Identification; Build Date Code; Short Engine Assembly; Oversize Or Undersize Components - Jeep J-10 Series 1982 Technical & Service Manual

the front. The crankshaft is supported by seven two-
piece bearings (inserts). The camshaft is supported by
four one-piece, line bored bearings.
The six-cylinder engine features a quench-type com
bustion chamber, which creates turbulance and fast
burning of the air/fuel mixture for good fuel economy.
Identification
Build Date Code
The engine Build Date Code is located on a machined
surface on the left side of the block (viewed from front)
between the No. 2 and No. 3 cylinders (fig. 1B-43).
The numbers in the code identify the year, month and
day that the engine was built.
The code letter identifies the cubic inch displacement,
carburetor type and compression ratio. The data are
decoded as listed in the Engine Build Date Code Chart.
Engine Build Date Code
Letter
Code
CID Carburetor
Compression
Ratio
C j 258
2V
8.6:01
1st
Character
(Year)
2nd and 3rd
Characters
(Month)
4th
Character
(Engine Type)
5th and 6th
Characters
(Day)
1-1981
2-1982
01 - 12 C
01 -31
EXAMPLE: 1 10 C 1! 60257
The example code identifies a 258 CID (4.2 liter) en
gine with 2V carburetor and 8.6:1 compression ratio that
was built on October 18, 1981.
Oversize or Undersize Components
Some engines may be built with oversize or undersize
components, such as oversize cylinder bores, undersize
crankshaft main bearing journals, undersize connecting
rod journals or oversize camshaft bearing bores. These
engines are identified by a letter code stamped on a boss
between the ignition coil and distributor (fig. 1B-45).
The letters are decoded as listed in the Oversize or Un
dersize Components chart.
SHORT ENGINE ASSEMBLY (SHORT BLOCK)
A service replacement short engine assembly (short
block) may be installed whenever the original engine
ENGINES 1B-31
Oversize or Undersize Components
Code
Letter
Definition
B
All cylinder bores
-0.010-inch
(0.254mm) oversize
M
All crankshaft main bearing journals
-0.010-inch
(0.254mm) undersize
P
All connecting rod bearing journals -0.010-inch
(0.254mm) undersize
C
All camshaft bearing bores •0.010-inch
(0.254mm) oversize
EXAMPLE: The code letters PM mean that the crankshaft main bearing
journals and connecting rod journals are 0.010-inch undersize.
6025S
DISTRIBUTOR
IGNITION
COIL
LPM I
. •
<* • i • ••
Fig. 1B-45 Oversize or Undersize Letter Code Location
block is worn or damaged beyond feasible repair. I:
consists of engine block, piston and rod assemblies and
crankshaft. The camshaft must be procured separately
and installed before engine is installed in a vehicle.
NOTE: Short engine assemblies have an S stamped on
the same surface as the build date code for
identification.
Installation includes transfer of component par:s
from the worn or damaged original engine. Follow the
appropriate procedures for cleaning, inspection, instal
lation and tightening as outlined in this chapter.
ENGINE MOUNTING
Resilient rubber cushions support the engine and
transmission at three points: at each side on the center-
line of the engine and at the rear between the transmis
sion extension housing and the rear suppor:
crossmember (fig. 1B-46). Replacement of a cushion may
be accomplished by supporting the weight of the engine
or transmission at the area of the cushion.