Operating instructions
Table Of Contents
- 1 Introduction
- 2 General Description
- 3 Special Tools and Equipment
- 4 Disassembly
- 5 Cleaning, Repair and Replacement
- 6 Inspection
- Definitions
- Magnetic Particle Inspection
- Critical New Part Dimensions
- Fluorescent Particle Inspection
- Dimensional Inspection
- Protective Coatings
- Crankcase Inspection
- Crankshaft Inspection
- Camshaft Inspection
- Connecting Rod Inspection
- Gear Inspection
- Piston Inspection
- Cylinder Inspection
- Inspection Chart
- Crankcase Stud Heights
- Mag Particle Inspection Procedures
- Table of Limits
- Torque Specifications
- General Torques
- Table of Limits Chart
- 7 Assembly of Subassemblies
- 8 Final Assembly and Test
- 9 IO-520-M
- 10 IO-520-BB, CB and MB

6-23
New Parts
Ref.
No.
Chart
No.
Model Description
Serviceable
Limit
Min. Max.
137
138
139
140
141
142
143
144
145
146
147
148
3
4
4
2
3
3
2
3
2
2
3
2
3
2
2
1
1
1
1
C
All
All
S
P
P
S
P
S
S
P
S
P
All
S
All
All
All
All
Tachometer drive gear and tachometer
driven gear ...........................................................Backlash:
Starter shaftgear and crankshaft gear. ...................... Backlash:
Starter worm wheel gear and worm gear. ................. Backlash:
Governor drive gear and governor driven gear. ........Backlash:
Governor drive gear and governor driven gear. ........Backlash:
Alternator face gear in engine. .................................. Backlash:
SPRING TEST DATA
Oil temperature control valve 0.16 inches
minimum travel at .......................................... Temperature:
Oil temperature control valve 0.090 inches
minimum travel at .......................................... Temperature:
Oil temperature control valve to flow
4 gpm of oil between. ......................................Oil Pressure:
Oil temperature control valve must close
between ....................................................Oil Temperature:
Oil temperature control valve must close
between ....................................................Oil Temperature:
Oil temperature control valve at oil temperature 180°
must not open below ............................................ Pressure:
Oil temperature control valve at oil temperature 180°
must not open below. ........................................... Pressure:
Relief valve spring compressed to 1.25 in. length ............Load:
Oil filter by-pass valve spring in pump
compressed to 1.09 inch length. .................................Load:
Inner valve spring No. 631521 (compressed to
1.230 inch length) .......................................................Load:
Inner valve spring No. 631521 (compressed to
1.746 inch length) .......................................................Load:
Outer valve spring No. 631520 (compressed to
1.275 inch length) .......................................................Load:
Outer valve spring No. 631520 (compressed to
1.791 inch length) .......................................................Load:
0.012
0.016
0.025
0.009
0.012
0.012
--
--
--
--
--
18 psi
18 psi
20 Ibs.
5.0 Ibs.
82 Ibs.
29 Ibs.
110 Ibs.
46 lbs.
0.004
0.008
0.009
0.002
0.004
0.002
135°
120°
18 psi
171°
168°
--
--
32 Ibs.
5.6 Ibs.
87 Ibs.
32 Ibs.
117 Ibs.
49 lbs.
0.008
0.012
0.013
0.006
0.008
0.009
173°
170°
23 psi
175°
172°
--
--
37.5 Ibs.
--
97 Ibs.
38 Ibs.
133 Ibs.
55 lbs.
P Permold crankcase.
S Sandcast crankcase.