12 Volt Conversion

Muttley

Muttley

Senior Member
Dad is wanting to convert electrical system in his Coupe to 12 volt. I've done a couple of searches here but the only things I come up with are posts saying "do a search" or "why would you want to do that?". Does anyone have a simple diagram of which wires need to be switched/replaced/run to complete the conversion? And please, don't clog up this thread with "WHY?!?!?" or similar posts.
 
iI is not that difficult to do. You need to invest in a 12-volt battery, a 12-volt alternator, a 12-volt ignition coil, and install a dropping resister that installs in the back end of the ahooguh horn. You will also need to replace all the light bulbs with 12-volt.

Since you will be reversing the battery polarity to a negative ground you will want to switch the leads around on the ammeter so as to give the correct reading. The polarity of the new 12-volt coil needs to be checked as well.

Bratton's carries the horn dropping resister it snaps into place with little effort.

Everything else remains the same.

Go for it!

Tom Endy
 
Really no wires need to be switched.
The bulbs need to be replaced, if changing to negative ground the battery leads need to be reversed, generator flashed, coil primaries reversed and ballast added, ammeter leads reversed, horn changed or resistor added.
 
The wires can all stay, but if you are also switching to negative ground then you need to swap the two coil primary wires and swap the two wires on the rear of the ammeter.

You'll need to replace all the bulbs with 12 volt bulbs and add a ballast to make the coil work on 12 volts without overheating. The generator can put out 12 volts and keep the battery charged, but if you use an electronic voltage regulator, that will also need to be changed.

12 volts be be tough on the starter, but some guys do it anyway.
 
If the wiring is original style and you plan to use a one wire alternator and convert to negative ground, here goes. Install 12 volt battery connected negative ground. Reverse the wires on the on the ammeter. Reverse the wires on the coil and install a ballast resister. The other choice would be to use a 3.0 ohm internally resisted coil. If the coil is an oil filled style, mount it with the wire connections and tower pointing upward to avoid oil leakage and coil failure. I use the Pertronix Flamethrower epoxy filled 3.0 ohm coil mounted in the standard manner with no ballast resister needed . Part number # 40611 It is possible to run 12 volt positive ground with the original generator with no mods to the generator and no wiring changes at all to the original wiring system. The six volt coil can be used with no wires changed but a ballast rester will be needed. I use the the pertronix flamethrower coil part #40611 epoxy 3.0 ohm mounted in the usual manner. An original, Not repro cutout can be used with this 12 volt setup. I use the Fun Projects 12 volt can style positive ground regulator with mine. This regulator mounts in place of the cutout with no mods needed to the original generator. Check out www.funprojects.com .Of coarse the common sense stuff like bulbs and possible resister for the horn will be needed with either 12 volt conversion.
 
George is one of our pros here. He clearly did not say he considered it hot rodding, but rather was referring you to a good source of info beyond what this board will give you
 
why would you want to change to 12 volts,been driving Model A's since 1961,the 6 volt system is very reliable,only switched to a alternator.
 
I've run unmodified model A starters on 12 volt for many years . The original bendix can give problems no matter what the voltage. I recommend the modern barrell starter drive, either way. The barrell drive has no bolts to drop in the flywheel housing.
 
"why would you want to change to 12 volts,been driving Model A's since 1961,the 6 volt system is very reliable,only switched to a alternator."

He already made the decision and was not asking for help making the decision. Maybe he wants to run a GPS or phone charger or whatever. Who cares???
 
rocket1 said:
Why would you want to change to 12 volts? I've been driving Model A's since 1961, the 6 volt system is very reliable, only switched to a alternator.
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Congratulations, that's 12 years longer than I've been alive.

tbirdtbird said:
Why would you want to change to 12 volts? I've been driving Model A's since 1961, the 6 volt system is very reliable, only switched to a alternator.

He already made the decision and was not asking for help making the decision. Maybe he wants to run a GPS or phone charger or whatever. Who cares???
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No GPS or phone charger, this car is strictly traditional. I'm changing it over because the charging system sucks and I hate working with this positive ground system.
 
rocket1 said:
why would you want to change to 12 volts,been driving Model A's since 1961,the 6 volt system is very reliable,only switched to a alternator.
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Yes, of course six volts will work. I've run my september 29 on six volts since 1960. Here is why I have changed other model A's of mine to 12 volt. Twelve volt is a more powerfull, more reliable system. You get quicker starts. twelve volt batteries charge quicker. Slightly weak six volt batteries usually don't have the power to turn the engine and fire the spark plugs at the same time. Sure , the hand crank can be used but my girls refuse to use the hand crank, they say its just not lady like. I like to show off and use the hand crank at times but don't want to be forced to. My model A's are all in super good tune . Six volt batteries and componets aren't allways available. Yes, we've got a farm supply store and they've got a truck load of 6 volt batteries, I've looked and they are all over a hundred dollars each. I can usually buy a 12 volt battery at Walmart that fits perfectly for $59.95 . I see no reason to use a weaker system that costs more if I don't really have to . A 12 volt conversion is about as simple as anything could be. Not a single wire has to be changed as long as it remains positive ground. even the original generator works with no mods necessary. The original starter will pull the car like a golf cart in high gear on 12 volt if needed to get off the road if other problems exist. Twelve volt has been the standard for the automobile industry for nearly sixty years and there is no reason to fear it. A properly converted model A will show no change unless a person is looking at the battery. Just my thoughts and experience with twelve volt converted model A's .
 
Purdy Swoft said:
I've run unmodified model A starters on 12 volt for many years . The original bendix can give problems no matter what the voltage. I recommend the modern barrell starter drive, either way. The barrell drive has no bolts to drop in the flywheel housing.
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X-2 on Purdy's message ! Will save you money and trouble ,i.e.- original starter (6V) with modern barrel starter drive !

Muttley, I'm wondering what's going on with the SEARCH function here ? This same subject with same comments/advice has been discussed on MANY occasions...frustrating why such mundane and often answered questions/ info can not be found :confused:

BTW. ...I've been using an ORIGINAL 6 volt starter, with modern barrel drive for dozen years now...on 12V with no trouble. Starter has not even been rebuilt !
One warning tho...try to get an ORIGINAL starter switch and check it out/cleanup before use. The repro switches are not worth the heartache,eh !!
BTW...there is NO other site/location that can / will give you better, more knowledgeable information regarding Model As ...than right here :)
 
hardtimes said:
One warning tho...try to get an ORIGINAL starter switch and check it out/cleanup before use. The repro switches are not worth the heartache,eh !!
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No worries about that..........I already took that POS out, installed a solenoid and made it a push button start. ;)
 
Yes, switch all the wires from one post to the other on the rear of the ammeter.
I can only think of the instument lamp wire besides the in and out wires leading to the firewall terminal box.
 
I'm pretty sure there is (at least) one more wire back there but I'm not positive about that. When the time comes I'll check and see where it leads to and report back here to confirm before making the final connections.
 
Muttley said:
Congratulations, that's 12 years longer than I've been alive.




step one in asking a question on this forum respect your elders , and im only 9 years older than you . you gotta take the good and the bad when asking a question like this on a forum about restoration. :) lighten up
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