REMOVAL & INSTALLATION
Valve guides are replaceable, but it is necessary to first make sure the valve seats can be brought to specification. If the valve seats cannot be refaced, the head must be replaced anyway.
Worn guides should be pressed out from the combustion chamber side and new guides pressed in as far as they will go. In some cases, existing guides can be "knurled'' to restore the inside diameter to specifications. All this work must be performed by a reputable machine shop, as special skills and extremely sophisticated special equipment are required.
The valve guides are an integral part of the cylinder head and are not replaceable. When the valve stem guide clearance is excessive, the valve guide bores must be reamed oversize by a reputable automotive machine shop. Service valves with oversized stems are available in 0.003 in. (0.076mm) and 0.015 in. (0.38mm) increments. Corresponding oversized valve stem seals are also available and must be used with valves having 0.015 in. (0.38mm) oversized stems.
If the valve guides are reamed oversize, the valve seats must be reground afterward to ensure that the valve seat is concentric with the valve guide.