Cylinder Head: Valve Guide Servicing

NOTE: When reconditioning valves, ensure interference angles of valve and seat are not lapped out. Remove all grooves and/or score marks from end of valve stem with an oil stone. DO NOT remove more than .010" (.254 mm) from end of valve stem.

Valve guides are integral with cylinder head. Check valve stem-to-guide clearance. If clearance exceeds service limits, recondition valve guide. To check valve guide wear, insert Valve Stem Clearance Tool (6505-E) onto valve stem until fully seated and tighten set screw. Permit valve to drop away from seat until tool contacts valve guide.
Attach dial gauge to cylinder head. Position gauge indicator against center portion of tool's spherical section at right angle. Move valve in guide and note guide wear shown on dial gauge. Divide reading by 2 (division factor for tool). Resulting measurement is valve stem clearance. See VALVE SPECIFICATIONS TABLE .
Use valve guide cleaning tool for cleaning guides. To ream guides for installation of valves with oversize stems, use reamers in sequence and reface valve seat after valve guide is reamed.
Valve guide reamers are furnished in: .003" (.076 mm) oversize with standard diameter pilot, .015" (.380 mm) oversize reamer with .003" (.076 mm) oversize pilot, and .030" (.760 mm) oversize reamer with .015" (.380 mm) oversize pilot.
If valve face is reground, check margin width dimension. Check valve seats for proper angle and seat width. Measure valve seat runout. Valve seat runout should be within .002" (.05 mm) for intake and exhaust. Valve seat must be refaced after guide has been reamed.
Intake and exhaust valve seat width is .060-.080" (1.52-2.03 mm). Use scraper to break (lightly chamfer or bevel) sharp top inside edge of guide. After valve guide repair, inspect valve stem end for wear before installation. Valve stem end may be reconditioned by grinding.