1942 - 1947 Chevrolet Shop Manual



	12-25

	Second, as the engine is speeded up, centrifugal force begins to throw the governor weights (inside of the distributor body) outward, until at a maximum speed, they reach the point shown in the right-hand sketch of Fig. 53. In their outward		2. Remove the breaker arm and condenser lead from the primary terminal and remove the terminal from the distributor body. 3. Remove the other primary terminal and the screws retaining the breaker plate in the distributor body (same screws attach cap springs). 4. Drive out the pin retaining the distributor gear on the shaft and remove the distributor and advance mechanism assembly from the distributor body. 5. Remove the governor weight springs. Bend back the tangs on the lock plates and remove the two nuts holding the advance mechanism cover and remove the cover. 6. Remove the cam and governor weights. Wash all parts in clean gasoline or cleaning solvent. Figure 55 shows the parts of the advance mechanism.

	Fig. 53-Mechanical Breaker Advance Mechanism A-Governor Weight B-Weight Spring Pin C-Weight Spring movement, because of the manner in which they are connected with the cam, they advance the position of the cam beyond the point shown in the left-hand sketch of Fig. 53. and therefore advance the firing or spark of the engine. DISTRIBUTOR TESTING If trouble is suspected with the ignition distributor, first see if electric current is being delivered to the distributor by the primary wire from the switch and battery. If the distributor is functioning properly, the primary current will pass through the breaker arm and contact points direct from the coil when the contact points are closed. To determine whether there is any trouble at this point, disconnect the primary wire at the coil and, with the contact points closed and ignition switch turned on, strike the terminal end of the wire against the terminal on the coil. If there is a spark, the current is flowing properly. If no spark is obtained, make the following examinations: Examine the spring on the distributor breaker arm. See that this is not broken and that it is making a good contact with the primary terminal. Examine all primary wires. See that the insulation is good and that all wires are properly fastened at all points. Occasionally oil or grease will get into the distributor and form a connection between the case and the contact points. Wipe out thoroughly. There may be a "ground" in the distributor, due to defective insulation between the breaker plate and the distributor housing. Examine the contact points to see that they are clean, not burned or corroded, and are opening and closing properly. DISTRIBUTOR OVERHAUL Disassembly 1. Remove the lubrication cup, spring and bakelite shaft contact plug, Fig. 54.

			Fig. 55-Distributor Automatic Advance Mechanism Inspection 1. Inspect the shaft for wear, and check its fit in the bearings in the distributor body. If the shaft or bearings are worn, the shaft and distributor body should be replaced. 2. Mount the shaft in "V" blocks and check the shaft alignment with a dial gauge. The runout should not exceed .002". 3. Inspect the governor weights for wear or burrs and free fit on their pins. 4. Inspect the cam for wear or roughness. Then check its fit on the end of the shaft. It should be absolutely free, without any looseness. 5. Inspect the condition of the distributor points-dirty points should be cleaned and badly pitted points should be replaced. 6. Test the condenser for series resistance, microfarad capacity (.28 to .32) and insulation breakdown, following the instructions given by the manufacturer of the test equipment used.