Figure 3-41. Minimum distance between top and bottom faces of cylinder head.

TM 10-3930-242-34

tubes. If inspection revealed cracks in the cylin-

cylinder head, the amount of stock removed

s h o u l d be stamped on the face of the fire deck

der head, it should be replaced.

(c) Inspect cam follower bores in cylinder

n e a r the outer edge of the head, in an area not

head for scoring or wear. Light score marks may

used as a sealing surface. Not over 0.020 inch of

be cleaned up with crocus cloth wet with fuel oil.

m e t a l should be removed from the fire deck of

I f bores are excessively scored or worn so that

a n y cylinder head. The distance from the top

c a m follower-to-head clearance exceeds 0.006

d e c k to the bottom (fire deck) of the cylinder

i n c h , replace the cylinder head.

head must not be less than 4.376 inch as shown

i n figure 3-41. After a cylinder head has been

(d) Check valve seat inserts for cracks or

r e f a c e d , and new injector tubes have been in-

burning. Also check valve guides for scoring.

s t a l l e d , the cylinder head should be pressure

(e) Check water nozzles for tightness in

c h e c k e d . The top surface of the cylinder block

f o u r valve cylinder heads. Water nozzles are

w i l l not warp to the extent that machining will

used only in the passages between cylinders. To

b e c o m e necessary, therefore, no warpage limits

i n s t a l l or replace cylinder head water nozzles:

o r machining limits are required.

1. Be sure water inlet ports in bottom of

(b) The cylinder head may be checked for

h e a d are clean and free of scale. Water holes

may be cleaned up with a 5/6-inch diameter drill.

l e a k s using the following procedure:

1. Seal off the waterholes in the head,

B r e a k the edges of holes slightly.

2. Check for press fit of nozzles in cylin-

u s i n g steel plates and suitable rubber gaskets

d e r head. If water holes in head have been en-

held in place by bolts.

2. Install dummy or scrap injectors to

l a r g e d by corrosion, use wooden plug or other

suitable tool to expand nozzle, so that they will

i n s u r e seating of the injector hole tubes. The

r e m a i n tight after installation.

dummy injectors may be made up with old injec-

3. Press the nozzles into place with out-

tor nuts and bodies, the injector spray tip is not

l e t holes positioned toward longitudinal center-

n e c e s s a r y . Tighten the injector clamp bolt to

l i n e of cylinder head. The angle between the

2 5 - 3 0 foot-pounds torque.

3. A p p l y 8 0 - 1 0 0 p s i a i r p r e s s u r e t o

outlet holes in the nozzle is 90. Nozzles should

be from flush to 1/32inch below bottom surface of

w a t e r jacket by drilling and tapping into one of

cylinder head, otherwise interference with

t h e waterhole cover plates for an air hose con-

proper seating of the head on the cylinder block

n e c t i o n . Then immerse the head in a tank of

may be encountered.

water previously heated to 180-200 F. for 20 mi-

n u t e s to thoroughly heat the cylinder head. Ob-

CAUTION

s e r v e the water in the tank for bubbles indicat-

ing cracks or leaks.

When installing plugs in fuel manifolds,

4. F o l l o w i n g t h e p r e s s u r e t e s t , d r y t h e

apply a small amount of sealant that is

h e a d with compressed air.

merchandised as a "dual purpose sealer"

5. R e p l a c e a n y l e a k i n g i n j e c t o r h o l e

to threads of plugs only. Work sealant

Figure 3-41. Minimum distance between top and bottom

faces of cylinder head.

3-47