GM Full-Size Trucks 1970-1979 Repair Guide

Valve Springs



Valve spring removal and installation is part of the valve removal and installation procedure. Please refer to the appropriate procedure in this section.


See Figures 1, 2 and 3

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Fig. Fig. 1: Use a caliper gauge to check the valve spring free-length

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Fig. Fig. 2: Check the valve spring for squareness on a flat service; a carpenter's square can be used

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Fig. Fig. 3: The valve spring should be straight up and down when placed like this

  1. Place the valve spring on a flat, clean surface next to a square.
  3. Measure the height of the spring, and rotate it against the edge of the square to measure distortion (out-of-roundness). If spring height varies between springs by more than 1 / 16 in. or if the distortion exceeds 1 / 16 in., replace the spring.

A valve spring tester is needed to test spring test pressure, so the valve springs must usually be taken to a professional machine shop for this test. Spring pressure at the installed and compressed heights is checked, and a tolerance of plus or minus 5 lbs. (22 N) is permissible on the springs covered in this guide.