Oct 8, 2011
The rule that makes 12-volts work so well is the one that says if you double the voltage, the amperage required to power that same accessory is reduced by half. For example, the original 6-volt motor requiring ten amps of electrical current would only need five amps of electrical current to run at the same speed. So with this, the total load for the Model A with the lights on running at night and trying to blow the horn would only be half as much with a 12-volt system as with a 6-volt system.
Six-volt electrical systems use heavier gauge wiring to deliver the higher amperage draw. Therefore the wiring does not have to be changed when converting to 12-volts. Also the windings in the starter and horn are also heavier due to the amps used in a six-volt system.
If you are still using a six-volt generator it can be converted to 12-volts. You will need to have the field coils (magnets) replaced. These are the magnets that are attached to the inside of the generator case. This is a job that can be handled by any qualified alternator/starter repair shop. You will then need a 12-volt regulator. Just ask for a 1956 or newer 12-volt regulator to match your application.
Alternators were first introduced in the early 1960’s. By the 1970’s alternators were being built with solid-state internal regulators. This improved the reliability of vehicle charging systems. The biggest difference between an alternator and a generator is that an alternator is able to produce a strong electrical output at idle and low rpms. This makes the headlights bright all the time, and provides a way to keep the battery fully charged at all times.
An alternator generates electricity just the opposite way a generator does. Inside an alternator, the armature remains stationary while the field coils rotate. That makes the alternator able to spin up to 10,000 rpms before suffering any internal damage. Therefore a smaller pulley can be used on an alternator to keep the rpms up while idling.
The best alternator to buy is a General Motors 10SI series alternator. You will want to have the alternator made into a single wire alternator. These alternators are also available through your Model A vendor.
You will have to change all your light bulbs to a 12-volt lamp. This will make the lamps you use a standard lamp available at your local automotive store. This convenience will help eliminate the amount of parts that you will need to carry.
Your Model A was built with a positive ground system. This means that the negative (-) terminal of your battery is connected to the starter terminal and the positive (+) side of the battery is connected to ground. In order to use the above modern alternator on 12-volts, you will need to reverse the polarity. When this is done, you will also need to reverse the wires on the amp gauge in the dash and the coil.
The ignition coil will either need a resistive ballast added to the incoming power or my recommendation is to buy a coil with an internal resistor. Internal resisted ignition coils are much more reliable and will eliminate a common trouble spot, the external ballast resistor. One coil that you can get is a NAPA Echlin PT# IC64. Remember that this coil needs no external resistor.
Last but not least, you will need a 12-volt battery. Make sure to measure your battery box, so you can get the right dimensions for your new purchase. I would recommend that you find one with the cold cranking amps close to the six-volt battery. Happy driving.
This tech tip was published in the March/April 2002 “A” Quail Call.
Oct 1, 2011
A battery has 100% of rated capacity at 80 degrees F. At 0 degrees F, the same battery has only 40% of the capacity (Amp Hours) it had at 80 degrees. At 40 degrees, the starter requires over two times as much energy to turn the engine over as it did at 80 degrees.
This tech tip was originally printed in the Jan/Feb 2002 “A” Quail Call.
Sep 24, 2011
In the spring of 2001, I finished the restoration on my Town Sedan and found I was ready for a test trip. I called my niece, who lives about 40 miles from me, and told her I’d pick her up for lunch.
A few miles into the trip my hands were cold. I pulled over to find my gloves. The engine stalled, so I hit the starter. Uh oh, it locked up.
I tried it all, in gear rocking, drifting downhill popping the clutch and even cursing, but no dice. Pull the starter. Yeah, right. With all of the bolts out, I rocked the car. That starter was not coming out. Finally using a pry bar, the started popped free with a loud snap. I reassembled the starter and finished my luncheon trip without any notice.
The rest of the summer, I noticed a slight tic, tic, tic. It drove me crazy. I dropped the pan and plasti-gauged all the bearings. I pulled the pistons and used the micrometer on them and the bore. No good.
People would say “What’s that ticking?” Embarrassed, I’d say “piston slap,” not knowing for sure what it was.
To make a long story shorter, I found it. Yep, that locked up starter caused it. When I pried the starter free, it moved the starter ring on the flywheel. Just 1/8″, not much but enough to touch the bottom starter bolt for about 2” every revolution. The only time it touched was when the clutch was depressed. This pushed everything up tight against the thrust bearing.
Tic, tic, tic.
Editor’s note: It’s really quite ironic how and when articles come to us. This item was e-mailed to us one evening just as I came into the house from working on one of our Model A’s. When I read this tip, I immediately felt relieved to learn that this was the solution to the problem that I was experiencing.
This tech tip was originally provided by AJ Pennington and printed in the May 2002 “A” Quail Call.
Sep 17, 2011
Although I have not been involve with Model A’s as long as many have, I have heard horror stories and seen some myself of what high temperatures in an engine can do. I have had both a temperature gauge and a reproduction motometer on my Town Sedan ever since I have owned it. Only once have I ever seen the red mercury show up in the motometer. That was when I had a problem with the radiator and the temperature gauge was spiking over 190 degrees. We quickly stopped the car to save the engine and let it cool down.
Even though I have heard the argument that many people ran the Model A’s for many of years without temperature monitoring devices, I find it difficult driving a car without a temperature gauge. One of the key indicators to me if an engine is OK is knowing the temperature range that the engine is running. When you install the temperature probe of the temperature gauge in the upper water neck or in the upper hose with the adapter pipe, the probe is always in the hottest water of the engine. This is a plus for the temperature gauge unless the system is dry; it should always be in the water stream.
A motometer can fail you at times if the water level becomes lower than the probe extends down. I have also seen where the mercury will divide and a false reading will occur. To depend on this form of information may create a whole lot of problems that may not really exist. As in my case, the motometer never shows any temperature until it is too late. By the time my motometer shows that the water is hot, I may have already created warpage of the engine head or worse, I have scored the cylinder walls.
With the cost of a temperature gauge, approximately $50.00, versus not having one and having to rebuild an engine, it is my experience that a temperature gauge is a small investment to protect the larger investment in an engine.
This tech tip was originally printed in the October 2001 “A” Quail Call.
