Figure 6-13. Removing valves.

(6) If it has been determined that valve guide

replacement is required, this operation should be done

at this time. Old guides may be removed with a suitable

puller or by reaming to a thin shell and collapsing them.

New guides are pressed in place on an arbor press with

the aid of a mandrel. Service guides are especially

machined to provide proper stem clearance without

further reaming after installation. In production, the

valve guide shoulders are intentionally held above the

cylinder head upper service to avoid valve binding

caused by cocking the guide if one side of the shoulder

contacts unevenly. Do not try to bottom these guides.

Install service guides in the same way. Use .010 inch

feeler stock as a spacer under the shoulder when

installing, (fig. 6-14).

(7) Check the exhaust valve seat inserts for

cracks or loose mounting. Refer to figure 6-15 and

remove any defective valve seats. Replace seats with

new 1/32 oversized valve seats. Counterbore the valve

seats to a diameter of 1.655 to 1.656 inches. This will

Figure 6-13. Removing valves.

provide a 0.003 to 0.005 inch press fit. Counterbore

deeply enough so that the boring tool will clean up the

bottom of the bore to assure proper heat conduction

(4) Do not remove the valve guides or seats

from the valve insert. Chill the valve seat in dry ice for

unless inspection indicates that they are faulty.

20 minutes. Install the valve seat in place with a piloted

driver using an arbor press or by applying light blows

c. Cleaning, Inspection, and Repair.

with a hammer until the valve seat is resting against the

bottom of the bore.

(1) Clean the valves, valve springs, retainers,

and valve stem caps with an approved cleaning solvent;

(8) Check the valve springs for cracks and

dry thoroughly. Remove carbon deposits with a wire

distortion. Test compression strength with a spring

brush.

tester. Compression strength must be as follows:

(2) Clean the valve guides installed in the

Valve closed-Spring length 1 15/16" Comp. Press 49

cylinder head with a valve guide cleaner or a wire brush.

lbs. 4 lbs.

Remove all lacquer and other deposits.

Valve open-Spring length 1 19/32" Comp. Press 86 lbs.

6 lbs.

(3) Clean valve seats with a wire brush.

(4) Inspect the valves for cracks, bent stems,

(9) Grind the valve seats. The seat angle is

distortion, and wear. If the valves are not seriously

45 degrees. Use a dial indicator figure 6-16 to check

damaged, regrind them. After grinding, the valve head

the valve seat for runout. The total indicator reading

thickness must be at least 50 percent of the thickness of

must not exceed 0.002 inch. Clean the valve seat and

a new valve. Replace the valves if they are ground to

surrounding area thoroughly after grinding.

less than this amount. Check the reground valves on V

blocks with an indicator. The contact face must be true

(10) After the valves and seats have been

with the stem to within 0.002 inch. Repeat the refining

refaced and reground coat the seat lightly with Prussion

operation if necessary.

blue and drop the valve into place, oscillating it slightly

to transfer the blue pattern

(5) Check for loose or worn valve guides.

Check the internal diameter of the valve guide with a

telescope gage and a micrometer. Replace guides that

are worn to a bellmouthed shape.

6-13