Atwater Kent ignition systems have been adopted of late by many prominent automobile manufacturers as a means of distributing or conveying electrical spark to the cylinders at the proper firing time.

This type of quick break distributing system has proved very efficient and dependable, and will usually outlast the life of the motor as there are very few moving parts, which eliminates troubles caused by worn parts getting out of adjustment.

This type of ignition system operates in much the same manner as the high tension magneto, and differs only in that the parts have been taken from the compact magneto case and distributed in other locations in separate units. As this type takes its current from the lighting and starting battery, it does not contain an armature or field magnets to manufacture the electrical force.

Fig. 66 illustrates the principles of operation of the type CC Atwater Kent closed circuit system, which consists of the unisparker containing the contact maker and distributor. The only moving parts are located in this unit. The coil consists of a soft iron core, with a primary and secondary winding sealed in an insulated tube or container. A resistance unit is located in the top and regulates the current automatically. The system is controlled by a switch located on the dash. The contact breaker shown in Fig. 67 consists of an exceedingly light steel contact arm. One end rests on a hardened steel cam which rotates one-half as fast as the crank shaft. This cam has as many sides as the engine has cylinders. When the contact points are opened by the movement of the cam the primary circuit is broken and produces a discharge of secondary high tension current at one of the spark plug gaps.

Fig. 68 shows the simple Atwater Kent contactless distributor. The high tension distributor of the Atwater-Kent system forms the top of the contact maker. Each spark plug wire terminates in an electrode, which passes through the distributor cap. A rotating distributor block takes the high tension current from the central terminal and distributes it to the spark plugs in proper firing order. The distributor block or arm does not make direct contact with the distributor posts. The current jumps the small gap between the distributor block and the terminal electrodes and does away with frictional wear resulting from actual contact.

Fig. 69 shows the method of connecting the high tension wires to the distributor; the insulation is removed, or the wire bared in a space 1¹⁄₄″ long. The removable terminal cover is pushed up on the wire as shown at A, the bared end of the wire is then passed through the hole in the secondary terminal as shown at B. The end of this wire is then twisted back on itself, for two complete turns as shown at C, so that the end will not project beyond the diameter of the insulation. The wire will then be tightly held when the terminal covers are screwed down as shown in Fig. D. Never use pliers to tighten these covers and do not solder the wires to the terminal posts.

Adjustment.—The only parts of this system that are adjustable are the contact points. These need to be adjusted only for natural wear. Do not adjust the points unless you are convinced, by trying everything else, that it is the points that need attention.

In making adjustments, note the following directions. The normal gap between the points should not be less than .005″, or more than .008″, the standard setting is .006″, which is about the thickness of two ordinary sheets of writing paper.

The contact points are made of tungsten steel, the hardest known metal. When contact points are working properly small particles of tungsten steel will be carried from one point to the other, which sometimes causes a roughness and a dark gray coloring of the surfaces. This roughness does not in any way effect the proper working of the points, owing to the fact that the rough surfaces fit into each other perfectly.

It should not be necessary to file or redress the points unless they become burned, due to some abnormal condition or accident. The dark gray appearance is the natural color of the tungsten steel.

Oilings.—A very small amount of ordinary vaseline or grease applied to the cam and a drop or two of oil applied to the cups every few weeks, is all the lubrication necessary. Do not get oil on the contact points, and wipe off any free oil or grease on the contact maker.

The springs in this system are set at exactly the right tension. Do not try to bend or tamper with them.

The wiring of the type CC ignition system is very simple, as shown in Fig. 70, and is known as the one wire with ground return method. Well insulated primary wire is used for the primary circuit between the coil and the ignition switch. The best quality of five-sixteenth inch secondary wire is used to conduct the high tension current from the coil to the distributor, and from the distributor to the spark plug.

Setting or Timing the Type CC System.—The piston in number one cylinder should be raised to high dead center, between the compression and firing strokes, the clamp which holds the unisparker should be loosened and the unisparker turned backward, or opposite the rotating direction of the timer shaft until the contact points commence to open. The spark occurs at the exact instant of the opening of the point.

After completing the electrical connection the current can be turned on, and the unisparker timed exactly from the spark at the plugs. For this purpose the plugs should be removed from the engine and laid on top of the cylinders.