Service manual
12C/12D
TWO
SERVICE
DATA
I
STANDARDS
AND
LIMITS
Component
Specified
Value
I
Standard
Repair
Limit
inches(mm) inches(mm)
---
COMPRESSION
I
TIMING
Cylinder
Compression
...........
398.16
psi
at
280
rpm
................
355.5
psi
·Pressure
(28
kg/em')
(25
kg/em')
Difference
between
...........................
35.55
psi
Cylinders
(max)
(2.5
kg/em')
Fuel
Injection
Order
-12C/D
Two
.........
1-
2
Injection
liming
at
BTDC
on
compression
stroke
.....................
19°
±
1.5
............................
19°
± 2
Spill
liming
(static)
Injector
Spray
Pressure
..............
1990
psi±
140.0
(140
±
10.0
Kg/cm2)
CYLINDER
HEAD
Bottom
Surface
Distortion
........
within
0.002
(0.05)
..................
0.004
(0.1)
Valve
Guide
1.0
................................
0.260
(6.6)
(Intake
&
Exhaust)
Valve
Seat
Angle
...................................
.45°
(Intake
&
Exhaust)
Valve
Seat
Width
..................
0.051
-
0.071
(1.3
-
1.8)
............
0.004
(0.1)
(Intake
&
Exhaust)
Valve
Seat
Sinkage
.....................................................
-0.039
(-1mm)
Service
Limit
Valve
Clearance
...........................
O.o10
(0.25)
Cold
(Intake
&
Exhaust)
VAlVES
Valve
Head
Diameter
(lntake)
.........
1.051
(26.7)
Valve
Head
Diameter
(Exhaust)
......
0.972
(24.7)
Overall
Length
...................................
3.701
(94)
Stem
O.D
..........................................
0.260
(6.6)
Stem
to
Guide
Clearance
(Intake)
.............................................
1.051
(26.7)
Stem
to
Guide
Clearance
(Exhaust)
..........................................
0.972
(24.7)
Valve
Contact
Width
.................................
3
..................................
1.3
-
1.8
Valve
Face
Angle
....................................
.45°
Valve
Head
Thickness
......................
0.039
(1.0)
..............
:·
.........
0.019
(0.5)
(Margin
Width)
·,.
Valve
Head
Sinkage
........................
O.o19
(0.5)
........................
0.591
(1.5)
(from
cylinder
head
to
bottom
face)
Valve
Spring
Free
Length
..............................
1.595
(
40.5)
......................
1.54
7
(39.3)
Preload/Installed
Length
....
13.095
lbs/1.398
in
......................
-15%
(5.94
kg/35.5mm)
........................................
32.7161bs/1.102
in
......................
-15%
(14.84
kg/28mm)
Squareness
..............................................
2°
......................................
3°
TIMING
GEARS
Backlash
between
gears
in
Mesh
0.0003-
0.0005(0.01
-
0.14)
..........
0.012(0.3)
Idler
Gear
Bushing
-
Clearance
between
Bushing
and
Shaft
0.001
- 0
01
0(0.03
-
0.07)
..........
0.0078(0.2)
Component
Specified
Value
I
Standard
Repair
limit
lnches(mm)
inches(mm)
ROCKER
ARM
Interior
Diameter
...............................
0.047
(12)
Rocker
Arm
to
Shaft
Clearance
................................................
-0.008
(-0.2)
CYLINDER
BlOCK
Camshaft
Hole
Diameter
Front...
.........................................
1.654
(42)
,
..
Ball
Bearing
Hole
No.2
..........................................
1.339
(34)
No.
3
..........................................
1.299
(33)
Rear
............................................
1.299
(33)
CYLINDER
BORE
.
Bore
Size
........................................
2.992
(76mm)
....................
+0.008(+0.2)
Oversize
Finish
ToleranceO
-
0.001
(0-0.03)
for
each
oversize
Cylindricity
............................
:
...
within
0.0004
(0.01)
Gasket
Fitting/
...........................
within
0.0020
(0.05)
................
0.004
(0.1)
Surface
Distortion
PISTON
Type
.................................................
Solid
Type
Materiai
.........................................
Aiuminum
Alloy
Outside
Diameter
(Skirt
End)
..........
2.992
(76)
Clearance
to
Cylinder
......
0.0028-
0.0079(0.071
-
0.084)
........
0.001
(0.3)
Oversize
......
:
.................................
0.01,
0.02.
0.03
(0.25,
0.50,
0.75)
Protrusion
From
Cylinder
................
0.035
(0.9)
Block
Top
Surface
PISTON
PIN
(See
note
on
next
page)
Type
..........................................
Semi-floating
Type
Outside
Diameter.
..................
0.709
(18)
Early
Models
................................................
0.825
(21)
Late
Models
Piston
Pin
to
Piston
Clearance
.................................................
0.003
(0.08)
Piston
Pin
to
Connecting
Rod
Clearance
Press-fit
Load
.............
2204.6
±
1102.31bs
(1000
±
500
kg)
PISTON
RINGS
(See
note
on
next
page)
Number
of
Rings
Compression
(2)
No.
1
......................
Chrome
plated,
semi-keystone
type
No.
2
............................................
Tapered
Oil
(1)
......................
Chrome
plated
with
Coil
expander
Ring
Sid~
Clearance
Compression
No.
1
......................................................................
0.3
Compression
No.
2
......
0.002
-
0.004
(0.05
-
0.09)
.........
.0.008
(0.2)
Oil
...............................
.0.001
-
0.002
(0.03
-
0.07)
..........
0.008
(0.2)
Ring
Gap
(All
Rings)
...........
0.006-
0.016
(0.15-
0.40)
................
(1.5)
Engines & Generators
47