No more 6 volt. I am completing the change over and need a correct part number or auto parts store part number. I have read they can range from 0.50 ohm to 1.6 ohm. I have a new 12 volt coil mounted along with the 12 volt relay.


Thanks.....

Boy, it's been a long time, so don't take this to the bank. I think the coil and ballast resistor are a combo, as you're looking for something like 6volts at the points to prevent pitting from arcing. If you used a '56 replacement coil, then go with that resistor. If not, the coil may have contained some literature, or perhaps the manufacturer can tell you. The old Mallory coils I used either came with the resistor, or gave you a part number. Hopefully, someone more knowledgeable will post further.

miker
55 bird, 32 cabrio F code
Kent, WA
Tucson, AZ

Find out what your coil resistance is first. Then do a Google search for the right ballast. You should end up with 9 volts + or_  at the coil in run if you are still using points. Pete

I used a after market resistor for chrysler product(lordco parts in bc. it gave the coiltouch over 8volts runing,cheap and avail.

There are coils made with internal resistors,I have one on my 37 Chevy p/u so it still looks like it is 6 volt.,I think its for a older VW


Butchering up everything I can get my hands on in Dayton Ohio

didn,t ford produce a12 volt coil that didn,t reguire a ballist resistor  because it was bilt into the coil ?

Yes - and I have one on my 12V, 312 powered 54




54 Victoria 312;  48 Ford Conv 302, 56 Bird 312
Forever Ford
Midland Park, NJ

Unless there is an extra post on the coil an internal resistor is of no advantage, as the whole idea of the resistor is to be able to bypass it during start up to counter the voltage drop created by the large draw from the starter motor, and also to give a little extra boost to the ignition during starting. 
The resistor is suppose to match the coil and balanced with the rest of the ignition to prolong points life. The 1957 resistor is specified at 1.3-1.4ohms and it appears to be the same part for 1956. Using the 56-57 version with the correct bracket and coil mount puts it in a good position on the manifold near the distributor. I cant see the sense in trying to hide it if you have a 12 volt battery sitting there.
Don't forget to have the bypass wire from the solenoid otherwise you might get hard starting.  

I think ford had used 12volts for starting and  coil reduced voltage from the coil so they had 2 lines 1 from the ignition to coil and 1 direct from the start side of the ignition switch so that side was only12 volts used for starting only, which probably came from the starter side of the solenoid,  what year they did that I,m not sure ?? so you don,t need a ballist resistor because its built into the newer  coil they use 12 volts just for starting because the starter draws to much  and it cuts back the voltage used at starting  and that's why they have direct  voltage to the plus side of the coil for easier starting 

Bird 292; When I changed my bird over to 12 Volt. The Ballast  Resistor that I used was from NAPA.  Brand name is  ( Standard  Part number is RU-10 )  works great.  Also if you have a problem getting the part, you can Call Prestige  Thunderbird and talk with Frank in parts, They will have that part in stock. 1-800-423-4751   or 562 944-6237
Hope this helps. Bob

Bob