Valve Guide: Testing and Inspection

DESCRIPTION
Check the valve stem-to-valve guide clearance of each valve in its respective valve guide with Valve Stem Clearance Tool TOOL-6505-E and Dial Indicator with Bracketry TOOL-4201-C or equivalent. Use a flat-end indicator point.

PROCEDURES
1. Install the tool on the valve stem until the lip is fully seated, and tighten the knurled set screw firmly.
2. Permit the valve to drop away from its seat until the tool contacts the upper surface of the valve guide.
3. Position and zero the dial indicator on the cylinder head.
4. Move the valve back and forth 90° from the dial indicator shaft.
5. Divide the measurement by two to determine the actual guide clearance.
- The intake clearance is 0.026-0.071 mm (0.001-0.0028 inch).
- The exhaust clearance is 0.038-0.083 mm (0.0015-0.0033 inch).
6. If the valve stem-to-valve guide clearance exceeds the service clearance, ream the valve guide for the next oversize valve stem.
- Valves with oversize stem diameters of 0.38 mm (0.015 inch) and 0.76 mm (0.030 inch) are available for service in diameters of 0.41 mm and 0.81 mm (0.016 inch and 0.032 inch) oversize.
- Always reface the valve seat after the valve guide has been reamed. Refer to Valve Guides, Reaming.
7. If the valve and/or valve seat has been refaced, it will be necessary to check the clearance between the rocker arm bearing surface or valve tappet surface (depending upon application) and base circle of the camshaft lobe with the valve train installed in the engine.