The Atwater Kent Ignition System


| June/July 1985



6 Windward Dr. Severna Park, MD 21146

This excellent ignition system is unlike most ignition systems using a coil, distributor and battery; thus, one must pay careful attention to the manufacturer's instructions if damage is to be avoided. The system basically consists of a special distributor and special coil. The distributor is called the 'UNISPARKER'. This name apparently was derived from the Latin 'uno' meaning 'one'. The 'UNISPARKER' makes one spark for each distributor point closure. In this system the coil is specifically designed to work with the 'UNISPARKER'. It is not likely that the substitution of a conventional 6 volt automotive coil will prove satisfactory due to the extremely short time (DWELL) the 'UNISPARKER' points are closed. The points must not be set 'closed' if the system is to operate. The points should be set 'open' .010 to .012 inch, never closer. There are no other adjustments. The movement of the points is so fast the human eye cannot follow the motion. Don't file or grind the parts of the 'UNISPARKER' thinking you will get the points to move. The parts are hardened and should never need to be changed.

The 'UNISPARKER' was made in several versions. The type 'K-2' operated clockwise, only; whereas, the type 'H' (without automatic spark advance) was available for either clockwise or counter clockwise operation. It should be noted that only the specified rotation will provide correct operation with the 'UNISPARKER'. It will not operate in both directions, as a timer will, on a direct reversing engine. Note the direction of the notches in the shaft. The correct rotation of the shaft is in the direction that drags the 'lifter' in the direction the shaft is turning. As the shaft rotates, the 'lifter' will be forced off the shaft, bumping the 'latch', which closes the points so fast that it appears nothing happened. Placing a finger lightly on the point spring should reveal slight movement as the 'lifter' snaps back. One needs to insure that the parts, such as the 'notched' shaft, 'lifter' and 'latch', are kept clean and oiled regularly with a light weight oil. The manufacturer makes no mention of grease for lubrication; however, when the 'UNISPARKER' was designed in 1904, there may have been no suitable grease available. The 'lifter' spring tension is very light and oil is probably a totally satisfactory lubricant. The spring tension seems to be approximately 150 grams to cause the 'lifter' to just move toward the 'notched' shaft. The spring tension measurement is made with the distributor in its normal operating position ('notched' shaft in a vertical position). The gram gauge should be horizontal and in line with the spring. Perhaps the most significant point to be made in servicing the 'UNISPARKER' is that if you treat it like a fine watch it should give excellent service. The system is very conservative in battery power; and, even if the engine is stopped with switch 'on', no power is consumed, because the points are normally open.

The coil generally used with the 'UNISPARKER' is the ATWATER KENT SYSTEM TYPE-K. This model of coil also seems to be the one most often seen at flea markets and shows. The Type-K coil is approximately 8'L x4'W x 3'H. On the top there is an 'ON/OFF' switch and a contactor labeled, 'START'. The START contactor is used to start an engine, assuming it is at the right position in one of its cylinders and the last time the engine was stopped one remembered to choke the engine just before it stopped rotating. This will suck a charge of gasoline into the cylinders. Typically, an engine will start as much as twenty four hours later using the START contactor, provided the cylinders have a charge of gasoline.

On the side of the TYPE-K coil one will find six binding posts arranged as follows:

INT O O NEG 6