The Model T was designed to be simple and cheap. In 1927, when this car was built, many other car manufacturers were adding more sophisticated parts and designs to their cars. The new "Improved" Model T was introduced in 1926 in an attempt to spur sales of Model Ts and be more competitive. However, sales continued to fall and, in 1927, the Ford car factories shutdown in order to re-tool for the introduction of the Model A.
Some of the simple design features of the Model T are:
1) no oil pump. All the oil is circulated through the
engine by the splash of various components. Lawn mower engines are still made
this way today.
2) no
water pump was installed on the engine. The water circulated in the engine using thermo syphon, where
the hot water rose to the top and was then cooled by the radiator to circulate again.
3) no fuel pump. The fuel arrived at the carburetor by
gravity feed. Earlier Model Ts have
the gas tank under the front seat; there is not much slope for the fuel to drain to the carburetor.
This is why you hear stories of people backing up hills in a Model T. The fuel will run toward the
carburetor and they get a lower gear in reverse. In this "Improved" model, the fuel tank is mounted up high in the
cowl area to avoid fuel starvation on steep hills. The filler is through the vent on the cowl.
This car is equipped with a Ford accessory "Hill and Dale" external oil line. This gives the engine a second method of getting oil to the front of the engine. This system uses a specially cast transmission inspection cover that has a scoop for collection of oil splashed by the flywheel, magnets and transmission parts. The oil is collected and routed through a copper tube to a hollow bolt that goes through the front cover of the engine. This oiling method is in addition to an internal oil line that also routes oil from the transmission to the front of the engine.
The transmission on the left with the "hogs head" removed. The "hogs head" is just the cover for the transmission
which contains the pedals. In this picture, the reverse, first gear and brake bands are wrapped around
their respective drums and are wired to stay in place. Just in front of the transmission bands are the
flywheel and magneto.
The transmission of this "Improved" Ford has a wider brake band for more stopping power and removal band ears ease the replacement of the bands. The additional width of the brake band is very important because this single transmission band is the main service brake for the car. The rear wheel brakes are only activated by pulling on the emergency brake handle. The safety of this particular car was improved in 2006 by adding some additional connections to allow the activation of the rear brakes when the main service brake pedal is depressed. See the brake page for more information. When the car was originally purchased, I was able to drive it, but only after replacing the transmission brake band. During the engine and transmission rebuild in 2006, all the bands were changed out to new kevlar bands.
When the engine was torn down for a rebuild in 2006, the rod bearings were nearly gone. The front two rod bearings had been wearing heavily on one end. This can occur when the crank has not been correctly machined to allow the rods enough movement when the crank shaft changes length with the severe heat. The main bearings were also worn, but not as severely as the rods. The cylinders were tapered but not much. The new babbitt bearings and machining work was done by Ed Katzorke in Carson City, Nevada.
The engine in this car had been worked on in the past. Having been built in late 1926, the engine should
have been equipped with a "high" cylinder head. It was discovered that the original cast iron cylinder head
that was installed was a "low" head, from an earlier Model T. A new cylinder head was purchased for the car;
it is a "Z" head or a copy of an original accessory cylinder head with a revised combustion chamber shape and
higher compression. The head was purchased from Harlon Zajicek who advertises in the "Vintage Ford" magazine.
The "Z" cylinder head raised the power level of the engine and is one of the most effective performance
improvements for the car. You can see a more technical analysis by reviewing the information
from the
Oklahoma Model T club.
Notice the shape of the combustion chamber in the "Z" head on the right. This modified shape helps to
give the "Z" head more power than just the theoretical increase in compression ratio. The standard "Z"
head would increase the compression ratio to about 6.0 to 1.
When the engine was rebuilt, the deck or top of the engine block was milled. This milling along with the "Z" head
result in compression of 80-85 psi, or around 6.7 to 1 compression ratio. The "Z" head is aluminum and, to reduce
future problems, the internal water passages were coated with a sealant and a zinc anode is used in the radiator.
The camshaft in this engine had worn as much as .010 of an inch off some lobes. A new Stipe 280 camshaft was purchased along with all new adjustable valve lifters when the engine was rebuilt. There is some talk about this camshaft making a difference in performance. I ran the new "Z" head on the engine before it was rebuilt and noticed a significant difference in power. I don't believe the camshaft makes much difference, but it is probably much better than a re-ground camshaft.
The original car had a Holley "Vaporizer" carburetor installed. This type of carburetor would pull the gasoline by a portion of the exhaust manifold in order to heat up and fully vaporize the fuel. This, of course, did not help to increase the efficiency of the engine, but it was required because of the poor quality of the gasoline in the late 1920s. This carburetor needed to be rebuilt, it had lots of places for air leaks to occur. It also has a large diverter in the intake which effectively served to block the air flow but was probably meant to be adjusted for the viscosity of the fuel.
To improve the performance of the car, a new high-volume intake manifold from Chaffin's was purchased. This is a replica of the intake manifold used around 1913. Along with this new intake manifold, a rebuilt Holley NH camel back carburetor was installed. These two features allow the engine to run at a higher RPM. It performs much better.
On the left is the original Holley Vaporizer after it was cleaned up and running.
On the right is the Holley NH carburetor with the aluminum intake manifold. This is a good picture showing
the rest of the engine compartment after it was rebuilt and re-painted. The final carburetor choke wire
and mixture adjustment rod are not in the correct place in this photograph.
The original radiator in the car had 4 rows of round tubes and appeared to be in good condition; it was cleaned, pressure tested, and repaired. However, when the engine was actually running, the car would tend to over-heat. It would not completely boil over, but it would blow steam when the engine was stopped. After trying various other potential solutions, a new BrassWorks flat tube radiator was purchased for the car and the over-heating is no longer a problem.
During the process of trying to utilize the round tube radiator, a new water pump was installed on the car, but Ford never put a water pump on these cars! This car has had a water pump as long as Uncle Arne can remember. The water pump is one of the most common accessories for the Model T and may have helped in the days of the original round tube radiators. Reportedly, the cooling fins do not make good contact with the round tubes after many years of usage and eventually the round tube radiators won't keep the car cool. The flat tube radiator is reportedly twice as efficient as the round tube at rejecting heat.
Another interesting difference with this engine was the fan pulley. As purchased, this car has a long nose fan pulley on it. This pushed the fan right up next to the radiator and, depending on how you pushed around the radiator, the fan would hit it. After some research and reviewing various pictures I realized that the fan was turned around backwards on the engine and that it should have a short nose fan pulley installed. It appears the fan had been turned around to allow enough clearance for the radiator with the long nose pulley. After changing the pulley to a short nose and putting the fan on the right direction, things fit much nicer. You might think that these changes would impact the cooling, but to no avail. The engine still over-heated until the new Brass Works flat tube radiator was installed. However, during the engine rebuild there was a lot of debris cleaned out of the engine block and cylinder head. The original radiator might be adequate for a clean engine.
The car retains the original electrical system with the exception that it has been upgraded to 12 volts instead of the original 6 volts. This upgrade is rather simple and involved the installation of a new cutout and installation of the higher voltage bulbs. Instead of the original cutout on the generator, there is now a new voltage regulator which appears to look like an original cutout. There have been several other enhancements to the electrical system in the car. Additional stop lights and turn signals have been added to increase the safety when in heavy traffic with modern cars dashing around you. The lights are added in the back of the car just under the trunk so they are not too obvious and can be removed easily for car shows. The turn signals on the front attach to the radiator bolts so they can be quickly removed for car shows. The turn signal level is a custom built box (with LED indicators for when the turn signals are flashing) and is bolted to the steering column with a formed metal strap similar to the horn button. It was done in this way to make it look as original as possible and still have the turn signal functionality.
The additional stop lights and turn signals are both new LED and incandescent lights. The LED lights were used to minimize the impact on the small electrical charging system of the car, but it was discovered that the turn signal flasher will not work on the low current draw of just LED lights. The incandescent lights were added to increase the current draw through the flasher.
According to Uncle Arne, this car originally had the wooden wheels, even though
it was manufactured in late 1926 when many of the cars were coming out
with wire wheels. Two of the original wooden wheels (21 inch, split rims) appeared to be in good condition. The spokes were
tight and showed no sign of deterioration. These two wheels were cleaned up and used on the car until August 2007. The
wooden spokes in the other two wheels were replaced in 2000. The spokes
on the first two rebuilt wheels are made of oak, but hickory was the
original wood specified by Ford. Now, all the spokes are natural wood color. After taking a mountainous tour,
the two original wheels were clicking, indicating loose spokes. The spokes in the second two wheels were subsequently replaced
with hickory spokes.
The car never had bumpers on it and, according to Arne, the split wheel rims were never silver colored or cadmium plated in appearance. Reportedly, the original cadmium coating would quickly turn a dark color.
Currently, the car still has old tires on it. These tires came with the car and are probably 30+ years old. The rear tires are what Uncle Arne called "snow tires". You can see the large knobs for the tire tread pattern in the picture to the right. Uncle Arne used these tires on his Model T truck during the winter when he collected and sold fire wood from the Sierra Mountains near Yosemite National Park. On these trips to get firewood, Uncle Arne drove a Model T truck up and down Priest Grade, which is 2 miles long and varying between a 14 to 20% grade! His mother insisted on coming with him, because she was so afraid of Priest Grade!
The front axle has been rebuilt with new bushings and pins. As of Sep 2007, the rear axle is the only part of the car that had not been rebuilt. The plan is to purchase a Ruckstel axle kit and rebuild the existing rear axle into a 2-speed Ruckstel, (See chronology of change section, with Ruckstell installation details). The Ruckstel axle helps when climbing hills. The first gear in the Model T is rather low and top speed is around 18 mph with stock 1 to 3.63 gearing, while second gear will take you up to 50 MPH. There is a big difference in gear ratio between 1st and 2nd. The Ruckstel gives you one more gear in between that allows for faster speeds on hills.
The car had a trailer hitch on the back that attached to the bolts that hold the rear spring. The hitch was used to pull trailers around the farm in the 1940s. You can tell that this car was heavily used on the farm. The right or passenger side of the car had holes drilled in the fenders and dents in the fenders indicating that long metal bars were added on the outside of the fenders and that chains, ropes and other farm tools were thrown on the right side of the car. The trunk lid was used in the same way. It was completely caved in, all the way to the bottom of the trunk.
At one time, Bonnie had a
working speedometer. You can see the drive on the inside of the front
left wheel. The drive is the plate attached to the back of the wheel with
a series of square notches. Originally, there was a corresponding gear attached
to a special arm on the steering gear. This gear drove a mechanical cable
up to the actual speedometer in the dash. The original odometer had
46,000 miles on it at the time it was purchased. The speedometer was
an AC speedometer and appears to be a dealer-installed option. The dash
was just cut with a saw and bent out of the way to make
room for the speedometer housing.
The original speedometer in the car was an "AC" brand speedometer. There were no drive gears or
cables for the speedometer and Uncle Arne cannot remember when the speedometer ever worked. An attempt was made
to get the AC Speedometer repaired, however, the main internal portions of the speedometer are made of "pot metal"
and deteriorated over the years. Speedometer repair people don't want to work on the AC and recommend using
another type of speedometer.
Consequently, a bicycle speedometer has been added to the car to keep track of mileage
and to give a better idea of the speed.
The wheel sensor is on the left front wheel where the original speedometer was located. A magnet was epoxied
to the end of a bolt and attached to the original speedometer ring.
On the
inside of the car the goal was again
to keep the look as original as possible. An AC
Speedometer head was modified with a new face plate such that
the bicycle speedometer would fit behind the face plate. A button attached to a shaft under the speedometer allows
you to operate the different functions of the speedometer.
| Table of Specifications | |||
|---|---|---|---|
| Equipment | Specifications | Description | |
| Engine - Crankshaft | Main bearings ground .020 inch
Rod bearings ground .020 inch | The crankshaft is a late model 1927 crank that was ground during the rebuild of the engine in 2006. | |
| Engine - Cylinders | Engine was bored .020 inch over standard. New aluminum standard compression pistons installed with new rings. | Rebuilt rods were purchased with babbitt bearings installed. The boring and valve work was done by Ed Katazorke in 2006. | |
| Engine - Cam and Valves | A new Stipe 280 cam, with adjustable lifters and small block Chevy values. New cam bearings and cam gear. | The Chevy style spring retainer clips are used with new valve springs. The front cam bearing was machined shorter, because the cam was machined as an early cam with a longer front lobe. | |
Bonnie 1927 Model T Ownership History Car History Brakes Chronology of Change Travels in Bonnie Other Projects
Updated July 22, 2009 David Harrison
References: Old Priest Grade