Mar 17, 2012
There has been a lot of discussion about which is the best fan to keep that Model-A temperature the coolest. Is the original 2-blade metal fan, the later 4-blade metal fan, or the aftermarket 6-blade plastic fan the best?
For this test a sophisticated instrument was used to measure the air speed in MPH (Miles Per Hour) at three different engine RPM’s (Revolutions Per Minute). The results are not scientific but do give a good indication of which fan produces the most airflow. The tests were performed on a stationary vehicle. The following tests indicated the fan air flow MPH speeds with engine speeds of 500 RPM, 1,000 RPM, and 1,500 RPM. The measurements were taken at the front right corner of the engine block.
Engine @ 500 RPM Engine @ 1,000 RPM Engine @ 1,500 RPM
(12 mph ground speed) (25 mph ground speed) (37 mph ground speed)
Fan Air Flow Air Flow Air Flow
2-blade 7 mph 18 mph 25 mph
4-blade 11 mph 24 mph 32 mph
6-blade 8 mph 22 mph 34 mph
The above Air Flow test results indicate:
1) The 2-bladed fan produces less air flow than either the 4-bladed or 6-bladed fan.
2) The 4-bladed fan produces the most air flow up to 1,000 rpm.
3) The 6-bladed fan produces the most air flow at 1,500 rpm and higher.
Summary: The 2-blade fan should be adequate if the cooling system is up to par. If not, more fan blades might be needed. A cars higher speed will increase airflow through the radiator, but also increase engine heat. Remember, a good clean radiator, correct coolant, and a tight fan belt are essential to good Model-A cooling.
This article was authored by Marvin Melage with data provided by the Model A Times Magazine.
Mar 10, 2012
That is a question that has been kicked around the garage for some time now. The early thoughts were that a thermostat was needed to slow the water flow in the radiator. Extensive tests have shown that changes in the rate of water flow through the radiator results in negligible change in water temperature. A Model A radiator should cool the engine under normal driving conditions.
A good clean radiator, even a stock one, should keep the engine operating at a normal level (160-170 degrees). If your engine is running hot you should look at all of the things that could be cause. An older radiator, one that appears in good shape and flows well, may have deteriorating connections of the fins to the tubes, which reduces its ability to transfer heat to the surrounding air and is usually the cause of engines running hot.
The original design of the Model A radiator is for a Thermo-Syphon system used in conjunction with a water pump. The entire cooling system was engineered to use the best of both types of systems. The thermo-syphon system keeps the coolant in place until the engine reaches an operating temperature of around 180 degrees. The pump increases the flow of coolant when the engine is operating at higher speeds and the thermo-syphon system would not move the coolant fast enough to cool the engine. So the Model A was equipped to have a thermostat of sorts with the thermo-syphon system helping the engine warm up before the coolant started moving. This still doesn’t answer the question regarding installing a new thermostat. The modern fuel of today requires the engine to operate at above 160 degrees to burn clean and with the most efficiency.
Tests were made using a new reproduction radiator along with a high compression head. The Motometer temperature gauge (thermometer) on the radiator cap takes it’s readings through a special stud, mounted in the motometer. Through many operating conditions, the thermometer never rose to the operating range on the motometer. A modern temperature gauge with degree readings was then installed along with a temperature sensor mounted in the upper water outlet neck. After running the Model A through many operating conditions it was surprising to find that the newly installed temperature gauge never rose above 140 degrees on a hot summer outing. After seeing the engine operating so cold, a 160-degree thermostat was installed in the upper radiator hose. In a short period of time the engine water temperature now rises to 160degrees F as seen on the water temperature gauge. The opening and closing of the thermostat can be seen on the temperature. The gauge displays change as the indicated temperature rises to 170° and then drops to 160° as the thermostat opens and closes.
Installing a thermostat will allow the engine to operate at the most efficient temperature range, getting the most out of the fuel that is being used and at the prices we are being forced to pay you best get the most out of your money. This is an easy and beneficial improvement that will make your Model A operate at an efficient temperature level, allowing complete and proper burning of the fuel, thereby reducing unburned fuel and fuel contaminates that produce carbon buildup and sludge in the engine. The illustrated thermostat can be purchased from any Model A Parts Supplier in temperature ranges of 160° or 180°F operation. Installing a water temperature sensor in the upper water outlet neck and a water temperature gauge, will provide a more accurate indication of your engines operating temperature.
Mar 3, 2012
When the spark plugs are dirty, they demand a really good cleaning. You can take care of the job yourself by buying a bottle of household ammonia. Simply soak the plugs and they will emerge cleaner than sand blasted ones. The ammonia loosens the deposits and floats them away.
Feb 25, 2012
The ignition coil does not change the direction of current flow hence it does not change polarity. However, there are more coils in the secondary winding inside of the coil, thus there is more resistance to incoming current flow at the secondary winding terminal, so the coil’s high voltage output to the spark plugs will be less if the battery is inadvertently connected to the secondary winding terminal. By the way, the higher resistance wastes primary current in the form of heat and the coil will run hotter if the battery (current-in) is connected to the secondary terminal instead of the primary terminal. Heat reduces coil life!
So now that we know the primary terminal on the ignition coil is where we want to connect the battery wire, two questions arise to get the connection right in the Model A: (1) Which is the primary terminal on the coil? (2) Which is the correct wire from the battery that connects to the primary terminal?
(1) Using an ohmmeter with one lead in the high voltage output socket, measure the DC resistance at each wire terminal. Connect the battery wire to the terminal with the least resistance to get the highest secondary voltage output to the spark plugs.
(2) Assuming that the Model A has a 6-volt system wired in accordance with the factory diagram, the BLACK wire from the driver’s side of the terminal box is the correct wire. If your Model A has non-factory wiring, then find the wire coming from the CHARGE side of the ammeter and trace it down to the terminal box stud. Connect this stud to the primary terminal of the coil.
Do not rely on the markings that may be cast into the coil top at the terminals. Before 1955, coils were marked (-) or BAT at the primary winding terminal, and (+) at the secondary winding terminal because the ignitions of the time were 6-volt (+) ground. By 1956, ignitions went to 12-volts (-) ground, so the primary terminal was marked (+) or BAT. So you can see the coil markings may cause you to make the wrong connections for a pre-1956 Ford.
If you find the above confusing, here is a much simpler solution. Buy from your local Model A parts supplier, a gizmo known as a “Ignition Spark & Coil Tester.” It costs in the ballpark of $25, and it has lights to indicate if the wiring is right or wrong. This gizmo will earn its price back in gasoline mileage and performance.
Most all coils, 6 and 12-volt alike, for breaker point ignitions are (the same) designed for 6 to 8-volt operation. Note the resistance wire in the figure. In a 12-volt ignition system, the ignition switch has 2 run positions. The START position allows 12 volts into the primary coil to get a hot shot high-voltage engine start. When you release the key to the RUN position, the resistance wire is cut into the primary circuit to drop the coil voltage to 6 to 8 volts. The heat from a constant 12-volt input will shorten the life of a breaker point ignition coil.
When converting from 6 to 12-volt operation, you can run a reproduction “Ford” script 6-volt coil with an external resistor so the coil operates at 6 to 8 volts. You can also run a 12-volt coil with an external resistor. However, some 12-volt coils have an internal resistor and you need to know this to avoid having two resistors on the primary side of the coil.
Running an antique ignition coil is fool hardy because eventually coils breakdown and cease to function without warning. Do not run an original antique coil in a 12-volt conversion because these old coils will not take the stress of 8 to 12 volts. Also make sure that the brass terminal ends are soldered to the conductor of the high-voltage wire between the coil and the distributor. Keep the primary wire connections bright & tight and the plastic parts of the coil and distributor clean.
Feb 18, 2012
Will a loose ball in the front wishbone at the transmission cause a shimmy? Yes, this could be one of the issues causing a car to shimmy. A loose ball in the front wishbone can be one of the causes of front shimmy. The front end caster (5 degrees) is dependent on the exact position of the front radius ball. Make sure you have all the correct pieces to mount the radius ball to the bottom of the flywheel housing. It should consist of an upper and lower cap, two spacers that fit through the mounting holes in the lower cap, two springs and two castle nuts. If the assembly is correct and the ball does not fit tight, purchase or make a shim out of a thin fender washer, pounded to fit around the top half of the radius ball and reinstall the cap assembly. Then measure the front end caster. Also make sure the tie rod balls are round and the drag link ends are screwed in tight enough — check Les Andrews Mechanics Handbook for specific settings. Toe-in should be 1/16″ to 1/8″. Also make sure the mounting bolts for the steering gear box are very tight. Worn king pin and/or bushings can contribute as well. All these things relate to front end shimmy. The most over looked and cause is incorrect front end caster adjustment. This is determined by the position of the radius rod ball.
