1947 Cadillac 6 volt coil replacement.

[dino]

Hello.
I am considering replacing the coil on my 1947 Cadillac.  Has anyone had direct experience replacing the original style coil with the coils now available at your local NAPA store.
As you would know the original coil has only one post marked (dist) on the front end.
On the back end ,under the cap, is another post to accept the wire from the ignition switch. That post also excepts the connector from the resistor that is mounted to the coil and housed under the cap.
The new style 6 volt coils have 2 posts on the front end. It turns out one post on the new coil is marked with a + sign the other with a - sign.
Does + correspond to (dist)  and -  to (ignition) ?
If so is it safe to say I would run the wire from the ignition switch to the post marked -  and install the external resistor to the same post .    Do I even need a resistor with a new coil?

Makes sense and sounds simple enough. I just want to confirm with someone who has already done this, I don't want to fry everything.           Thanks....

[R Sotardi #11719]

The coil to dist wire is the same as the battery ground, ie, if your car is negative ground( as a 47 Cadillac) than the dist wire shoud go to the - pole on the coil. Ron

[dino]

Yes  Ron
Car has a negative ground battery.  So (- ) post to distributor...   Thank you for that info.....

Do you have any feeling as to whether or not I need or should even bother to use an external resistor?  The coil can be purchased with or without the external resistor.

If yes would that go on the (-) negative post as well ?

Does the coil without the external resistor have an INTERNAL resistor ?   Maybe I should just use one of those...  What do you think ?

                   Thanks again... Dino

[Wayne Womble 12210]

Use a 12V coil without a resistor. 

If a `47 had a resistor originally with its 6V coil, and you use a 6V coil, you probably should use the resistor. 

[Steve Passmore]

Makes no difference if a vehicle is positive or negative ground, the + on the coil is always from the power source (Ign) and the minus (-) is always the drain (Dist)
Unwise to fit a resistor coil to a standard system as these coils are slightly less voltage (about 8 volts)and require a secondary power supply from the start button, this gives an 8 volt a massive boost just for starting of 12 volts and when the buttons released power reverts back through the resistor side reducing the voltage for normal running. If you run a resister coil on a standard system it will probably burn out and if you run a standard on a resistor system you may have poor starting. resistor coils usually have two supply wires attached to the + terminal on the coil. 
Hope your not confusing a Suppressor attached to the coil with a Resister Dino? different things, theres no internal resistor coils, that would defeat the purpose as you could not wire up a by pass, I don't think they even had resistor systems in the 40s let alone on a 6 volt car.

[dino]

suppressor, resistor, condenser.
I believe we are talking suppressor.. If the suppressor is installed to eliminate radio noise, that's what I'm talking about.    I was told to use a condenser similar to the condenser used in the distributor if I have any radio interference.
The plan is to install the new coil that has written right on it " no external RESISTOR required " all by it self.
If there is no radio interference I would be all set...
If there is radio interference I was told to install the "condenser" on the ignition side of the coil and see if it goes away.....
Your thoughts.....

[Dave Shepherd]

Yes the noise suppressor goes on the pos terminal of the coil, also you see the same thing on the generator and the voltage regulator on some cars.. BTW noise suppressors are different than ign condensors in their capacitance rating.

[dino]

"BTW noise suppressors are different than ign condensors in their capacitance rating"

Thanks for the info Dave.

Do you have any suggestions as to where I could pick up an actual noise suppressor for this car if it turns out I really need one?

PS.. Does a difference in capacitance rating necessarily mean it absolutely will not do the job ?

[Dave Shepherd]

I believe I found some at either a Napa or a Carquest store for a 6v Chrysler product. Try Googling radio suppressor or capacitor for more comprehensive info.

[kkarrer]

Dino,
      I'm replacing the coil on my 41 coupe as well.  How are you going to attach the shielded cable to the bottom of the coil when you go to the later model coil?  My plan is to lengthen the wire and drill a hole in the housing to route the longer wire to the top of the new coil and then epoxy the cable housing onto the bottom end of the new coil.  That way it will look as close to original as possible.  If you use black wire it should be nearly invisible.
Ken Karrer 41 6227D coupe

[R Sotardi #11719]

Dino as the guys stated before and also the part regarding the "supressor". Now, I have a question ... I presume the supressor is rated by microfarads... What is the mF of the supressor on the coil. Also the one on the generator... is it the same? Ron

[Dave Shepherd]

We can't measure it but .3 is about right and they are all the same.

[R Sotardi #11719]

Thanks Dave. By all the same I presume all makes/models with 6 volt use a @ .3 ?

[bcroe]

The exact value of a noise suppressor cap is not at all critical.  It probably starts working 90 %
effective with only 1% capacity.  It won't kill ALL the noise (used with suppression wires and/or
plugs).  Only a shielded ignition does that, as seen on military vehicles & aircraft.  Some of us HAMs
install shielded ignitions.  Bruce Roe  CLC # 14630

[Dave Shepherd]

Thanks Dave. By all the same I presume all makes/models with 6 volt use a @ .3 ?

Bruce's info on the money as usual, yes they are all the same.