1942 - 1947 Chevrolet Shop Manual



	*6-32*

	Ignition Distributor The ignition distributor is designed to operate with a polarity reversing switch which reverses the polarity or direction of current flow, through the distributor points thereby greatly lengthening their life. The breaker plate is completely insulated from the distributor body by a strip of insulating material extending from one distributor cap clamp location to the other. The screws attaching these clamps to the distributor body are screwed into nuts made of insulation material located inside the breaker plate lugs. One primary terminal is located in the distributor body and insulated the same as on former models; the other primary terminal is insulated from the distributor body and screwed into a lug on the breaker plate. The breaker cams have a steep angle, insuring that the breaker points remain closed for the greatest number of degrees of cam rotation, thereby permitting current to flow through the primary winding of the coil a greater length of time. This results in greater magnetic saturation of the coil which in turn increases the coil output of secondary current. Fig. 67 shows the ignition distributor.	the trouble corrected. See instructions for this operation in Section 12 of this Manual. Examine the distributor points. Dirty points should be cleaned, and pitted or worn points should be replaced. Check the points for alignment, and align them if necessary. Hand-crank the engine until the distributor point cam follower rests on the peak of the cam. Adjust the point gap to .018", using a feeler gauge. This operation must be performed very accurately because it affects the point dwell or length of time the points remain closed in operation and, in turn, ignition coil performance. Hand-crank the engine until the cam follower is located between the cams. Hook the end of a distributor point scale over the movable point and pull steadily on the spring scale until the points just start to open. At this point the reading on the scale should be between 17 and 21 ounces. Check to see that the vacuum spark control operates freely by turning the distributor body counterclockwise and see that the spring returns it to the retarded position. Any stiffness in the operation of the vacuum spark control will affect the ignition timing. Ignition Timing Set the octane selector at "O" on the scale, Fig. 68, and attach a Neon Timing Light to No. 1 spark plug. Start the engine and run it at idling speed. Loosen distributor clamp and rotate the distributor body clockwise and counterclockwise until the steel ball in the flywheel lines up with the pointer on the flywheel housing. Tighten the distributor clamp screw.


	Fig. 67—Ignition Distributor Remove the spark plug wires from the distributor cap and examine the terminals for corrosion. The wires should be checked for damaged insulation and oil soaked condition. Remove the distributor cap. Check the cap and distributor rotor for cracks or burned contacts. Check the distributor automatic advance mechanism by turning the distributor cam in a clockwise direction as far as possible, then release the cam and see if the springs return it to its retarded position. If the cam does not return readily, the distributor must be disassembled and the cause of
		Fig. 68—Octane Selector Reassemble the distributor cap and spark plug wires. Make sure that all terminals of the primary wire at the ignition coil, reversing switch and distributor are clean and tight.