Crankshaft; Connecting Rods; Pistons, Pins And Rings - Ford 1961 TRUCK 100 SERIES Shop Manual

1·22
GROUP 1-
ENGINES AND EXHAUST SYSTEMS
A VS B
=
VERTICAL TAPER
C VS D
=
HORIZONTAL TAPER
A V$ C AND B VS D
=
OUT-Of-ROUND
CHECK FOR OUT-Of-ROUND AT
EACH END OF JOURNAL
I
/
"
I
\
\
\
I
I
.. "' .....
r~ I,."'"
I
I
., J J
" I
"-!..,<W'-_ _ _
~~"
"
.
. . . _-",--"
,
'-"': -'
Al01S-A
FIG.
37- Crankshafl Journal
Measuremenl
C hec k the distributor drive gear
for broken or chipped teeth.
REPAIRS
Remove light scuffs, scores, or
nicks from the camshaft machined
surfaces
with
a smooth oilstone.
CRANKSHAFT
CLEANING
Ha ndle the crankshaft with care
to avoid possible fractures or dam-
age to the fi nished surfaces. Clean the
crankshaft with so lvent, then blow
out all oil passages with compres-
sed air.
INSPECTION
Inspect main and connecting rod
journa ls for cracks, scratches,
grooves, or scores.
Measure the diameter of each jour-
nal in at least four places to deter-
mine out-of-round, taper, or under-
size condition (Fig. 37).
On an engine used with a manual
shift trans mi ss ion, check the fit of
the clutch pilot bushing
in the bore
of the crankshaft. The bushing is
pressed into the crankshaft and
FIG.
38-Typical Clulch Pilol
Bushing Wear Check
should not be loose. Inspect the
inner sur face of the bushing for wear
or a bell-mouth co nd it io n. Th e ID of
the bushing for all engines should be
0.6715-0.672 5 (F ig. 38). Replace the
bushing if worn or damaged.
Inspec t the pilot bearing, when
used, for ro ughness, evidence of
overheating or loss of lubricant. Re-
place if any of th ese conditions are
found.
REPAIRS
Dress minor imperfections with
an oilstone. Reface severely marred
journals.
Jf
the journals exceed the wear
limit, they shou ld be refinished to
size for the next undersize bearing.
Refinishi ng Journ als. Refinish the
journal to give the proper clearance
with the next undersize beari ng.
If
the journal will not "clean up" to
give the proper clearance with the
maximum undersize bearing avail-
ab le, rep lace the crankshaft.
Always reproduce the sa me jour-
nal shou lder radius that existed origi-
nally. Too small a radius may resu lt
in fatigue failure of the crankshaft.
Too large a radius will result in bear-
ing fai lure due
10
radiu s ride of the
bearing.
After refi ni shing the journals,
chamfer the oi l hole, th en polish the
journa l with a No , 320 grit pol ishing
clot h and engine o il. Crocus cloth
may also be used as a polishing agent.
CONNECTING RODS
The connecting rods and related
parts shou ld be carefully inspected
and checked for conformance to
specifications. Various forms of en-
gine wear caused by Ihese parts can
be readil y id entified.
A shiny surface on the pin boss
side of th e piston usually indicates
that a connecting rod is bent or the
pisto n pin ho le is not in proper rela-
tion to the piston skirt and ring
grooves.
Abnorma l co nnecting rod bearing
wear ca n be ca used by either a bent
connecting rod, a n im proper ly ma-
chined jou rn al, or a tapered connect-
ing rod bore.
Twisted connecting rods will not
create an eas il y iden tifi able wear pat-
tern, but badly twisted rods will dis-
turb th e actio n of the entire piston,
rings, and co nnectin g rod assembly
and may be the cause of excessive oi l
consumption.
CLEANING
Remove the bear in gs from the rod
and cap. Ident ify the bearings if they
are to be used again. Clean the con-
necting rod in so lvent, including the
rod bore and the bac k of the inserts.
Do not use a caustic clea ning solu-
tion. Blowout all passages with com-
pressed air.
INSPECTION
Inspect the con necting rods for
signs of fr actures and the bearing
bores for out-of-round and taper. It
the bore exceeds the maximum limi t
and / or if the rod is fractured, it
sho uld be replaced .
Check the piston pin to co nnecting
rod bushing clearance. Repl ace the
co nnecting rod if the bushing is so
worn that it cannot be reamed or
honed for an oversize pin.
Replace defective connecting rod
nuts and bolts.
After the connecting rods are as-
sembled to the piston, check the rods
for bend or twist on a suitable align-
ment fixture . Follow the instructions
of the fixture manufacturer. If the
bend and/or twi st is excessive, the
rod should be straightened or re-
placed.
PISTONS, PINS, AND RINGS
CLEAN ING
Remove deposits from the piston
surfaces. Clea n gum or varnish from
the pisto n skirt , pisto n pins, and rings
with solvent. Do not use a caustic
cleani ng solution or a wire brush to
clean pistons. Clea n the ring grooves
with a ring groove cleane r (Fig. 39).
M ake sure the oil rin g slots (or holes)
are c le an.
INSPECTION
Carefully inspec t the pistons fo r
fractures at the r ing lands, skirt, and
pin bosses, and for scuffed, rough, or
scored skirts. I f th e lower inner por-
tion of the ring grooves have high
steps, replace the piston . The step will
interfere with ring operatio n and
cause excessive r ing side clearance.
Spongy, eroded areas near the edge
of the piston top are usuall y caused
by detonation, or pre-ignition. A
shiny surface on the thrust surface of
the piston, offset from th e centerline
between the piston pin holes, can be
ca used by a bent con necting rod.
Replace pistons th at show signs of
excessive wear, wavy rin g lands, frac-
tures, and /or damage from detona-
tion or pre-i gnition.