0.001 inch (0.03 mm) or if chipped,
flaked, or scored. See tabulated data in
Chapter 1 for shell thickness.
(b) Total worn maximum oil clearance
should not vary more than 0.001 inch
(0.05 mm) between adjacent main
bearings. Refer to tabulated data in
Under no circumstances should an
attempt be made to scrape bearing
shells, nor should they be lapped or filed
to increase oil clearances. A properly
fitted bearing will appear dull gray after a
reasonable period of service, indicating
it is running on an oil film. Bright spots
indicate metal-to-metal contact and black
spots indicate excessive clearance.
(3) Connecting rods.
(a) Magnaflux all connecting rods, caps and
bolts; discard if cracks are detected.
Be sure rod and cap are mated at all
(b) Check rods for cracks with 1800-ampere
current AC equipment or 1500-ampere
current DC or rectified AC equipment
longitudinally between plates.
(c) Check rods for cracks with 3000 to 3400
ampere-turns with AC equipment or
2600 to 2800 ampere-turns with DC or
rectified AC equipment in a coil.
Ampere-turns is defined as the amperage
flowing through the coil, multiplied by
the number of turns in the coil. Most
coils contain four turns and therefore
only 700 amperes need to be applied
with DC equipment, or, 850 amperes with
(d) Apply 1.5 percent wet solution while
current is on. Make visual inspection
after each application of current.
(e) Assemble cap to rod and alternately
tighten nuts to operating tension by
torque method as specified in Chapter
(f) Check crank pin bore with a dial bore
gauge or inside micrometers. Correct
size is important to provide correct
bearing crush. New dimension after rod
separations are 4.0018 to 4.0028 inch
(101.646 to 101.671 mm).
(g) Check piston pin bushing diameter with
plug gauge or with inside micrometers.
Refer to tabulated data in Chapter 1.
(h) Use rod checking fixture and locating
mandrel to check rod alignment.
Difference in reading should not exceed
0.015 inch (0.38 mm).
(i) Check connecting rod bolts, bolt holes,
and bolt pads. The bolt head must rest
squarely on milled surfaces of the rod.
(j) If connecting rod bolts have been
tightened excessively, they may be
permanently stretched, in which case
they must be discarded. Discard bolt if
smallest diameter is less than 0.540
inch (13.72 mm).
(k) Check bolt pilot OD; discard bolt if pilot
is smaller than 0.6242 inch (15.855
(l) Discard all bolts and