A. With the vibrators properly adjusted, if any particular cylinder fails or seems to develop only a weak action, change the position of the unit to determine if the fault is actually in the unit. The first symptom of a defective unit is the buzzing of the vibrator with no spark at the plug. Remember that a loose wire connection, faulty spark plug, or worn commutator may cause irregularity in the running of the motor. These are points to be considered before laying the blame on the coil.
Q. How may short circuit in commutator wiring be detected?
A. Should the insulation of the primary wires (running from coil to commutator) become worn to such an extent that the copper wire is exposed, the current will leak out (i. e., short circuit) whenever contact with the engine pan or other metal parts is made. A steady buzzing of one of the coil units will indicate a “short” in the wiring. When driving the car the engine will suddenly lag and pound on account of the premature explosion. Be careful not to crank the engine downward against compression when the car is in this condition, as the “short” is apt to cause a vigorous kick back.
Q. Does coil adjustment affect starting?
A. Yes. When the vibrators are not properly adjusted more current is required to make and break the contact between the points, and, as a result, at cranking speeds you would not get a spark between the spark plug points. Do not allow the contact points to become “ragged,” otherwise they are apt to stick and cause unnecessary difficulty in starting, and when running they are apt to produce an occasional “miss” in the engine.
Q. What is the purpose of the commutator?
A. The commutator (or timer) determines the instant at which the spark plugs must fire. It affects the “make and break” in the primary circuit. The grounded wire in the magneto allows the current to flow through the metal parts to the metal roller in the commutator. Therefore, when the commutator roller in revolving, touches the four commutator contact points, to each of which is attached a wire connected with the coil unit, an electrical circuit is passed through the entire system of primary wires. This circuit is only momentary, however, as the roller passes over the contact point very rapidly and sets up the circuit in each unit as the roller touches the contact point connected with that unit. The commutator should be kept clean and well oiled at all times.
Q. What about the spark plug?
A. One is located at the top of each cylinder and can be taken out easily with the spark plug wrench included with every car, after the wire connection is removed. The high voltage current flows out of the secondary coils in the coil box and on reaching the contact points on each spark plug it is forced to jump 1⁄32″ gap, thereby forming a spark which ignites the gasoline charge in the cylinders.
The spark plug should be kept clean (i. e., free from carbon) and should be replaced if they persist in not working properly. There is nothing to be gained by experimenting with different makes of plugs. The make of plug with which Ford engines are equipped when they leave the factory are best adapted to the requirements of our motor, notwithstanding the opinion of various garage men to the contrary. All wire connections to spark plugs, coil box and commutator should, of course, at all times be kept in perfect contact.