The Stovebolt Site Forums The Shop Area Engine Shop Coil hookup - '54 3100

Hi,

Doing some detailing and mechanical on my '54 3100 so it will hopefully make it from Orlando to the Daytona Turkey Rod Run this weekend ... if the weather is clear.

Three Questions:
>> Question #1) What color was the bracket that holds the coil originally? Unpainted? Engine color? Some other color?

>> Question #2) The truck was converted to 12v by a previous owner. Has a Bosch 12v coil, but it was turned "wire side" up. I disconnected the wires and noted the locations so that I can turn it "wire side" down like the original.

The wire from the distributor was connected to the + terminal of the coil. I read on a Stovebolt post that it should be to the neg. terminal on the coil. The truck ran great before I disconnected the wires.

Did I record the connection wrong? I will replace the points, condenser, and rotor, so I won't know if it runs until I finish.

What will happen if the connections are reversed? Won't run, or sill it blow up in a thermonuclear armageddon?

>> Question #3) Should there be a ballast resistor somewhere in the system? I have't seen one.

Thanks as always for your help,

- Lonnie

The truck ran great before I disconnected the wires.

I would reconnect like it was and drive it to the turkey run

If it ain't broke.Don't fix it:

Lonnie,

Regarding your questions:

1. The bracket is/was unpainted, galvanized, I think.

2. The negative terminal goes to the distributor. If the coil primary connections are reversed, you will be firing the spark plugs with a positive voltage on the center electrodes, which will increase the firing voltage about 10%. You probably won't notice the reversed polarity until the spark plugs begin misfiring under full-throttle acceleration, after the gap increases with mileage. With the 6-volt system, you might also have some hard cold starts in cold weather- below zero temperatures. And, rest easy, your truck won't self-destruct, or blow you up, if you wire the coil incorrectly.

3. There should be a ballast resistor in series with the coil if the system was properly converted to 12 volts, but some 12v coils have internal ballast resistance. Measure the primary resistance of the coil: with internal ballast resistance you should find about 3 ohms, maybe a little more; without internal ballast resistance, the primary resistance should be around 1.5 ohms, plus couple of tenths is alright, but minus not much.

If you are back to 6-volts with the electrical system, you shouldn't have a ballast resistor, nor the coil with internal ballast resistance.

You can use the 12v coil if it does not have the internal resistor, but a 6v coil would be better. If the coil has internal ballast resistance, it should be marked on the case with something like "Internal Resistor", or something similar.

Hope this helps.

Harvester

I turned my coil wire side up. It was easier to see the pointer on the flywheel. To each his own.

The reason that the coils were mounted upside down was that the old oil filled coils stayed cooler with the oil at the "business end" of the coil.

Thanks for the help.

> Harvester:
I changed the coil primaries to be correct (neg to distributor) before I read your response. I found a few posts on some other forums that also said that it will work either way and agreed that it will loose a little firing voltage if reversed.

The resistance across the primaries is about 3.4 ohms, so it looks like I have a coil with an internal resistor - great.

The paint is slowly flaking off of my coil bracket, so it will soon be plain galvanized.

> MarkT:
I see your point that the high tension lead can obstruct the pointer.

> Greg H:
Thanks for the logic behind the positon.

> joker:
Even though it ran well before, I changed the connection, drove it to the Daytona Turkey Run, raised the flag, mounted an info poster, and proudly showed our truck - along with over 3,000 other cars and trucks. Here's my wife with our truck.

Thanks again to all of you.

- Lonnie