GM Full-Size Trucks 1970-1979 Repair Guide

Distributor

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REMOVAL & INSTALLATION



1970-74 Vehicles

See Figures 1 and 2



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Fig. Fig. 1: Exploded view of a 6-cylinder engine point-type distributor



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Fig. Fig. 2: Exploded view of an 8-cylinder engine point-type distributor

  1. Remove the distributor cap and position it out of the way.
  2.  
  3. Disconnect the primary coil wire and the vacuum advance line.
  4.  
  5. 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.
  6.  
  7. Remove the holddown bolt and clamp and remove the distributor.
  8.  

To install:
Engine Not Disturbed:
  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, and the vacuum hose.
  6.  
  7. Start the engine and check the ignition timing.
  8.  

Engine Disturbed:
  1. Turn the engine so the No. 1 piston is at the top of its compression stroke. This may be determined by covering the No. 1 spark plug hole with your thumb and slowly turning the engine over. When the timing mark on the crankshaft pulley aligns with the 0 on the timing scale and your thumb is pushed out by compression, No. 1 piston is at top dead center (TDC).
  2.  
  3. Install the distributor to the engine block so that the vacuum advance unit points in the correct direction.
  4.  
  5. Turn the rotor so that it will point to the No. 1 terminal in the cap.
  6.  
  7. 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.
  8.  
  9. Tap the starter a few times to ensure that the oil pump shaft is mated to the distributor shaft.
  10.  
  11. 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.
  12.  
  13. After correct positioning is assured, turn the distributor housing so that the points are just opening. Tighten the retaining clamp.
  14.  
  15. Install the cap and primary wire. Check the ignition timing. Install the vacuum hose.
  16.  

 
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