The Model A

After years of pondering the idea, a few years ago I purchased a 1931 Ford Model-A. It’s a coupe, here’s a picture…

Since this is a deluxe coupe, it has some additional features such as a dome lamp, cowl lights, carpeting and additional pin-striping. All Model-As (built from ’28-31’) had black fenders, but several colors were available for the wheels and body – on mine the top is Elkpoint Green, the main body is Kewanee Green, and the wheels/pin-striping are Tacoma Cream.

What’s a Model A like? Well, it’s a relatively small and light car. They only weigh about 2300 pounds. They are powered by a 200 cubic-inch four-cylinder flathead motor with a one-barrel updraft carburetor. Claimed was 40 HP. The transmission is a three-speed, with no synchromesh in any gear. From the transmission, there is a torque tube to the rear axle. This is like a pipe (which contains the driveshaft) that bolts solidly to the rear axle, and pivots up behind the transmission, so there is only one U-joint. The torque tube couples the motor and differential together. The wheels are 19” x 4”, similar to the sizes used on old British motorcycles. The suspension has good shock absorbers – a hydraulic lever type that was unusual in the day for any car. The brakes are purely mechanical – a bunch of rods, levers and pivots tie everything together. If you go over bumps while pressing on the brakes, the pedal moves back and forth some too. There is a completely separate system for the emergency brake, which is comforting.

There is no heater, although the side windows roll down and the windshield tilts forward for effective ventilation when it’s hot. A period accessory was a little heat shield that went over the exhaust manifold, connecting via a small hose to a port in the passenger’s footwell. A little round door can be opened to let in the heat.

The instrument panel consists of a speedometer, odometer, fuel gauge and ammeter. Mine has a period accessory panel that adds oil-pressure and water temperature below the main cluster. Since the fuel tank is right behind the fuel gauge, when the fuel is more than about 5/8 full, you can see the fuel through a little window in the gauge.

Speaking of fuel, fire safety wasn’t the highest priority of the day. Inside the engine compartment is a fuel filter with a glass bowl, just above the exhaust pipe. In front of the exhaust pipe, just inches away, is the carburetor intake with no air filter.

The trunk is quite large on these cars (if you don’t have the rumble seat), and many cars (including mine) were equipped with an optional trunk – and I really mean a trunk, that attaches to a folding rack above the rear bumper. There is also some storage space under the seat.

Here’s the starting drill for a stock Model-A:

  1. Reach under the dash on the passenger side and turn on the gas. The gas tank is in the cowl and feeds the carburetor via gravity – if you leave the gas on and the float sticks or leaks, it all goes on the ground.
  2. On the left side of the steering wheel, move the spark advance lever up to the retard position.  The car has no automatic advance.
  3. On the right side of the steering wheel, move the throttle lever down a little to increase the idle speed once it starts. If it’s really cold, twist the choke lever about one turn counter-clockwise to richen the mixture.
  4. Turn on the ignition. When the key is turned, the switch pops out. The key can be removed then if you wish.
  5. Pull out the choke.
  6. Press the lever on the floor above the gas pedal, this actuates the starter.

Once it starts, quickly release the choke and advance the spark. Then as it warms up, you can slowly lower the idle speed with the throttle and lean the mixture by twisting the choke knob back to where it was. This all sounds kind of daunting, but in practice, the choke typically doesn’t need to be used (either twisting or pulling), simplifying things. And some of the changes I've made (see below) further simplify things.

How does it drive? Well, you need to be patient. With no synchromesh, you shift, very slowly, from first to second at about five MPH. Then from second to third at about 10-15 MPH. Double-clutching helps, as does a big pause between gears. To down shift, double-clutching with a blip of the throttle is a necessity. You need to plan braking in advance, as the mechanical brakes are slow to stop you. It happily cruises along at about 45-50. As you drive through back country roads, if there are no other cars around, you can easily envision that it’s the 1930s. It will reach higher speeds, up to about 60 or so, but what I’ve read suggests staying in the 45-50 range if you want your main bearings to last. This is about 2100 RPM, and the motor makes power from about 1000 RPM up to about 2500 RPM.

My car was fairly stock when I bought it. It had been converted to 12V negative ground, in place of the original 6V positive ground. This gives easier starting and better lights. Also the more modern alternator is much better than the earlier generator. There was no automatic regulation on the stock generator - there is a third pole that you manually set for the fixed charge rate. If you are not running the lights, it slightly overcharges the battery. If you are using the lights, it will drain the battery over time – not ideal. My car also has turn signals – none came on the cars originally. Another modification to my car was installation of a Model-B four-cylinder motor – these were made from ’32 – ’34, although most cars of that series had the new flathead V8. The Model-B four-cylinder motor is very similar to the Model-A motor, but has slightly bigger bearings, a little more oil pressure, and was reported to have 50 HP instead of 40, although dyno reports of the original Model-A motor show that the rated 40 HP was quite optimistic and no doubt the same with the B. The only differences that would change power were a slightly higher compression ratio (4.8:1 compared to 4.2:1) and a cam that is a little more aggressive. So, instead of a crusty 77 year-old motor, my A has a modern 76 year-old motor.

I decided that the gearing of the Model-A was too much of a restriction upon driving it with modern roads. Even to get out of a metropolitan area, short stints on the freeway are necessary, and 45-50 is not safe, or considerate to other drivers. To remedy this, I decided to upgrade to a transmission that had an overdrive gear. Here’s the story…

Model-A 5-Speed Conversion

The ignition systems of the 1920/30's required a fair amount of maintenance, and even when all tweaked in weren't very efficient, so I decided to improve that a little to make it more efficient and reliable:

Ignition System Upgrade

How about a little more power, cleaner running, and better gas mileage from a carburetor upgrade...

Model-A Carburetor Upgrade

How about brakes that could safely stop you in the event of an emergency...

Model-A Hydraulic Brake Upgrade

I've been asked a few times for the dimensions of the brake master-cylinder mounting system (with reversal lever) that I fabricated. So I've made a simple print with the dimensions of those parts. Be glad to email it to you upon request.


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