Section XII ENGINE

Section XIIL ENGINE

3-77. General

3-78. Valve Tappet Adjustment

a. The internal combustion, gasoline engine is of

a. Refer to paragraphs 3-81b(1) through 3-81b(5) and

overhead valve, wet sleeve construction. The engine is

remove parts as described.

mounted on the pumping unit skids and housed by top,

side, and end panels. A port is provided in the top panel

b. Refer to figure 3-55 and remove valve cover.

for the exhaust pipe.

c. Refer to figure 3-56 and adjust valve clearance as

b. The combustible mixture of gasoline and air flows

follows:

from the carburetor, through the intake manifold, into

(1) Rotate crankshaft to top dead center of number

the combustion chamber. Flow of the mixture into the

1 cylinder; check both rocker arms for freedom.

combustion chamber is controlled by the intake valves.

The intake valves are operated by adjustable tappets

(2) Refer to figure 3-56 and adjust the valve tappets

which ride the lobes of the cam.

on cylinder number 1.

c. After the combustible mixture has been burned in

(3) Turn crankshaft until intake valve just starts to

the cylinder, the exhaust valves open and the exhaust

open on cylinder number 3; adjust valve tappets on

gases are forced into the exhaust manifold. Operation

cylinder number 5 as described above. Turn crankshaft

of the exhaust valves is controlled by tappets which ride

until intake valve just starts to open on cylinder number

the lobes of the cam.

6; adjust valve tappets on cylinder number 3. Turn

crankshaft until intake valve just starts to open on

d. Exhaust gases are carried from the exhaust

cylinder number 2; adjust valve tappets on cylinder

manifold to the atmosphere through the exhaust pipe

number 6. Turn crankshaft until intake valve just starts

and muffler. The muffler quiets the noise of the engine.

to open on cylinder number 4; adjust valve tappets on

cylinder number 2. Turn crankshaft until intake valve

Figure 3-55. Valve cover removal and installation.

3-46