1955 Buick Ignition System Components

The 1955 Buick ignition system consists of the 1955 Buick ignition switch, 1955 Buick ignition coil resistance unit, 1955 Buick ignition coil, 1955 Buick ignition distributor, 1955 Buick spark plugs, and the low and high tension wiring. Electrical energy is obtained from the battery while cranking and during idle speeds, and from the generator at higher speeds. These supply circuits must be considered part of the ignition system.

  • 1955 Buick Ignition Switch. The 1955 Buick ignition switch has three positions; “LOCK”, “ON”, and “OFF”. When in the “LOCK” position with key removed, the ignition is turned off and the switch is locked. When in the “ON” position the ignition is turned on, and in the “OFF” position the ignition is turned off, with or without the key in place in either position.
    The 1955 Buick ignition switch has three terminals which are protected against unauthorized bridging by a metal shield attached to the steering column support. For connections to the 1955 Buick ignition switch terminals refer to the chassis wiring circuit diagram in Section 10-J.
  • 1955 Buick Ignition Coil Resistance Unit. The resistance unit (resistor) is mounted on the cowl near the 1955 Buick ignition coil and is connected in series between the ignition switch and the positive (+) terminal of the coil. The resistance unit limits to a safe maximum the primary current flow through the coil and the distributor contact points, thereby protecting the contact points during slow Speed operation when they are closed for longer intervals. It also protects against excessive build up of primary current when the ignition switch is closed with engine stopped and contact points closed.
    A separate contact in the cranking motor solenoid switch is connected directly to the positive (+) terminal of the ignition coil so that the resistor is bypassed during cranking operation. Elimination of the resistor overcomes the effects of reduced voltage due to the cranking motor drain on the battery.
  • 1955 Buick Ignition Coil. The oil filled ignition coil is mounted on the rear end of the intake manifold, adjacent to the 1955 Buick ignition distributor. The positive (+) terminal is connected to the ignition switch through the resistance unit, and is also connected to the contact in the solenoid switch which bypasses the resistance unit during cranking of engine. The negative (-) terminal is connected to the primary terminal of the distributor. The secondary (high tension) terminal is connected by a short cable to the center terminal in distributor cap. See figure 10-41.
    1955 Buick Coil and Distributor

    1955 Buick Coil and Distributor

  • 1955 Buick Ignition Distributor. The 1955 Buick ignition distributor is mounted on top of the engine crankcase at the rear end. See figure 10-41. It is driven clockwise directly from the camshaft through steel gears which are automatically lubricated by the engine oiling system. The gear thrust is upward against a special bronze thrust washer.
    The distributor is of the single contact type with an 8-lobe cam. High speed operation is obtained by an especially light contact breaker arm and a high speed cam. Maximum operating efficiency of the engine is obtained under all speed and load conditions by the centrifugal advance mechanism and the vacuum advance mechanism built into the distributor.
  • Spark Plugs. AC Type 44-5 spark plugs having 14 MM threads, short (3/8″) terminals, and gaps of .030″-.035″ are specified for all engines. Rubber boots cover the cable terminals at the spark plugs.
  • Radio Suppressor and Capacitor. A 10,000 ohm resistor is built into the distributor rotor so that it is unnecessary to install a suppressor on the high tension cable when a radio is installed. A capacitor is mounted on the side of 1955 Buick ignition coil and connected to the positive (battery) terminal of coil when a radio is installed. See figure 10-41.
    An additional capacitor must never be connected to the distributor terminal as this will cause excessive pitting of breaker points or engine missing.

1955 Buick Ignition Operating Circuits

To clarify operating principles as well as to simplify the process of tracing troubles, the parts of the 1955 Buick ignition system should be understood to provide two separate and distinct circuits, as follows:

  1. The Primary Circuit carries the low voltage current supplied by the battery or generator. In addition to these sources of electrical energy, the primary circuit contains the 1955 Buick ignition switch, ignition coil resistance unit, primary winding of the ignition coil, distributor contact points, condenser, and all connecting low tension wiring.
  2. The Secondary Circuit carries the high voltage surges produced by the 1955 Buick ignition coil, which result in high voltage spark between the electrodes of the spark plugs in engine cylinders. This circuit contains the secondary winding of the ignition coil, coil to distributor high tension lead, distributor rotor and cap, ignition cables, and spark plugs.

Cycle of Operation

When the 1955 Buick ignition switch is turned on and the distributor contact points are closed, battery or generator current flows through the primary winding of the coil and through the contact points to ground. This flow of current through the primary winding of the coil produces a magnetic field around the coil windings and thereby stores electrical energy in the coil.

When the contact points are separated by the revolving distributor cam, the primary circuit is broken. The condenser absorbs the current which tends to surge across the gap as the points separate, thereby producing a sharp break in the flow of current. If the flow of current were not sharply broken it would form an arc which would burn the points badly and would also drain away most of the energy stored in the coil. There would be insufficient energy left in the coil to produce the necessary high voltage surge in the secondary circuit.

The very rapid change in strength of the magnetic field when the primary circuit is sharply broken causes a high voltage to be induced in every turn of both the primary and secondary windings.

The high voltage surge produced in the secondary winding of the coil travels through the cable to the center of distributor cap, through the rotor to the adjacent distributor cap segment from which it is conducted to the proper spark plug by the 1955 Buick ignition cable. The high voltage surge jumps the gap between the insulated center electrode and the grounded side electrode of the spark plug, thus producing the spark required to ignite the charge in the selected combustion chamber of the engine.

As the spark appears at the spark plug gap the energy in the coil begins to drain from the coil through the secondary circuit, thus sustaining the spark for a small fraction of a second. During this interval the condenser discharges back through the primary circuit, producing an oscillation of the current flow in the primary circuit during the brief instant that is required for the primary circuit to return to a state of equilibrium. Note particularly that the 1955 Buick ignition condenser does not discharge until after the spark has occurred at the spark plug gap.

The sequence of action described above is repeated as each lobe of the distributor cam moves under and past the rubbing block on the contact breaker arm to cause the contact points to close and open.

Control of 1955 Buick Spark Timing

The timing of the spark with respect to piston position in the cylinder must vary in accordance with operating conditions if best engine performance is obtained. The 1955 Buick spark advance for obtaining satisfactory idling should be as low as possible. At high speed, the spark must occur earlier in the compression stroke in order to give the fuel-air mixture ample time to ignite, burn and deliver its power to the piston as it starts down on the power stroke.

Under part throttle light load operation, a smaller amount of fuel-air mixture (by weight) enters the cylinder so that the mixture is less highly compressed. Under this condition, advancing the spark permits fuller utilization of the fuel-air charge. During acceleration or on heavy loads (wide open throttle) the spark advance required to develop the maximum power of the engine is considerably less than that required for light loads.

Control of 1955 Buick spark timing to satisfy these constantly changing operating requirements is obtained in three ways, as follows:

  1. Initial, manual setting of distributor is made so that contact points open at a specified position of piston, as indicated by a timing mark on crankshaft pulley or balancer. See 1955 Buick Ignition Timing (par. 10-41).
  2. Centrifugal advance is governed by speed of engine. The centrifugal advance mechanism built into the distributor consists of an advance cam which is integral with the distributor cam, a pair of advance weights, two springs, and a weight base plate which is integral with the distributor shaft.

At low Speeds the springs hold the advance weights as shown in figure 10-42, view A, so that there is no additional spark advance and the spark occurs in accordance with the initial manual setting of distributor. As speed increases, centrifugal force causes the advance weights to throw outward and push the advance cam, thus rotating the distributor cam ahead of the distributor shaft. This causes the distributor cam lobes to open and close the contact points earlier in the compression stroke so that the spark is advanced. See figure 10-42, view B.