e. Valve Seat Inserts.
mended press fit cannot be obtained when installing new
(1) Removal. Inspect the valve seat inserts.
standard size valve seat inserts, the bores must be
If they are loose, cracked or pitted, new
machined .005 inch larger than their original I.D. and
inserts must be installed. The valve seat
.005 inch oversize valve seat inserts must be installed.
inserts are a press fit in the cylinder head.
Refer to table 2.1 for O.D. of valve seat inserts and
Remove valve seat inserts by electric
corresponding I.D. of bores in cylinder head. The
welding three small beads on inside
dimensions shown in table 2.1 provide an interference fit
circumference of the insert as shown in
of .002 inch to .004 inch for intake valve seat inserts
figure 59. Allow insert to cool, then lift out
and .002 inch to .0035 inch for exhaust valve seat
or pry out with a bar.
Table 2.1. Valve Insert Dimensions
Do not weld in encircled area (fig.
O.D. of New
Insert Bore in
59). Protect machined surfaces from
Size-Intake 1.6445 inch-
(a) It is imperative that the original
press fit be maintained between
new inserts and insert bores in the
cylinder head. If insert bores in
cylinder head are damaged or worn
enough so that the recom-
counterbores in cylinder head are
clean, free of burrs, and of the
correct size to assure the specified
(c) Chill inserts for 2 to 4 minutes in a
dry ice container or cold box.
(d) Place cylinder head bottom side up
on a bench.
counterbores for the inserts with
compressed air and start an insert
into the counterbore (valve seat
side up). Inserts must be started in
place "true" with the counterbore in
the cylinder heads.
(e) Using a valve seat insert installing
tool, drive insert down tightly into
counterbore. This operation must
be done quickly while insert is cold.
Figure 59. Beads welded on valve seat inserts.