TM 5-3825-226-24
CAMSHAFT
CAMSHAFT
When reconditioning an engine, check the diameter
of the camshaft bearing journals and the camshaft lobe
height.
Camshaft bearing journals have a diameter of
2.5000 ± .0005 in. (63.500 ± 0.013 mm) and the
minimum diameter worn is 2.4970 in. (63.424 mm).
To find lobe lift (A) of camshaft, use the following
procedure:
1.
Measure lobe height (B) of one exhaust and one
intake lobe.
2.
Measure base circle (C) of one exhaust and one
intake lobe.
3.
Subtract base circle (C) dimension (STEP 2)
from lobe height (B) dimension (STEP 1). The
difference is actual lobe lift (A).
4.
The specified (new) lobe lift (A) is:
(a)
Exhaust lobe ........ .3071 in. (7.800 mm)
(b)
Intake lobe ...........3077 in. (7.816 mm)
5.
The maximum permissible difference between
actual lobe lift (STEP 3) and specified lobe lift
(STEP 4) is .025 in. (0.64 mm).
CAMSHAFT LOBE
A. Lobe lift. B. Lobe height. C. Base circle.
With camshaft' installed in the cylinder block, check end
play. End play with new components should be .007 ±
.003 in. (0.18 ± 0.08 mm). The maximum permissible
end play is .020 in. (0.51 mm).
CAMSHAFT FOLLOWERS
Use an 8S2293 Magnet to remove the cam followers.
REMOVING CAM FOLLOWERS
Cam followers establish a wear pattern with the
camshaft lobes. Identify and reinstall the followers
removed. Dishing or circular wear pattern is allowed on
the cam follower face, providing the wear face keeps a
polished appearance. Replace the follower if the wear
face is rough or shows signs of scuffing. A new follower
can be used with an old camshaft, providing the lobe is
in good condition. Put engine oil on the cam followers
and the camshaft lobes before installing the cam
followers.
NOTE: Use new cam followers with a new camshaft.
CAMSHAFT GEARS
1.
Remove screw (1) and washer (2) from end of
camshaft.
REMOVING TIMING ADVANCE RETAINING SCREW
1. Screw. 2. Washer.
2.
Remove timing advance unit from the camshaft.
3.
Install puller (A), with spacer (C) over the shaft
in the camshaft spacer (B) on spacer (C) as
shown and remove the gear from the camshaft.
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