Operating instructions

6-6 FEBRUARY 1989
c. Replacement bushings are available in standard,
.0015", .003" and .005" oversize on the outside
diameter.
d. A special tool for removing and replacing these
bushings has been developed by Borroughs Tool and
Equipment Corporation, 2429 North Burdick Street,
Kalamazoo, Michigan. We recommend that this tool
only be used for these operations.
e. Counterweight pins are identified by dash numbers
stamped on one end. Because the damper order is
controlled by this pin diameter, it is imperative that
only the correct pin, properly identified, be used.
6-19. CAMSHAFT. Inspect the journal for scoring,
corrosion and overheating. Inspect lobes for pitting at
the toes and for evidence of overheating or unusual
wear.
NOTE...The following rework procedure is
for camshaft P/N 629726. See service bulletin
M86-14 or current revision as applicable.
Camshafts manufactured to Change letter A
thrn Z and AA are not qualified for the repair
procedure outline below and should not be
reworked or reused. Only camshafts with
Change Letter AB and after are qualified for
the repair procedure outlined below.
1. Dress the outer edges of the cross holes,
approximately .010-.020, with the use of a Dremel
tool and emery wheel point No. 953 (or equivalent)
paying particular attention to the edge of the cross
hole where it intersects the fillet of the groove
2. Shot peen the entire groove including its radii
using SAE 330 shot to an intensity of .013 to .015
inches with an A2 strip.
3. Comply with all other procedures and inspection
requirements set forth in this overhaul manual
including, but not limited to, the procedures and
inspection requirements relating to magnetic particle
inspection and dimensional and visual inspection.
4. Identify reworked cams: vibro etch M86-14 after
the part number to show compliance with
service bulletin M86-14 or current revision as
applicable.
WARNING ...The benefits of this repair
procedure may be negated if the camshaft
bearing surface or its supports in the
crankcase are worn so as to exceed
running clearance of .001 to .005 specified
in the table of limits section of this manual.
6-20. CONNECTING RODS. Use a telescoping
gauge and an outside micrometer caliper to measure
all worn bushings and locally replaced bushings. If a
bushing was replaced locally, it is also necessary to
check its alignment with the big end bearing seat. The
simplest method of making alignment measurements
requires a push fit arbor, preferably at least eight
inches long, for the bushing bore and another for the
bearing seat, a surface plate, two matched vee blocks
and two blocks of ground flat steel stock of equal
height. To measure twist, insert the arbors into the rod
bores; then lay the big end arbor in the vee blocks on
the surface plate, and place the ground steel blocks
under the ends of the bushing arbor at a measured
distance apart. A feeler gauge may be used to detect
any clearance at either end under the bushing arbor.
This, divided by the separation of the blocks in inches,
will give the twist per inch of length. (Refer to limit
in Section VI.) To measure bushing and bearing
convergence, mount a dial indicator on a surface
gauge, and swing the rod around the big end arbor to
the vertical position against a firm stop. Pass the
indicator over the bushing arbor at points an exact
number of inches apart. The difference in readings at
the two ends, divided by the distance between points
of measurements, again gives the misalignment per
inch, as specified in Section VI.
6-21. GEARS. Inspect gear teeth for signs of over-
heating and excessive wear. Normal wear produces a
fine polish on the tooth thrust faces. Alteration of the
tooth profiles, score marks and pitting are sufficient
cause for rejection.
6-22. PISTONS AND RINGS. Inspect the skirt for
long, deep scores which indicate overheating and are
sufficient cause for rejection. If a telescoping gauge is
used to measure the pin bore, do not allow the spring
pin to expand rapidly so as to strike the wall hard.
Inspect visually for thorough cleaning, including the
oil relief holes in the third ring groove. It is not
necessary to remove light scores or discoloration from
the exterior surfaces, and it is not advisable to use
abrasive (including crocus cloth) on the skirt, since the