Model A Ford 12volt Conversion

[willy carlson]

Can I use a 12volt coil in this conversion without a ballast resistor?

[Bob Call]

WTF? Why would you want to convert an A to 12 volt? Works perfectly on original 6 volt if cables and wiring are in good shape. You can use 12 V without ballast resistor if you like fried points for breakfast. There's reason for a resistor in the 12 V ignition circuit. Use one.

[jpage]

I don't understand the reasoning for converting to 12vt. Again like Bob said ,if the car has a good generator and the wiring is good there should be no need . After all ,these cars lasted alot longer than we will in their original configuration. I had an "A" for 16 yrs and never had an electrical failure. It never failed to start even on the cold days with more than 3 turns! Your choice though,I just hate to see these kind of unnecessary "updates on any car!

[MCHinson]

willy,

First, Welcome to the AACA Discussion Forum.

Second, as you have already been told, The Model A Ford electrical system is designed to work on 6 volts. If you feel that you need to change it to 12 volts, that will only mask whatever problem is there that should be fixed. Sometimes a loose connection, or a corroded connection is causing the problem. Another problem sometimes occurs when a battery cable has been replaced with the wrong sized cable. The 6 volt cable is a larger diameter than a cable designed for a 12 volt system. If you have undersized (12 volt) battery cables, it will cause problems. Steps to correct the problems will result in good trouble free operation without the need to change from the original design. A lot of "upgrades" are not an improvement. It is your car, if you feel the need to switch to 12 volts, you can do so, but based on years of experience, I suggest finding the problem rather than rushing to change to 12 volts.

[W_Higgins]

Can I use a 12volt coil in this conversion without a ballast resistor?

In answer to your question, it depends on your coil. You should use a resistor unless your coil has an internal resistor. The need for such will usually be printed on the outside of the coil, or else you can look up your coils part number to be sure.

[Bill_N]

Can I use a 12volt coil in this conversion without a ballast resistor?

Few things depress me more than looking under the hood of a Model "A" and seeing a 12V alternator. There might as well be an early seventies Pinto engine in there to go with it. But, that's just my own taste - and it's your car to do with as you please. Having said that, I don't personally have a problem with things like modern points - things that don't change the look and feel of the Model "A".

One common problem with the original Model "A" electrical system was a bad battery ground. The positive cable bolts to the cross member behind it, but the cross member can lose continuity to the frame over the years. One way to fix this is to run another ground cable (discretely) from the cross member to the frame.

Bill

[bofusmosby]

When I first got my 37 Pontiac, I put a new battery in it, but it was still slow when cranking. I heeded the advice to what the others had said, and I found that my car indeed had a 12 volt battery cable. I got the correct cable, and never any other cranking problems. (plenty of other problems, but not with the cranking)

[MrAlternator]

I understand the idea of keeping the vehicle original , I have alot of customers that drive there car from show to show with an alternator and put the generator back on for shows , It also seem more and more people use there vehicle for just cruising and they want to use halogen bulbs and other 12 volt extras, That is why we design alternators conversion units for 6 volt 8 volt and 12 volt systems, positive and negative ground, we also Have a 12 volt starter for Model T's , we still rebuild original generators and starters, if ever any questions concerning your system , please feel free to ask, we Love to provide free advice and information, and attend more the large antique shows across the country ,

[carlnut50]

Hi Willy, You need a resistor in series with the coil. You can run most any coil handy, I used an AC Delco I had laying around. As far as changing to 12 volts goes, do as you wish and don't worry about the negative comments. I changed my 31 Ford to 12 volt neg ground because I wanted a LED strip stoplight in the rear window and the 12v neg was the cheapest. Also, at the same time I needed a new battery and 12v was cheaper. I already had a good used alternator and the bulbs. Labor is free so it made good sense to do the conversion. If I ever need an electrical part while on a trip, it will be easy. I hope I don't cause anybody to be depressed looking under my hood at an alternator, but if so then I would say don't look. Like others said, the model A is good 6v but alot of early 50"s cars like Chrysler stuff really benefits from 12v conversions. I have experienced it first hand. The manufacturers realized it too.

[bofusmosby]

If you DO convert it over to 12V, I would suggest that you keep all the original 6v items you removed. This way, if you ever sell the car, this will make the "purist" happy, and not be turned off by the conversion and still be a prospective buyer.