1923-25 Coil Box Differences

[SurveyKing]

Recently I acquired the Coil Box G to replace an older one E that I had. I now realize a significant difference in the two. Both are supposed to be 1923-25 era but as you can see one has 9 contacts and the other 10. My steel firewall on my 1924 has only 9 holes for the 9 contacts on Coil Box E. What is the purpose of the 10 contact box?

[TRDxB2]

Two post - one post for the magneto and the other for battery, power source selected on switch on box and wire then to center strip. Single post has power source selected on dash switch and wire to coil box post wired to center strip.

[Steve Jelf]

The new style coil box with nine terminals and a separate switch on the dash arrived with the starter on 1919 models. The ten-terminal box with the switch on it continued on non-starter cars until 19??. One source says 1921. Another says 1922. Other sources may say something else. I'll leave that research to others.

[SurveyKing]

What should be done with the 10th connector? Just disconnect the threaded screw from the box, then what about the wire that goes do it?

[TRDxB2]

Just a little confused about what you are in the process of doing because of your asking about the wire on #10 and having a 9 hole firewall. Need to understand how your car is wired for the switch on the dash

[Original Smith]

I could be wrong, but if you have a '23-5, the difference is taken care of in the switch and wire loom. Also, your coilbox will have no holes in the front for the earlier style switch.

[SurveyKing]

Thanks for chiming in here Original, the situation is that I purchased a rebuilt coil box which is for 23-25 era, however it came with 10 connectors instead of nine. My question is, what should I do with the tenth connector and wire to make this coil box work for me. The wire loom is the standard starter type for that era.

[old_charley]

Daniel, your post doesn't state whether or not the 10 post box has the switch on the front. If it does not, then whoever rebuilt that box used the wrong wood kit and posts. To use that box you will have to determine which of the two lower posts is connected to the power strip in the box bottom. If it is the one on the box's driver's side I would think you could remove the other post and use the box that way. If the other post is the only one connected to the strip, you will have to disassemble the box to connect the driver's side post and leave the passenger side post off.

Steve, I don't when Ford quit using the 10 post box with the switch, but my '22 factory non-starter touring, build date July 26,1922 has the earlier style box with integral switch

[Steve Jelf]

Why do you want to replace the nine-post box?

[SurveyKing]

Steve, the original box I had was dinged up so I replaced it with a rebuilt one but did not expect to get 10 connectors instead of 9. This is the later style without the switch on the front so am trying to figure a way to make it work for me. Charlie, thanks for you suggestion, I will check that out.

[TRDxB2]

Recently I acquired the Coil Box G to replace an older one E that I had. .... My steel firewall on my 1924 has only 9 holes for the 9 contacts on Coil Box E. What is the purpose of the 10 contact box?

There is some confusion caused by what people are saying that model/year should have vs what it has. Would like to first focus on what you have.
So you are saying that Coil Box E having 9 contacts is the older one? OR did you mean it was the old one. Not sure why you are saying that unless the there is switch on the front of that coil box. I have seen some boxes for a dash mounted switch for sale with post #10 in place (wired?) because the refurbish kit wood & post kit is year independent and cut for the early models which then has unnecessary bottom grooves and holes on the back for the later boxes. They also have a slot for the metal support bar (runs front to back in the middle of the box) that was not used on pre 1922 boxes. If post #10 has no wire connected to it remove it and plug the hole

[Mark Gregush]

For cars;
Coil boxes were the same from about 1919/20 till 1925 (ones without switch on them)
1917 to about 1919/20 with switch on front, the tenth terminal was the battery connection
Wood and metal firewalls from 1917 up to the 1924/25 model would have all 10 holes so could be used as replacement on 1917 to 1919/20 cars with switch on box as well as cars with switch on dash.
The low metal firewall had all 10 holes so could be used as replacement back to 1917.
With the introduction of the 1924 models, the 10th or battery terminal hole was no longer stamped out as it was no longer needed. The high radiator cars firewall could not be used as a replacement on earlier cars, all cars would have had switch on dash.
After about 1920, all cars had switch installed on dash so the 10th terminal was not installed on the coil box but hole in wood/metal low firewall and coil box wood remained.
Wood kits for 1914 thru 1925 have the 10th hole drill so one kit covers many years but was not needed for all years
The 10th or lower left terminal as you look at the back of the box is not needed or used for 1924/25. It can be removed by taking the wood out and unsoldering or disconnecting the lead from the power strip. The person that rebuilt the box did not know it was not needed and simply fill the hole.

[SurveyKing]

Mark, thanks for that information, it makes perfect sense, My box does not have a switch on the front as is for 1924 firewall, so I will dismantle and remove the tenth connector. Thanks to all who have taken the time to add input, I wonder how many people realize the ten verses the nine connectors, I did not have a clue.

[TRDxB2]

Wood kits for 1914 thru 1925 have the 10th hole drill so one kit covers many years but was not needed for all years
The 10th or lower left terminal as you look at the back of the box is not needed or used for 1924/25. It can be removed by taking the wood out and unsoldering or disconnecting the lead from the power strip. The person that rebuilt the box did not know it was not needed and simply fill the hole.

Thank you for confirming me response above. But if #10 post is soldered it would indicate that the box was not wired correctly as the seller claimed and if undersoldered there would be a loose wire in the box.
Hopefully it is not soldered and there is continuity between post #9. If not, the box needs to taken apart to see how the base wood is wired per the diagrams above. There also should be a metal strip securing the front and back of the box located between coils 2 & 3.

[Mark Gregush]

Good point about checking first to see if the 10th is connected! The installed terminal may just be filling the hole. You should be able to see the wire running up from the base in the slot if it is.

[SurveyKing]

After dismantling the box, I found both wires running to the bottom contact plate. See photos. (There is a wire under the tape on the left for the ninth connector) Now if I remove the blue wire for the tenth contact and the connector that is all that is needed, correct?

Coil Box interior

Coil Box Bottom Wiring

[Mark Gregush]

Correct yes.

[Jeff Hood]

Why does your "rebuilt" coil box have all that old wood in it? Often the old wood is the problem with poorly running cars.

[SurveyKing]

Jeff, that may be a good question for the rebuilder. The metal portions were well done, the wood sealed, the contacts replaces and the connector strip replaced all with new. Correct me if I am wrong, but the critical issue is whether the wood will absorb moisture causing a short. I am spraying it again with spar urethane to make sure before assembly. I'd like to know what to use to insulate the water penetration to the underside. Do you put some sort of gasket seal between the lower back part of the wood and the bottom of the metal box?

[Mark Gregush]

You live in Texas how often are you going to get caught in the rain? Ya I know it does rain in Texas, but don't over think it. Unless it gets really wet, wood is fine.

[TRDxB2]

After dismantling the box, I found both wires running to the bottom contact plate. See photos. (There is a wire under the tape on the left for the ninth connector) Now if I remove the blue wire for the tenth contact and the connector that is all that is needed, correct?Coil Box Interio.jpgCoil Box Bottom Wiring.jpg

Yes remove the blue wire. But your not done.
As suggested, you need to seal the wood to prevent "moisture" but not rain water. The coil boxes were made with a just a piece of material glued over any slot containing a wire (like your #9). Back then wire insulation wasn't as good as it is today. Think of this, the box has no drain hole, so if water would get into the coil box it could settle either on the top of the bottom board and/or underneath it and it would take much to cause a short. Not much you can do about that except not getting the coil box wet. Moisture abatement can be done several ways. Spend big bucks and get a new wood/plastic or seal the wood. I like to use a product that is absorbed into the wood sealing it, not just something that seems to just settle on the surface. My choice is Minwax Wood Hardener, others will laud theirs. When you put the box back together make sure you get the lip of the bottom of the box into the slit in the bottom of back board.

[Jeff Hood]

Dan, there may be nothing wrong with your old wood. I was just surprised to see it. As long as it hasn't developed a carbon track you are good to go. In my limited experience it seems that most of the coilbox problems are due to delaminating and carbon tracked wood and badly rusted terminal bolts where they pass through the wood, so I expected to see them replaced. No need to do that if the wood is ok. Same for the bolts, they can be reused if they are in good condition.

In the parts business, rebuilt means taken apart, cleaned, inspected and any bad parts replaced. That appears to be what was done to your coilbox, and you did say it was rebuilt. Remanufactured means all parts replaced except the main components/frame.

[John Dow]

[Original Smith]

Don't use a plywood kit. Lang's offers a solid wood kit which is better than original, but the best kit is Fun Projects plastic kit.

[Steve Jelf]

...the contacts replace[d] and the connector strip replaced all with new.

Uh-oh. The new contacts were notoriously made of the wrong material and were known to fail. I hope you didn't get some of those.

Larry is correct. The best thing for rebuilding a coil box is the Fun Projects kit.