When I bought my first Packard in 1969, it was a "Clipper Eight." The Clipper series started in 1941 and ran through 1947. One of the features of the newly-designed car was accelerator-activated starting. You just turned on the key, depressed the accelerator, and the car started, eliminating the push button starter on the cars of the era. Not being aware of this at the time, it didn't bother me that someone had bypassed the system when it stopped working, and had installed a push button on the dash to start the car. They had left the correct WDO Carter carburetor with the starter switch mounted on it. When I began to restore the car, I wanted to change back to the original starting method. I sent the carburetor to Daytona Parts (386-427-7108) for rebuilding and switch repair. Then, using a wiring diagram, I removed the dash button and re-wired my carburetor switch. This unique system is relatively easy to rebuild.
Here's how it works: The starting switch is incorporated in the carburetors of all Clipper models, so that the starter can be operated by the accelerator. The carburetor throttle shaft has a milled groove into which rests a steel ball. A short passage in the carburetor casting connects the top of the ball passage to intake manifold vacuum so that with the engine operating, the ball is drawn up into the passage away from the shaft, making the switch operate. When the engine is stopped and the accelerator is depressed, the milled portion of the throttle shaft forces the ball against a plunger, which moves a bakelite guide and a contact spring (shaped like the letter W) up to make contact between the two brass contacts molded into the bakelite switch body. This completes the circuit for the solenoid switch on the starter, causing the starter to crank the engine. As soon as the engine starts, the manifold vacuum acts upon the ball and, when the accelerator is released and the throttle shaft returns to its normal position, the ball is drawn up by vacuum away from the shaft. The ball remains in the upper position as long as the engine is running. A coil spring is provided to return the plunger guide and contact spring, thus breaking the contact between the two brass contacts in the switch body. As long as the ball remains up, any future operation of the throttle does not make switch contact until the engine is stopped. The coil spring rests on a round washer with a square hole, which provides a seat for the spring. Switch contact should be made when the throttle is opened between 30 to 45 degrees. Brass shims between the bakelite guide and contact spring are provided to adjust or determine the point at which switch contact is made. Shims are added to make contact sooner and are removed to delay the contact.
Starting the car: When starting the car, its important to release the accelerator immediately when the engine starts. If its held down allowing the engine to race, all of the rich starting mixture could be drawn out of the manifold, stopping the engine because of the resulting lean mixture. If flooding occurs, it might be necessary to operate the starter with the accelerator fully depressed long enough to clean out the flooded carburetor. Never pump the accelerator!
Choke operation: The choke will come into operation when the accelerator is depresssed to the point of engaging the car-starter switch. When the accelerator is released, the fast idle will come into operation. The choke unloading mechanism, which automatically opens the choke valve when the throttle is fully opened, is the same as non-carburetor switch carburetors.
Its nice to take the mystery out of this system and have it working correctly. This type was used on Packards from '41 to '54, and Buicks with Carter carburetors from '40 to '54. (For the Stromberg system, see the Southern Wheels archives section at www.southernwheels.com).
See you next month. Enjoy your cars and keep 'em driving!