Assembly. - TM-10-3930-618-340087

install them on piston, using a piston ring remover and

(3) Place piston connecting rod in cylinder

installer. Take care not to spread rings more than

sleeve with lower end of connecting rod aligned with

necessary. Stagger ring gaps evenly around piston so

crankshaft. Using the wooden handle of hammer, tap

that no two are in line.

on upper end of piston to push it out of compressor and

into sleeve.

NOTE

(4) Place upper half of bearing in position on

Oil all rings and pistons before

connecting rod and install bearing cap and lower half of

installing them in cylinder sleeve.

bearing, making certain identifying marks are aligned.

i. Replacement of Connecting Rod Bushing and

(5) Install connecting rod nuts; torque to 45 50

Pin.

ft-lbs.

(1) connecting rod bushing (7, fig. 3-35) is

(6) Check connecting rod side play at bearing

worn, old bushing may be pressed out and a new

journal. Specified clearance is 0.003 inch to 0.009 inch.

bushing pressed in.

Specified inside diameter of

(7) Replace items which were removed in

connecting rod bushing is 0.8593 inch to 0.8596 inch and

order to remove pistons and connecting rods.

diameter of piston pin is 0.8591 inch to 0.8593 inch; this

provides a clearance of 0.0000 inch to 0.0005 inch

3-23. Valves and Rocker Arm Assembly

between pin and bushing. Maximum clearance or fit of

a. Description. Intake and exhaust valves (fig.

0.002 inch is allowable before replacement.

3-36) are high tensile alloy steel carefully heattreated to

(2) When there is no wear between piston

develop special properties required for valve service.

and pin, but wear exists between bushing and pin, install

Each valve stem is accurately ground to size and

a new bushing and ream to fit a standard size pin. If

hardened. Hardened intake and exhaust valve seat

there is wear on both the piston and bushing, an oversize

inserts are installed in the cylinder head. Valve guides,

pin of 0.005 inch or 0.010 inch may be used which will

made of high tensile iron, are pressed into the cylinder

require reaming of piston and connecting rod bushing to

head. Valve springs are held in place by a regular spring

fit.

retainer on the valve and tapered valve spring retainer

(3) bushing is loose in the connecting rod, it is

locks. Release type cap allows valve to rotate slightly

recommended that rod be replace as even a new

each time valve is opened and repositioned on its seat.

bushing would fit loosely.

The rocker arm assembly, consisting of two rocker arms

j. Assembly.

for each cylinder, is mounted on a common rocker arm

(1) Install one of the piston pin retainer rings

shaft supported by rocker shaft brackets attached to the

(5, fig. 3-35) in one end of the piston pin hole in piston.

cylinder head. The push rods extend down through the

(2) Immerse piston in boiling water for about 5

cylinder head, cylinder block, and into valve lifters which

minutes. Then insert upper end of connecting rod into

are held in place by the camshaft. Upper ends of push

piston and insert piston pin (6). Pin to connecting rod is

rods are concave to receive ends of valve lash

a very light push fit.

adjustment screws threaded into one end of rocker arm.

(3) Install other piston pin retainer at opposite

Other end of rocker arm actuates valves through push

end of piston pin.

rods. When push rods are forced upward by camshaft

k. Installation.

lobes, rocker arm forces valve open. Tension of valve

(1) When installing pistons and connecting

spring closes valve when push rods move downward.

rods, be sure to place them in their respective cylinders

An oil feed line from the engine oil gallery, connected to

with number on bearing cap opposite camshaft side of

the side of the cylinder head, leads to an oil feed in line

engine.

tube. Both ends of shaft are blocked, forcing oil out

(2) Place ring compressor over piston rings

holes at each rocker arm location and into a drilled

making certain that rings are wholly in their grooves

passage in each rocker arm, providing lubrication for the

before tightening compressor.

Tighten compressor

assembly. Oil spilled down over push rods and valve

gradually, pausing to move it sideways to be sure the

springs drains back to oil pan through overflow tube.

rings are free. Compress rings as much as possible.

3-44