Valve Guide: Service and Repair

VALVE GUIDE DATA
^ Replacement guides are available in two sizes and have identification grooves machined in the shank. Outside diameters are as follows:

First oversize (2 grooves)
12.88 to 12.85 mm
(0.507 to 0.506 in)

Second oversize (3 grooves)
13.00 to 12.98 mm
(0.512 to 0.511in)

^ When new guides are to be fitted they should always be one size larger than the old guide. Cylinder head bores will require reaming as follows:
- Remove the old valve guide and ream the cylinder head to the following dimensions:

First oversize (2 grooves)
12.83 mm +0.012 mm, -0.005 mm
(0.505in +0.0005 in, -0.0002 in)

Second oversize (3 grooves)
12.95 mm +0.012 mm, -0.005 mm
(0.510in +0.0005 in, -0.0002in)

- Immerse the cylinder head in boiling water for 30 minutes.
- Coat the guide with graphite grease, and, using 18G 1432, drift in the guide from the camshaft side until the circlip is seated in the groove.

NOTE: To fit the guide correctly, the interference should not be sufficient to cause the use of excessive force.

NOTE: After fitting a valve guide, the valve seat must be recut.