GM Chevy Mid-Size Cars 1964-1988 Repair Guide

Distributor

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For ignition system service not found below, please refer to Engine Electrical of this information.

REMOVAL & INSTALLATION



See Figures 1 and 2

Point-Type Ignition, 1964-74
  1. Disconnect the negative battery cable.
  2.  
  3. Remove the distributor cap and position it out of the way.
  4.  
  5. Disconnect the primary coil wire and the vacuum advance hose.
  6.  
  7. Scribe a mark on the distributor body and the engine block showing their relationship. Mark the distributor housing to show the direction in which the rotor is pointing. Note the positioning of the vacuum advance unit.
  8.  
  9. Remove the hold-down bolt and clamp and remove the distributor.
  10.  
  11. To install the distributor with the engine undisturbed:
    1. Reinsert the distributor into its opening, aligning the previously made marks on the housing and the engine block.
    2.  
    3. The rotor may have to be turned either way a slight amount to align the rotor-to-housing marks.
    4.  
    5. Install the retaining clamp and bolt. Install the distributor cap, primary wire or electrical connector, and the vacuum hose.
    6.  
    7. Start the engine and check the ignition timing.
    8.  

  12.  
  13. To install the distributor with the engine disturbed:
    1. Turn the engine to bring the No. 1 piston to the top of its compression stroke. This may be determined by inserting a rag into the No. 1 spark plug hole and slowly turning the engine over. When the timing mark on the crankshaft pulley aligns with the 0 on the timing scale and the rag is blown out by compression, the No. 1 piston is at top dead center (TDC).
    2.  

  14.  

On Mark IV (big block) V8 engines there is a punch mark on the distributor drive gear which indicates the rotor position. Thus, the distributor may be installed with the cap in place. Align the punch mark 2 degrees clockwise from the No. 1 cap terminal, then rotate the distributor body1/8turn counterclockwise and push the distributor down into the block.

  1. Install the distributor to the engine block so that the vacuum advance unit points in the correct direction.
  2.  
  3. Turn the rotor so that it will point to the No. 1 terminal in the cap.
  4.  
  5. Install the distributor into the engine block. It may be necessary to turn the rotor a little in either direction in order to engage the gears.
  6.  
  7. Connect the negative battery cable, then tap the starter a few times to ensure that the oil pump shaft is mated to the distributor shaft.
  8.  
  9. Bring the engine to No. 1 TDC again and check to see that the rotor is indeed pointing toward the No. 1 terminal of the cap.
  10.  
  11. After correct positioning is assured, turn the distributor housing so that the points are just opening. Tighten the retaining clamp.
  12.  
  13. Install the cap and primary wire. Check the ignition timing. Install the vacuum hose.
  14.  



Click image to see an enlarged view

Fig. Fig. 1: Scribe matchmarks for the distributor housing and rotor alignment



Click image to see an enlarged view

Fig. Fig. 2: Lift upward until the shaft clears the bore in the intake manifold, then tilt and remove the distributor

HEI Distributor, 1975 and later

  1. Disconnect the negative cable from the battery.
  2.  
  3. Tag and disengage the feed and module terminal connectors from the distributor cap.
  4.  
  5. Disconnect the hose from the distributor vacuum advance unit (1975-80 only).
  6.  
  7. Depress and release the 4 distributor cap-to-housing retainers and lift off the cap assembly.
  8.  
  9. Scribe a mark on the distributor body and the engine block showing their relationship. Mark the distributor housing to show the direction in which the rotor is pointing or otherwise matchmark the rotor with the housing.
  10.  
  11. Loosen and remove the distributor hold-down bolt and clamp, then carefully lift the distributor out of the engine. Note the position of the rotor alignment mark on the housing and make a second mark on the housing to align with the rotor. You may wish to reinstall the distributor cap in order to protect the internal components from damage.
  12.  

UNDISTURBED ENGINE
  1. With a new O-ring on the distributor housing and the rotor aligned with the second mark on the housing, install the distributor, taking care to align the distributor body mark with the mark scribed on the engine. When fully installed, the rotor should turn and align with the first distributor housing mark and therefore point in the same direction as before removal. It may be necessary to lift the distributor and turn the rotor slightly to properly align the gears and the oil pump driveshaft.
  2.  
  3. With the respective marks aligned, install the clamp and bolt finger-tight.
  4.  
  5. Install and secure the distributor cap.
  6.  
  7. Engage the feed and module connectors to the distributor cap.
  8.  
  9. Connect a timing light to the engine and either plug the vacuum hose or disconnect the distributor set timing connector, as applicable.
  10.  
  11. Connect the negative cable to the battery.
  12.  
  13. Start the engine and set the timing, then secure the distributor clamp bolt.
  14.  
  15. Recheck the timing to assure it was not changed while tightening the clamp bolt, then shut the engine OFF . Disconnect the timing light and either unplug and connect the hose to the vacuum advance or reconnect the distributor timing connector.
  16.  

DISTURBED ENGINE
  1. Remove the No. 1 spark plug.
  2.  
  3. Place a finger over the No. 1 spark plug hole and rotate the engine by hand until the compression can be felt.
  4.  

An alternate method of finding No. 1 TDC when the valve cover for that cylinder bank is removed involves watching to see if the valves open as the timing mark approaches 0. If any valves open, then the engine is 360 degrees out of No. 1 TDC and should be turned one full revolution. If the valves remain closed, it signifies that the cylinder was on its compression stroke and is at TDC when the mark reaches 0 on the timing plate.

  1. Align the timing mark on the crankshaft pulley with the 0 mark on the timing plate.
  2.  
  3. Align the distributor rotor near the No. 1 spark plug tower.
  4.  
  5. Install the distributor, the hold down clamp, the bolt and the cap. It may be necessary to turn the rotor a little in either direction in order to engage the gears.
  6.  

With the distributor installed, make sure that the rotor is aligned with the No. 1 spark plug tower of the cap.

  1. Start and run the engine, then check and adjust the ignition timing.
  2.  

 
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