GM Full-Size Trucks 1980-1987 Repair Guide

Spark Plug Wires

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See Figures 1 and 2

Visually inspect the spark plug cables for burns, cuts, or breaks in the insulation. Check the spark plug boots and the nipples on the distributor cap and coil. Replace any damaged wiring. If no physical damage is obvious, the wires can be checked with an ohmmeter for excessive resistance.



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Fig. Fig. 1: Most HEI equipped engines covered in this guide should be equipped with a spark plug wire retainer harness that snaps to the top of the wires on the distributor cap. As in the case of this photo, it is not uncommon to find these missing.



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Fig. Fig. 2: If the retainer harness is missing and all wires must be disconnected from the distributor cap at the same time, be sure to tag the wires to insure proper installation

When installing a new set of spark plug cables, replace the cables one at a time so there will be no mix-up. Start by replacing the longest cable first. Install the boot firmly over the spark plug. Route the wire exactly the same as the original. Insert the nipple firmly into the tower on the distributor cap. Repeat the process for each cable.

See Figures 3, 4, 5, 6, 7, 8 and 9

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Fig. Fig. 3: Gasoline Engine Tune-Up Specifications



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Fig. Fig. 4: Gasoline Engine Tune-Up Specifications



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Fig. Fig. 5: Diesel Engine Tune-Up Specifications



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Fig. Fig. 6: Troubleshooting Engine Performance



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Fig. Fig. 7: Troubleshooting Engine Performance



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Fig. Fig. 8: Troubleshooting Engine Performance(Cont.)



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Fig. Fig. 9: Troubleshooting Engine Performance(Cont.)

 
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