Mirtes

I remember on a tour I was with had all the T's in the parking lot of the state park,it rained over night, and 1 guys coil box got soaked. If I remember correctly we took turns holding it under the hand dryer in the mens bathroom trying to get it dried out enough to run.

The suppliers sell a waterproof coil box board that was made by FunProjects. If the stock has been depleted & Birdhaven hasn't continued to supply them you can waterproof a wood board. As an example (there are many similar products & some use varnish as well) Products like Minwax below soak into the wood.

Thank you for posting your experiences and the photos! A lot of folks don't realize that the arcing can occur internally, between the layers of plywood.

Snyder's has the plastic rebuild kits.

Go to Google and search the following:
carbon track mtfca.com
I think that you will find out that the carbon tracking has been problem for a long time. Most Model T owners have been there, if not- it's coming! Thankfully, John Regan (Fun Projects), came up with a solution that works. His creation literally stops the problem.

Hey Tom ..... How's your coilbox rebuilding progress coming along?

John Regan's Fun projects kit:

A big thank you to all of you for your wisdom and comments! Thanks John for your initial comments on Carbon Tracking. I got it running on all four after the silicone and PVC.

What you have there is a newer wood coil box replacement..... you should really reconsider getting the non-conductive plastic panel sections so that your past problem does not repeat itself. If you consider using the wood coilbox panels, they should be coated with at least three layers of boiled linseed oil before any hardware is attached to the wood. The boiled linseed oil will seal out any entrance of moisture into the wood for a given time period of a few years when used on the coil box wood and plus the four individual coils.

One can also utilize this unique Casco accessory to keep the water out... have this on my T, and although hidden, it gets the job done woth shield and rubber grommets.

I am not sure how thick the wood is that is used on the coil boxes without going to the garage tonight. Could a person make a replacement from white plastic cutting boards used in the kitchen? The ones we use are 320 thousandths thick and they would not build up carbon tracks. If it would work and you did not want the white to show you could use a dark brown stain on it.

Interesting and timely too! Excellent thread! Glad you're running again Tom.
That Casco is very cool Andrew.
Preservatives for wood: A little off topic. Would Flood's Penetrol work as well as Minwax wood hardener? For coil wood.
The '18 here had his coil box rebuilt in the mid-late 70's with a plywood kit. So far it's been OK but have a Regan-Fun kit stashed.