Perkins 1106C Genset Systems Operation Testing And Adjusting page 69

KENR6931
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New connecting rod assemblies that are the
correct grade of length must be installed. Refer to
"Length Of The Connecting Rod".
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New piston pin bearings must be bored after
installation in the original connecting rods. Refer
to "Piston Pin Bearings".
Note: When the piston pin is installed, always install
new retaining rings on each end of the piston pin. If
the piston pin cannot be removed by hand, heat the
piston to a temperature of 45° ± 5 °C (113° ± 9 °F) in
order to aid the removal of the piston pin. Heating
the piston to this temperature may also aid the
installation of the piston pin.
Length of The Connecting Rod
The connecting rod length (CRL) is the length of the
connecting rod. Refer to Table 10 for each grade of
length of connecting rod.
In order to ensure that the piston height above the
cylinder block is correct, three grades of connecting
rods "F" to "L" are used during manufacture at the
factory. Replacement connecting rods are available
in three grades. These grades of connecting rod
are "F" to "L". The grade of length is identified by a
letter or a color which is marked on the side of the
connecting rod. The longest grade is marked with the
letter "F". The shortest grade is marked with the letter
"L". The difference in length between each grade of
connecting rods is the following value: 0.076 mm
(0.0030 inch)
The grade of length of a connecting rod is determined
in the factory by machining an eccentric hole in a
semi-finished piston pin bushing. Therefore, the
grade of length is determined by the position of the
center of the hole in the piston pin bearing.
If the connecting rod must be replaced, a new
connecting rod assembly must be purchased and
installed. Refer to Table 10 for more information.
A new piston pin bearing is installed in the new
connecting rod at the factory. The bore of the piston
pin bearing is reamed to the correct eccentricity.
Piston Pin Bearings
Note: This procedure requires personnel with the
correct training and the use of specialized equipment
for machining.
If the piston pin bearing requires replacement but the
original connecting rod is not replaced, the following
procedures must be performed:
1. Determine the grade of length of the connecting
rod. Use one of the following characteristics:
Testing and Adjusting Section
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The mark
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The color
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Measuring the length
2. Ensure that the connecting rod is aligned parallel
and that the connecting rod is not distorted. Refer
to "Distortion Of A Connecting Rod" in this service
module.
3. Remove the piston pin bearing from the connecting
rod. Install a new bearing in the connecting rod.
The new bearing is partially finished. The new
bearing must be bored off-center to the correct
diameter. This off-center position is determined by
the grade of length of the connecting rod. Refer to
Table 10. The correct diameter of the bore in the
piston pin bearing is given in the Specifications
Module, "Connecting Rod".
Surface finish of the bored hole in the piston pin
bearing .................................. Ra 0.8 micrometers
4. Machine the ends of the piston pin bearing to the
correct length. Remove any sharp edges. Refer to
the Specifications Module, "Connecting Rod".
5. If the grade of length of the connecting rod
is changed, the letter that is stamped on the
connecting rod must be removed. Etch a letter
that is for the new grade of length on the side of
the connecting rod.
Note: Do not stamp a new letter on the connecting
rod. The force of stamping may damage the
connecting rod.
Table 10 references the following information: Grade
of letter of the connecting rod, the color code of the
connecting rods, and the lengths of the connecting
rods.
Table 10
Length Grades for Connecting Rods
Grade Letter Color Code
F Red
J Green
L Blue
Measure The Length Of The Connecting
Rod
If the mark or the color of the grade of length cannot
be observed on the connecting rod, perform the
following procedure:
69
Length Of The
Connecting Rod (CRL)
161.259 to 161.292 mm
(6.3488 to 6.3501 inch)
161.183 to 161.216 mm
(6.3458 to 6.3471 inch)
161.107 to 161.140 mm
(6.3428 to 6.3441 inch)