Valve Guide: Service and Repair

V8-250
Check valve stem to valve guide clearance, clearance should be no more than .005 inch. Service valves are available in standard (.343 inch) and .003, .006 and .013 inch oversizes. If clearance is found to be excessive, valve guide should be reamed out to next oversize using appropriate reamer, and a corresponding oversize valve installed. On some engines, valves with a .003 inch oversize diameter and .003 inch oversize valve guides are installed at the factory. Engines so fitted will be identified by a "3" stamped on the cylinder head gasket surface inline with the oversize valve.