TM 5-3895-346-14
ENGINE OVERHAUL
CAMSHAFT AND BEARINGS
material (powered metal) which is identified with an indent in the top surface below the chamfer.
A method of identifying a camshaft with the cylinder head still installed is as follows:
1.
Put a dial indicator on the rocker arm clevis.
2.
Bar the engine over 3600 and the indicator will give a reading directly relative to the maximum
amount of lift on the high point of the camshaft exhaust lobe.
a.
The 4-53 low-lift camshafts have a 0.276-inch maximum lift.
b.
The 4-53 high-lift camshafts have a 0.327-inch maximum lift.
3.
The above can be accomplished with the cylinder head removed by placing the dial indicator
directly on the exhaust valve lobe of the camshaft. A reading of the maximum camshaft lift can be taken at the
high point of the lobe.
Lubrication
Lubrication is supplied under pressure to the camshaft and balance shaft end bearings via oil passages
branching off from the main oil gallery direct to the camshaft end bearings.
In addition, oil is forced through an oil passage in each camshaft which lubricates the camshaft intermediate
bearings. On the current camshafts, the intermediate journal oil grooves were eliminated and a chamfer added
to the intermediate journal oilholes. When replacing a former camshaft with a current camshaft, always use
new bearings.
All of the camshaft and balance shaft bearings incorporate small slots through which lubricating oil is directed
to the cam follower rollers.
Remove Camshaft or Balance Shaft
Whenever an engine is being completely reconditioned or the bearings, thrust washers, or the gears need
replacing, remove the shafts from the engine as follows:
NOTE
Refer to Shop Notes to install a cup plug in the front end of the camshaft.
1.
Drain the engine cooling system.
2.
Remove all accessories and as- semblies with their attaching parts as necessary to permit the
engine to be mounted on an overhaul stand (See Cylinder Block).
3.
Mount the engine on an overhaul stand.
IMPORTANT
Be sure the engine is securely mounted on the stand before releasing the lifting
sling.
4.
Remove the cylinder head(s). Refer to Cylinder Head.
5.
Remove the flywheel and the fly- wheel housing as outlined in Flywheel and Flywheel Housing.
6.
Remove the bolts which secure the gear nut retainer plates (if used) to the gears, then remove the
retainer plates.
7.
Wedge a clean rag between the gears as shown in Fig. 1, and remove the nuts from each end of
both shafts with a socket wrench.
8.
Remove the balance pulleys from the front end of the shafts as outlined Engine Balance.
9.
Remove the upper engine front cover
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