Remove Valve Seat Insert

TM 10-3930-242-34

T-handle to expand collet cone until the insert is

leak (or blow-by). If any of these conditions

held securely by the tool,

e x i s t , a new valve should be installed or the

( 4 ) Insert the drive bar of the tool through

valve refaced, Valve heads should be square

t h e valve guide.

w i t h the valve stem and should not be warped.

(5) Tap the drive bar once or twice to move

If the valve heads are not square or warped,

the insert about 1/16-inch away from its seat in

n e w valves must be installed.

f. Inspect Valve Guide. After the valves have

t h e cylinder head.

(6) Loosen the collet cone and move the tool

b e e n removed, clean valve guides. After clean-

into the insert slightly so that the narrow flange

i n g , inspect valve guides for fractures, scoring,

a t the bottom of the collet is below the valve

or excessive wear, and replace if necessary. The

s e a t insert.

i n s i d e diameter of a new guide is 0.2505- to

( 7 ) Tighten the collet cone and continue to

0.2515-inch. Therefore, with new parts, the

d r i v e the insert out of the cylinder head.

valve stem to guide clearance is 0.002- to

k. Install Valve Seat Insert.

0.004-inch. If this clearance exceeds 0.005 inch,

(1) Wash the counterbores in the cylinder

i n s t a l l a new valve guide and/or valve.

h e a d for the valve seat inserts with P-D-680

g. Remove Value Guide. If the clearance bet-

s o l v e n t . Also, wash the valve inserts with the

ween the guide and valve stem exceeds the

s a m e solvent. Dry the counterbores and inserts

a b o v e limits or if the valve guide is defective,

w i t h compressed air.

the guide should be removed as follows:

( 2 ) Inspect the counterbores for cleanliness,

( 1 ) Support the cylinder head (bottom side

c o n c e n t r i c i t y , flatness, and cracks. The coun-

u p ) on wood blocks 3 inches above the work-

terbores for the valve inserts have a diameter of

bench.

1.159- to 1.160-inches and a depth of 0.298- to

(2) Drive valve guide out of cylinder head.

0.302-inch.

h. Install Valve Guide. Rest the bottom of the

( 3 ) Immerse the cylinder head for at least

cylinder head on a workbench, and proceed with

30 minutes in water heated to 180- to 200-F.

i n s t a l l a t i o n as follows:

(1) Insert the threaded end of the valve

( 4 ) Rest the cylinder head, bottom side up,

g u i d e into the installing tool.

o n bench and lay an insert in counterbore-valve

( 2 ) Locate the valve guide squarely in the

s e a t up. This must be done quickly while the

c y l i n d e r head and tap gently to start it into

c y l i n d e r head is still hot and the insert is cold

place.

(room temperature). If the temperature of the

(3) With the guide properly started, drive it

two parts is allowed to become nearly the same,

i n until its upper end is 0.010- to 0.030-inch

i n s t a l l a t i o n may become difficult and damage to

b e l o w top of cylinder head. This dimension is

t h e parts may result.

a u t o m a t i c a l l y provided by the valve guide in-

(5) Drive the insert down tight into the

staller tool. Service valve guides are "pre-

counterbore.

f i n i s h e d , " therefore, do not require reaming.

( 6 ) Grind the valve insert and check it for

i. Inspect Valve Seat Insert. I n s p e c t v a l v e

c o n c e n t r i c i t y in relation to the valve guide.

s e a t inserts for excessive wear, pitting, crack-

l. Recondition Exhaust Valve and Valve Seat,

ing, or improper seat angle. The proper angle for

CAUTION

t h e seating face of both valve and insert is 30

For the best results, do not permit grind-

degrees. When a valve insert has been ground to

ing wheel to contact the cylinder head

s u c h an extent that further grinding will cause

w h e n grinding the inserts. Valve head

g r i n d i n g wheel to contact cylinder head, a new

r e l a t i o n to cylinder head surface should

i n s e r t should be installed.

be within specified limits. After several

j. Remove Valve Seat Insert. The valve seat

grindings of the insert, the seat diameter

i n s e r t s are pressed into the cylinder head and,

becomes enlarged; thus, the valve will

t h e r e f o r e , must be removed as outlined in the

seat farther down into the cylinder head.

f o l l o w i n g procedure to avoid damage to the cy-

Exhaust valves which are to be reused may be

l i n d e r head:

refaced, if necessary. To provide sufficient valve

(1) Place cylinder head on its side on work-

strength and spring tension the edge of the

bench.

valve head should never be less than 1/32 inch.

(2) Place collet of tool inside valve insert so

B e f o r e either a new or used valve is installed,

that bottom of collet is flush with bottom of in-

the seat in the cylinder head for the valve

sert.

should be examined for proper valve seating.

(3) Hold the collet handle and turn the

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