Toyota Pick-ups/Land Cruiser/4Runner 1970-1988

Octane Selector

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See Figure 1

The octane selector is used as a fine adjustment to match the ignition timing to the grade of gasoline being used. It is located near the distributor vacuum advance unit, under a plastic cover. Normally the octane selector should not require adjustment, however, adjustment is as follows:

  1. Align the setting line with the threaded end of the housing and then align the center line with the setting mark on the housing.
  2.  
  3. Drive the truck at 16-22 mph in High gear on a level road.
  4.  



Click image to see an enlarged view

Fig. Fig. 1: Octane selector setting

  1. Depress the accelerator pedal all the way to the floor. A slight pinging sound should be heard. As the vehicle accelerates, the sound should go away.
  2.  
  3. If the pinging sound is loud, or if it fails to disappear as the vehicle accelerates, retard the timing by turning the knob toward R (retard).
  4.  
  5. If there is no pinging sound at all, advance the timing by turning the knob toward A (advance).
  6.  

On 1973-79 models, do not turn the octane selector more than1/2turn toward R. Do not turn it toward A at all.

  1. When the adjustment is completed, replace the dust cover.
  2.  

One graduation of the octane selector is equal to about 10 degrees of crankshaft angle.

 
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