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Old 07-09-2010, 07:33 AM   #1
C26Pinelake
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Default Advice to change 6 volt to 12 volt Model A

Is there a step by step process ? Do you need to change the starter ? I intend install a 12 volt alternator and battery. Do I buy 12 volt positive or negative alternator ?
Do the gauges and horn need to be changed. I expect I have to change all bulbs. Thank you for the advice in advance ?
Please reply to Wayne at mcmimmcs@mnsi.net
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Old 07-09-2010, 07:47 AM   #2
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Default Re: Advice to change 6 volt to 12 volt Model A

12 volt negative altrnator. and dont forget the smaller diameter pulley. You will need a 30 amp amp gauge (less likely to burn out with the initial voltage surge when the 12 volt alt kick in). You will need a coil with internal rieister or add a 12 to 6 volt resistor. You will need one of the horn resistors that the vendors sell (the 12 volt will ruin the horn - ask me how I know. Change all bulbs. Your starter will be fine as a 6 volt starter. The down side is the intiial jolt of the 12 volts will eventually break the bendix bolts or the spring.
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Old 07-09-2010, 11:02 AM   #3
Patrick L.
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Default Re: Advice to change 6 volt to 12 volt Model A

Is there a reason for changing to 12v ?? And even if going through with the change is there a reason for not using the generator?? I'm just curious.. Using the 6v starter is fine, but, you might want to install a modern bendix/drive..
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Old 07-09-2010, 12:19 PM   #4
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Default Re: Advice to change 6 volt to 12 volt Model A

Thank you both for the reply. I was changing to go to halogen headlights a radio and an electric heater. Thanks Wayne
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Old 07-09-2010, 01:13 PM   #5
Freddie (Memphis)
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Default Re: Advice to change 6 volt to 12 volt Model A

Wayne...careful, you may get more questions about "why would you want to change to a 12v system when a 6v works just fine" rather than answers on how to do it.

But....kenparker's information is pretty much right on target. You may want to just substitute a 12v coil for a 6v one. Most 6v coils I found available locally had an internal resistor that allowed only 6v to get to the primary windings. Like the externally mounted resistors, these cause a lot of heat. Normally, not an excessive amount of heat, but enough...I don't like 'em.

The only thing kenparker left out was replacing the oriignal Bendix drive with a modern one...that alleviates the broken spring problem which can occur with the original Bendix. They're easy to install and pretty much a one-time thing. The original springs have a nasty habit of breaking when the starter is hit with a 12v battery...and the broken spring parts usually fall down inside the flywheel housing and jamb up the flywheel and starter, which pretty much requires major surgery to remove. You can try to fish the parts out with a magnet...or just save all the drama and headaches by replacing the oriignal Bendix with a modern one in the first place.

Also...Les Andrew's book, Model A Mechanics, Vol II, has a complete step-by-step process to convert to a 12v system. That's what I used and had no problems whatsoever. You can buy both volumes through MAFCA's website, or most of the parts houses carry them, too.

Hope this helps, Wayne...
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Old 07-09-2010, 02:43 PM   #6
Kevin in NJ
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Default Re: Advice to change 6 volt to 12 volt Model A

How big an electric heater??

You might be talking too big a load.

An very overlooked fact about alternators. Just because they are rated 60 amps does not mean they can actually produce such levels when installed on the Model A.

Look back to the days when you have a V belt and an alternator. Look up the how you are supposed to tighten the belt. You are supposed to get the belt very tight. The rule was if you could spin the alt pulley with a finger then it was too loose! If you tighten the belt to the belt tension spec you would have the belt so tight it would sound like a guitar string. If you look closer you will find the belt was also set up to go around the pulley to get a large contact area.

When mounted on the A there are several reason why you are unlikely to get maximum output. The pulley has a small diameter and the belt has a small contact patch. The small diameter is needed to get the RPMs up for the alt to work. To prevent water pump failure few actually make the belt very tight. It has been my experience that the belts are loose to very loose. The pulley on the alt can be easily moved with a finger. Some will even spin with minimal effort.
Any load beyond a basic load will cause the belt to slip.

So before you make your conversion you had best check the amount of amps the heater needs. A 150 watt heater needs 12.5 amps at 12 volts. That is a pretty small heater for a drafty A. Heaters are a resistive load, so it might work at 6 volts taking 25 amps. You could go to a 6 volt alt or a later high output gen and run the heater at 6 volts.

If you are going use a lot of amps then you best consider the condition of your water pump. As you are going to have to tighten the belt to get something more than a small fraction of current from the alt.

The best thing you can do for bright lights that let you drive 60 MPH at night is to get the direct replacement halogen bulbs that are made in Australia. They are found in the back of the A magazines and several parts suppliers now carry them. They can be bought in 12v and 6v. These bulbs will work fine with a generator on a 6 volt system. I think my brother has been running with the same bulbs for 8 years or so. He is running a gen with a diode cutout, no regulator.

There are options for radios today that could allow you to run off of 6V. Many only need 3 volts, you just need to be creative.

You also have to understand the going to 12 volts to fix any problems does not work. You will only mask problems that may come back to haunt you. So before you convert make sure your 6v system works 100%.

In any case, step carefully. You can spend a lot of money and not really be better off in the end.
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Old 07-09-2010, 03:25 PM   #7
Dick Carne
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Default Re: Advice to change 6 volt to 12 volt Model A

I have been running 12 volt systems on my two Model A's for the past 5-6 years, and would not go back. I had initially run a 6 volt alternator, because the generator just didn't seem to generate enough current to keep bright lights, and if I set the charge rate up on the generator, I would have to go back in and run it back down if I was going to travel any significant distance the next time out.

But even the 6-volt alternator did not produce enough current to run halogen bulbs and keep bright lights at stop signs and traffic lights at night, hence the decision to go with a 12 volt system. After swapping bulbs, coil, alternator (be sure to use a 30-amp ammeter), everything runs fine. And I only have to barely touch the starter to get it going. There's no dimming of the lights at stops either.

The caveat to replace the bendix drive with a modern drive is also good advice and money well spent.

Good luck whatever you do!
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Old 07-09-2010, 03:26 PM   #8
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Default Re: Advice to change 6 volt to 12 volt Model A

One other thing to remember ... if you convert to a 12-volt system, be sure to run a 12 volt coil with an internal resister.
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Old 07-09-2010, 03:45 PM   #9
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Default Re: Advice to change 6 volt to 12 volt Model A

Dick Carne, Right on, Glad to see new people with open minds. Really , why should anybody give a damn if a guy wants to run twelve volts?
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Old 07-09-2010, 04:27 PM   #10
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Default Re: Advice to change 6 volt to 12 volt Model A

Quote:
Originally Posted by Purdy Swoft View Post
why should anybody give a damn if a guy wants to run twelve volts?
Since you asked. I've been around Model A long enough to see owners want to change things thinking they have too.

Let me give you some examples;

Install the new Zenith carb. Dyno test have proven that a rebuilt old Zenith will provide GREATER horsepower then the new but it is easier to just buy something then have the old sent out, even for the same money. New must be better!

I need Halogen lamps, instead of properly aligning, focusing, cleaning reflectors.

My front end shimmies so I need a "steering stabilizer" instead of rebuilding the axles and steering parts.

I need juice brakes so I can stop better instead of adjusting what is already there. Some how locking up the wheel with juce brakes is better than locking them up with stock brakes.

I need 12 volt so I can get a jump start.

Do I need to go on?

Does someone want to make the changes because they want to, since it is their car or do them want to make changes, or because they think it is better due to poor maintenance?

We ask the question why to get to the real reason for the change.

And since the Admin of this site has stated; "The ford barn will focus on restoration... And stock fords. We might have a side bar here and there, but restoration will remain the focus. Once the novelty wears off the new format, we will start pointing more in that direction.", we ask the question why to try to maintain a stock model A.

With all that said, this is from Kens garage;

Battery

Any good 12 Volt battery will do as long as it will fit your battery box and hold down. I selected a 72 month, 675 cranking amp, universal battery.
Alternator

I installed a GM 63 Amp Alternator with an internal self exciting voltage regulator. The hook up is one wire, the same as the existing generator. You will need to make two small brackets to mount the alternator or you can use two shackle bars and drill out for the proper size bolts. An alternator pulley can be purchased from your friendly Model A parts supplier.
Starter

No modifications are necessary to the starter. Just touch the pedal and enjoy really fast starts.
Ammeter

I changed the standard 20 amp ammeter to a 30 amp ammeter as an alternator will peg the standard meter. You must reverse the leads on the ammeter due to the change in polarity of the battery. Your neighborhood Model A parts supplier carries the 30 amp ammeter.
Headlights

Since I installed an alternator I opted to go all the way for headlights and convert to Halogen bulbs. The conversion is relatively easy. You can purchase a kit to modify your existing reflectors or you can purchase new reflectors with the Halogen sockets installed. You must install an alternator to successfully operate Halogen bulbs.
6 Volt kits are available. What a pleasure to be able to really see while driving at night.
Ignition

You could install a 12 volt coil and a resistor to reduce the voltage to the points.
I elected to install a PerTronix IGNITOR electronic ignition system. This is an extremely easy system to install as it fits entirely inside the distributor; no outside boxes are required. Kits are available for the standard Model A or B, early V8, and Mallory distributors. Both 6 and 12 kits are available.
Kits are furnished with a new coil as the correct coil resistance is very important for proper operation. Kits are distributed by: Remund Ignitions, Inc.
P.O. Box 857
Lemon Grove, CA 91946-0857
(619)460-3620
Horn

Getting the horn to work properly was the most perplexing part of the conversion. I tried several "voltage reducers" from the local parts stores but none could handle the current demands of the Model A horn. I finally purchased a 0 to 2 Ohm variable power resistor with a 100 watt rating from an electronics supply house. I selected a variable resistor in order to optimize the voltage to the horn.
The resistor I purchased was am Ohmite D100K2RO ($15.87) with two Type 12 brackets ($0.55 ea.) (Newark stock nos. 13F671 & (2) 13F099) from:
Newark Electronics
1-800-463-9275
Branch offices of Newark are located throughout the United States. Minimum order is $25.00. An alternate approach would be to puchase a 12 volt horn.
Light Bulbs

The following bulbs can be used with a 12 volt system: Cowl, Tail, and Dash Lights - #89, 6 cp
Dome Light - #67/97, 4 cp
Stop Lights - #1156/10, 32 cp
Turn Signals

If you have a Signal-Stat turn signal it will be necessary to change the flasher to a Signal-Stat #180 and the bulb to a #1445.
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Old 07-09-2010, 04:34 PM   #11
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Default Re: Advice to change 6 volt to 12 volt Model A

I use 12 volts because with halogen lights you only have half the amps going through your wiring and switch. Easy on the whole system.As mentioned Les Andrews book is helpful(both).
Good luck,John
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Old 07-09-2010, 04:58 PM   #12
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Default Re: Advice to change 6 volt to 12 volt Model A

I fruitlessly attempt to get people to ask why they really need to convert.

It is a well established fact that there are very good 6v halogen bulbs. When installed and properly focused with original headlamp parts they give you the light you need to run 55 mph at night. These bulbs use about the same current as the factory bulbs so they work with the factory system.

People seem to ignore basic alt install principals. Most alt will not come close to giving you their rated max amps. This is because the belt and pulley system is not capable of supporting this.

The list goes on.

So in the end you have spent some $$$ and not really bought any advantage to a properly restored original system. You may have the illusion of an improved system, but is it really improved. The people selling these improvements have profited so I guess that is an improvement.
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Old 07-09-2010, 05:12 PM   #13
Freddie (Memphis)
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Default Re: Advice to change 6 volt to 12 volt Model A

Freddie (Memphis) posted...

Quote:
Wayne...careful, you may get more questions about "why would you want to change to a 12v system when a 6v works just fine" rather than answers on how to do it.

See what I mean...?

Guys...I'm sure Wayne appreciate your advice...really, I do. But, hell...it's not your car. If Wayne wants to convert it to 12v, then I'm sure he has his reasons...as I had when I converted mine...and you had when you decided to NOT convert yours. Did anyone try to convince you to leave your car(s) 6v...? I'd bet they didn't...

Listen to yourselves...you all sound like a bunch of ol' women cacklin' about how so-and-so shouldn't be seeing so-and-so... First thing you know, you'll be squabblin' about how you can't see any reason to change to a new format on Ford Barn..the old one worked fine for you and you never want to see it change..and if it does, you're going to start using the other Model A board...and so on and so on and so on. In fact...why did we ever stop using horses to get around on...or who needs to fly anywhere...or what do you mean...a device that shows movin' pictures sent over the air right in your own home...? Why pretty soon, we'll even be able to use a typewriter to send messages back and forth to each other over some kind of spiderweb thingie. Well...Goooo-oooo-leeee, Sergeant Carter, can yoo beleeve thet...?

Hey....wait a minute....

(...in good fun, guys...)
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Old 07-09-2010, 05:24 PM   #14
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Default Re: Advice to change 6 volt to 12 volt Model A

Why change?
Changing over is a pain.
Add an extra 1 gauge ground from the shifter case to the original battery ground strap on the frame. This will start your A in 1 turn of the key.
Pick up a 6v NuRex alternator for plenty of juice to spare.
Easy swap
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Old 07-09-2010, 05:26 PM   #15
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Default Re: Advice to change 6 volt to 12 volt Model A

Freddie Memphis, I agree with all that you said.
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Old 07-09-2010, 05:35 PM   #16
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Default Re: Advice to change 6 volt to 12 volt Model A

Mike V, Still what I said. You just wasted your time typing if you thought you would change my mind. We are free to make whatever mods to our model A that we see fit. Most are not asking for a hand out. I pay for my mods and I will continue to make whatever mods that I see fit.
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Old 07-09-2010, 07:17 PM   #17
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Default Re: Advice to change 6 volt to 12 volt Model A

It seems like more folks are getting all worked up over this than Wayne is.. I think he explained things early into this thread..
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Old 07-09-2010, 07:43 PM   #18
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Default Re: Advice to change 6 volt to 12 volt Model A

Kevin in NJ , I agree that there are some Good halogen bulbs that will work with the model A generator. I have a set of these bulbs in my roadster that I run 12 volts with the original generator. These bulbs are much better than the old 50 candle power bulbs but don't come close to the quartz halogen bulbs, I have No illusion, its just common sense.

It doesn't really matter if the alternator or generator actually charges 60 amps. If the modern bearing and sleeve are used on the water pump the belt CAN be tightened as necessary. I have run a 60 amp alternator with quartz halogen bulbs in my 31 coupe for over 15 years with No problems and the lights are as bright as modern cars. Many cars run 60 and even 100 amp alternators and they never have to charge maximum charge rate. The alternator will only charge enough to meet the demand. The quartz halogen bulbs actually don't draw 60 amps. Have you ever heard of reserve power? That I believe is why some want a 60 alternator. With a few MODS the model A generator can be brought up to 60 amp capability.

Why waste your time trying to tell other people how they should run their model A . People will pretty much do as they please. If you are such an expert on all things concerning model A's why don't you go ahead and finish your model A.
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Old 07-09-2010, 08:16 PM   #19
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Default Re: Advice to change 6 volt to 12 volt Model A

Purdy I do not believe you have read my posts very well.

I am not telling anyone how they should run their cars.

I am just pointing out the facts behind the conversions so that one can make a choice based on facts. If you take some time to read what I actually say you will find I am not telling him to not do the conversion. Instead I am giving him verifiable facts to base a sound decision before he decides to make changes to his car.
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Old 07-09-2010, 08:49 PM   #20
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Default Re: Advice to change 6 volt to 12 volt Model A

Quote:
Originally Posted by Purdy Swoft View Post
Mike V, Still what I said. You just wasted your time typing if you thought you would change my mind. We are free to make whatever mods to our model A that we see fit. Most are not asking for a hand out. I pay for my mods and I will continue to make whatever mods that I see fit.
While I question the reasons to ensure that the request is not based on misinformation and while I don't like changing a Model A just for the hell of it I will will try to give an answer to the question. Do I always succeed no but I try.
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