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Valve Seat Roundness Measurement Procedure

WARNING: This page is about a different car, the 2002 Oldsmobile Aurora and 2001 Oldsmobile Aurora. However, it is still accessible from the selected car via links, so may be relevant.
  1. Measure the valve seat roundness using a dial indicator attached to a tapered pilot installed in the guide. The pilot should have a slight bind when installed in the guide.
    CAUTION: The correct size pilot must be used. Do not use adjustable diameter pilots. Adjustable pilots may damage the valve guides.
  2. Compare your measurements with the specifications listed in Engine Mechanical Specifications .
  3. If the valve seat exceeds the roundness specification, you must grind the valve and valve seat using the Valve and Seat Reconditioning Procedure.
  4. If new valves are being used, the valve seat roundness must be within 0.05 mm (0.002 in).
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