Piston Pin Clearance; Camshaft; Camshaft Bearings; Connecting Rods - Ford LRG-423 Service Manual

01-24
Engine Service 01-24
SERVICE PROCEDURES (Continued)
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Clean and inspect the connecting rod as outlined
in this section.
Clean and inspect the piston and piston pin as
outlined in this section.
Using a suitable micrometer, measure the piston
pin where the piston pivots and in the center
where it is pressed into the connecting rod.
Using a suitable set of plug gauges or bore
gauge, measure the upper bore of the connecting
rod. An interference fit is required. If the bore is
oversize it will be necessary to install an oversize
piston pin. It is not necessary to rebore or ream
the connecting rod.
If the pin-to-rod fit is OK, measure the piston pin
bores in the piston.
Subtract the piston pin size from the piston pin
bore sizes. Pin-to-piston clearance is listed in the
specifications section.
If clearance is excessive it will be necessary to fit
an oversize piston pin.
To fit an oversize piston pin because either the
pin-to-connecting rod or pin-to-piston clearance
was excessive:
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Obtain an appropriate oversize piston pin.
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Hone or ream the piston pin bores in the piston
to obtain the correct clearance.
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It is not necessary to hone or ream the
connecting rod piston pin bore oversize.
Once pin, connecting rod, and piston are
correctly sized, assemble as outlined in Section
02.
Connecting Rods
Cleaning
Remove the bearings from the rod and cap. Identify
each bearing location if they are to be used again.
Clean the connecting rod in solvent, including the rod
bore and the back of the inserts. Do not use a caustic
cleaning solution. Blow out all passages with
compressed air.
Inspection
The connecting rods and related parts should be
carefully inspected and checked for conformance to
specifications. Refer to the specifications section.
Various forms of engine wear caused by these parts
can be readily identified.
A shiny surface on either pin boss i nside of the
usually indicates that a connecting
rod is bent.
ston
Abnormal connecting rod bearing wear can be caused
by either a bent connecting rod, worn or damaged
piston pin (6135), or a tapered connecting rod
crankshaft pin.
Twisted connecting rods can create an identifiable
piston skirt wear pattern, but badly twisted rods will
disturb the action of the entire piston, rings, and
connecting rod assembly and may be the cause of
excessive oil consumption.
Check the connecting rods for bend or twist on a
suitable alignment fixture. Follow the instructions of
the fixture manufacturer. If the bend and/or twist
exceeds specification, the connecting rod must be
replaced.
Inspect the connecting rods for signs of fractures and
the rod bearing bores for out-of-round and taper. If the
bore exceeds the recommended limits and/or if the
connecting rod is fractured, it should be replaced.
Piston Pin Clearance
Refer to Piston and Piston Pin Fit in this section.
Camshaft
Cleaning
1.
If not done as part of engine disassembly,
remove camshaft sprocket (6256) from camshaft
(6251) and camshaft from engine as outlined in
Section 02.
2.
Clean the camshaft in an appropriate solvent and
wipe it dry.
3.
Remove light scuffs, scores, or nicks from the
camshaft machined surfaces with an oil stone.
Inspection
Inspect the camshaft journals and lobes for scoring
and signs of abnormal wear.
Lobe pitting, except in the general area of the lobe toe,
is not detrimental to the operation of the camshaft. The
camshaft should not be replaced unless lobe lift loss
has exceeded the specifications or pitting has
occurred in the lobe lift area. Refer to Cam Lobes in
this section.
Camshaft Bearings
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Wipe bearing bore clean with a clean rag and
solvent. Dry with a clean rag.
Inspect for scoring and visible wear. Inspect
bearings for excessive wear. If visibly worn or
damaged, replace bearings. If one of the center
bearings is worn significantly more than the end
bearings, check camshaft for excessive runout.
Using suitable bore gauge or inside micrometer,
measure each bearing, 90 degrees apart, to
determine bearing size and out-of-round. Double-
check by measuring twice.
Check results against specifications in the
specification section. If bearings are out of
specifications, they will have to be replaced.
Check camshaft journals before replacing
bearings to determine if undersize bearings are
required.
If necessary, replace the bearings.