MTFCA Forum

Hello, does anyone know what chemicals would you use to clean the wood in a coil box? Basically, what a professional wood worker would use which will not deform or compromise the wood integrity?

Again thanks.

What is the wood contaminated with? Many wood coil box parts have internal faults that cannot be easily seen or remedied. (Carbon tracking). If the wood has paint on it, especially any paint with metallic or carbon pigment, you'd need to sand all of the paint off and then seal the wood with something like Krylon Ignition Sealer. If the wood is oily, wiping it with WD 40 would probably be as good as anything. Cracked, weathered, or badly oil soaked wood will probably cause problems with high voltage leakage.

You can clean the wood with mineral spirits/paint thinner.

No oil! The coil box has been in my cellar for 25 years and has dust including sawdust and is dirty. Basically, whatever a cellar has floating around that is what I need cleaned.

Use a stiff bristle brush and clean out all the dried, loose dust and dirt.

If it requires further cleaning after doing the above, then use mineral spirits/paint thinner as I posted earlier. You can use a rag or scrub it with a toothbrush for that matter.

Truthfully, If you plan to use the box on a car I would strongly suggest you consider replacing the wood with one of the plastic kits. I have helped more than one fellow who had problems with rough running due to carbon tracks or wet wood. Do it once and be done with it.

If the wood has to be cleaned, one would be inclined to think there's more to be done than just the wood. That means taking everything apart including the terminals, porcelain insulators, wood sections, removing contacts from bolts, stripping paint from metal coil box, clean prime and repaint.. cleaning the wood ????... Personally, I think it's better to replace with new wood or the plastic sections that are offered by the suppliers. Wire brush the terminal bolts , nuts, and the contact tabs followed by reinstalling tabs on bolts followed by soldering to ensure electrical contact. Use mixture of boiled linseed oil with a little turpentine/mineral spirits , and give at least two coats to the wood sections before reassembling.... The same mixture can be used on the individual wood coils.... Be sure to reinstall the t-shaped metal brace that goes between coils two and three. Check fitment of coil box lid to the box, using needle nose pliers metal may be needed to be fitted to conform to closure.

Perfect! Just what the doctor ordered.

New wood or the improved plastic AND all new bolts and etc to add for a new box. Make sure you reattach the center metal piece that holds the coils tightly in place for good contact. If you break the tabs to remove the old one be sure to get a new one. Be sure to keep the original coil contacts. They are much better than the reproduction ones.

Do not discard the bronze coil contacts. Clean and reuse. They just dont make those anymore.

Dave, you're absolutely correct on those contacts. The reproduction contacts, when made, were not the same metallic consistency. The originals conduct better and keep their spring ability longer.

Original contacts can be restored - and should be

If contacts are missing and you want to buy cheap junk, then cheap junk you will receive

If you have to buy contacts, then these contacts are made to FORD drawings from correctly spec'd material and are absolutely superior - no cheap junk here: https://www.modeltford.com/item/5001CONBQ.aspx

I used to have a problem, even with the plastic back, where my "original" bronze contacts would lose some of their "spring" resulting in a poor connection to one or more of the coils. I'd have to bend the contact out a bit to fix it My long-term solution? I bought a set of the "good" contacts from Langs and doubled them up with the originals. That was 2022, no problems since. Before you ask, my coilbox never had the center metal piece---that came later.

I know that's not original but hey, it works. You can't see them anyway.

When picking up broken up and mashed up coil boxes for parts I saved them for the contacts and porcelain insulators. Glad I saved the parts. If I remember the porcelain insulators were specific for the earlier cars. They had had a really nice polished finish while the later ones finish was not as polished. Remember reading about it some where.

Not inclined to rebuild box at this time. As has been quoted here on forum,”it’s only original once”. I will attempt to clean and maybe take apart depending on what I see.if necessary will acquire new wood.

Thanks again.

hah wrote: ↑

Tue Mar 17, 2026 12:06 pm

Not inclined to rebuild box at this time. As has been quoted here on forum,”it’s only original once”. I will attempt to clean and maybe take apart depending on what I see.if necessary will acquire new wood.

Thanks again.

I'm assuming that you have a 26' coil box since that's mentioned in your profile. If not this link has all the other diagrams https://mtfca.com/phpBB3/app.php/gallery/album/9

Glazed porcelain insulators would be better than un-glazed ones. At some point, Ford made provision to divert rainwater from the firewall area to prevent high voltage leaks. That may have negated the need for glazed insulators. The glazed ones would be the best choice, if they fit. They will resist dirt and moisture better, and can be wiped clean more easily.

The wood terminal boards are a prolific source of problems due to high voltage leaks that can cause missing, hard starting, and bucking and jerking, especially when humidity is elevated.

Keep it simple at this point in time.

Don't take it apart and clean the interior of the box as described above. You can also polish the contacts.

Put it on the car and test it and if it causes problems, then do a rebuild with new wires and a plastic replacement kit.

On our two Model Ts, we run original coil boxes that have never been taken apart. Never had any problems with them.

Century-old insulation of any type is liable to give problems in high voltage applications. Some types of paint can cause high voltage leaks.