• Advance Rate
• Initial Timing
• RPM/Advance Start Point
  
  
  
  
  PN 8981
  

Programmable Timing Computer,
PN 8981
The MSD Programmable Timing Computer has several features in common with the pre-programmed PN 8980 Timing Computer. Both are adjustable for 4, 6 and 8-cylinder operation and both models have a High Speed Retard function.
The difference between the two models is that the PN 8981 Programmable Timing Computer has an adjustable timing curve whereas the PN 8980 is fixed. The Programmable Computer allows you to adjust the start point, rate and total amount of the advance curve to fit your application.
First, the idle or initial timing must be set with the Initial Timing potentiometer. This can be adjusted up to 20° from full advance (total timing). Second, the rpm level where the timing will begin advancing needs to be set. This can be set from 1,000 to 3,000 rpm. The last adjustment is the slope or how fast you want the timing to advance. The range of adjustment for this feature is from 1/2° per 1,000 rpm to 20° per 1,000 rpm. All of these timing adjustments are made with locking potentiometers located on the side of the unit.

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The PN 8981 must be used with an MSD Ignition Control and is supplied with a 2°, 3° and 4° module. Page 90 lists a full selection of retard modules and selectors.

Programmable Timing Computer
PN 8981*

*Not legal for sale or use on pollution controlled vehicles.