ATWATER KENT IGNITION SYSTEMS
CONSTRUCTION, OPERATION AND CARE
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.
[Illustration:
CONTACT
MAKER
TO PLUG
TO PLUG
DISTRIBUTOR
CONDENSER
TO PLUG
CONTACT MAKER
GROUNDED
SPARK PLUG
BATTERY
GROUND
PRIMARY
BATTERY
GROUND
SWITCH
SECONDARY
GROUND
REGULATING
RESISTANCE
Fig. 66. Atwater Kent Circuit Diagram--Type CC]
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.
[Illustration: Fig. 67. Atwater Kent Contact Breaker--Type CC]
[Illustration: Fig. 68. Atwater Kent Distributor and Contactless Block]
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.
[Illustration: Fig. 69. Distributor Wire Connections to Distributor]
=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.
[Illustration:
TO UNGROUNDED
TERMINAL OF BATTERY
SWITCH
COIL
DISTRIBUTOR
GROUND
CONTACT
MAKER
Fig. 70. Atwater Kent Type CC Wiring Diagram]
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.