Valve Guides. If removed, install new valve guides as follows (see Figure 9-1 and Figure 9-8):
Install new valve guides (25, Figure 9-1) from the rocker arm side of the head. I the new guides have
tapered tops, use valve guide driver ST-1 265; if the new guides have flat tops, use valve guide driver
ST1315. ST-1 265 and ST-1315 will install the guide to the correct depth. If these special tools are not
available, use a standard valve guide driver having a pilot diameter of 0.495 inch (12.57 mm) and install
the guide to dimension D, Figure 9-8.
Check the valve fit in the new guide. If the valve will not enter the guide freely, use a floating head
remaining fixture, i and ream the guide to a bore diameter of 0.4972 to 0.4980 inch (12.629 to 12.649
If the valve seats have not been removed, refinish the valve seats in accordance with paragraph 9-9.
Valve Seats. H removed, install new valve seats as follows:
Select new oversize valve seats (26, Figure 9-1) from Table 9-2 that will allow tight installation with a
minimum of counterbore stock removal from the standard or resurfaced head.
Using a micrometer caliper, measure and record the thickness and outside diameter of the new seats.
Select the correct oversize cutter ST-1 310, for the oversize seats selected.
Using cutter ST-1 310, arbor 3375946, and insert tool kit ST-257, cut the counterbore to the correct
Cut the counterbore depth 0.006 to 0.010 inch (0.15 to 0.25 mm) deeper than the valve seat thickness for
exhaust counterbore and the combined thickness of the valve seat and the air deflector plate (27) for
If the head surface was machined, deepen the counterbore an additional amount equal to the amount of
metal that was removed from the head surface.
Upon reaching the proper depth, allow the cutter to dwell for several revolutions. This will ensure a
smooth. flat seating surface.
Table 9-2. Valve Seat Insert Selection
Be sure to measure insert before machining head or installing insert in head.