Valve Guide

Valve guides in these engines are an integral part of the head and, therefore, cannot be removed. For service, guide holes can be reamed oversize to accommodate one of several service valves with oversize stems.
Check the valve stem clearance of each valve (after cleaning) in its respective valve guide. If the clearance exceeds the service limits of .004 inch on the intake or .005 inch on the exhaust, ream the valve guide to accommodate the next oversize diameter valve stem.
Select the reamer for the smallest oversize which will provide a clean straight bore through the valve guide. After reaming, a new seat should be cut into the head to assure perfect seating of the new valve.