Valve Guide: Service and Repair

CAUTION:
Reface The Valve Seat
Always check the valve seat for runout and contact area AFTER the valve guide has been replaced or repaired. If necessary, reface the valve seat.

Lapping the Valve Seat
The interference angle of the valve and seat should NOT be lapped out.

Inspect The Valve
Remove all grooves or score marks from the end of the valve stem and chamfer it as necessary. Follow proper procedure.

If the valve and/or valve seat has been refaced,
check the clearance between the rocker arm pad and the valve stem with the valve train assembly installed in the engine.

NOTE:
Tool Kit
If it becomes necessary to ream a valve guide to install a valve with an oversize stem, a reaming kit is available which contains the following reamer and pilot combinations: 0.38 mm (0.015 inch) "OS" reamer with 0.076 mm (0.003 inch) "OS" pilot, and a 0.76 mm (0.030 inch) reamer with a 0.38 mm (0.015 inch) "OS" pilot.

Reamer Useage
When replacing a standard size valve with an oversize valve, always use the reamer in sequence (smallest oversize first then next smallest, and so forth) so the reamers will not be overloaded.

If oversize valve stems and oversize stem seals are not available,
Bore out original guide and install service bushing. Ream ID for specified clearance for standard-size valve. Reface valve seat, as required. Install standard-size valve stem seal.

Finishing
Use a suitable scraper to break the sharp corner (inside diameter) at the top of the valve guide. Failure to do so may result in possible valve train wear and/or damage.