Thoroughly clean out each valve guide and then insert the appropriate valve. Using a dial gauge, test the movement of the valve at 90 degrees to the center line of the
Cylinder Head, ensuring that the valve is held from its seat by about 1/16 inch. The total valve stem movement indicated by the gauge needle must be divided by two to obtain the actual stem clearance. If the stem clearance exceeds the specified limits, it will be necessary to ream the valve guide and fit oversize valve stems, checking availability with a Chevrolet dealer or engine repair specialist for this servicing operation. Each valve spring and damper should be compared with the specified free-length and renewed if shorter; it is recommended to install new springs and dampers if the engine has covered more than 30,000 miles since they were new.