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
MARCH 1982 6-3
PART NAME FEATURE NEW DIMENSION
(INCHES)
Camshaft Journal Diameter (4) Permold Crankcase
Journal Diameter (4) Sandcast Crankcase
0.9980 - 0.9990
1.2480 - 1.2490
Hydraulic Valve Tappets Outside Diameter 0.9990 - 0.9995
Crankcase Camshaft Bearings Dia. Permold Crankcase
Camshaft Bearings Dia. Sandcast Crankcase
Crankshaft Bearing Bore in Crankcase Std.
Crankshaft Bearing Bore in Crankcase "B"
Configuration. Rear and Intermediate
Bearings Only.
Tappet Guides Dia.
Governor Driven Gear Bearing Dia.
Starter Shaft Needle Bearing Hole Dia.
1.0000 - 1.0010
1.2500 - 1.2510
2.5625 - 2.5635
2.8160 - 2.8170
1.0005 - 1.0015
0.8750 - 0.8760
0.9990 - 1.0000
Starter Worm Drive Shaft Small End Diameter
Needle Bearing Hole in Starter Adapter
0.5615 - 0.5625
0.7485 - 0.7495
Starter Shaftgear Front Journal Diameter
Knurled Drum Diameter
Clutch Drum Support Dia. Sandcast Crankcase
Clutch Drum Support Dia. Permold Crankcase
0.7495 - 0.7500
1.9310 - 1.9320
0.7870 - 0.7880
0.9995 - 1.0000
Starter Clutch Drum Inside Diameter Sandcast Crankcase
Inside Diameter Permold Crankcase
0.7900 -0.7910
1.3115 - 1.3125
Starter Clutch Spring Outside Diameter
Inside Diameter
2.3740 - 2.3760
1.9380 - 1.9400
Starter Drive Adapter Sleeve Front End I.D. 2.3380 - 2.3430
Oil Pump Driver Gear Shaft Diameter 0.5600 - 0.5605
Oil Pump Driven Gear Shaft Assembly Hole Dia. Sandcast Crankcase
Shaft Assembly Hole Dia. Permold Crankcase
0.5620 - 0.5630
0.6870 - 0.6880
Oil Pump Housing and
Shaft Assembly
Driven Gearshaft Dia. Sandcast Crankcase
Driven Gearshaft Dia. Permold Crankcase
Driver Gearshaft Hole Diameter
Gear Chamber Depth Permold Crankcase
Gear Chamber Depth Sandcast Crankcase
0.5015 - 0.5025
0.5640 - 0.5650
0.5620 - 0.5630
1.3275 - 1.3290
2.6235 - 2.6250
Magneto Drive Gears Shaft Diameter 0.8120 -0.8130
Magneto and Accessory
Drive Adapter
Bushing Inside Diameter 0.7925 -0.7975
Idler Gear Assembly Bushing Inside Diameter Sandcast Crankcase 0.7900 -0.7950
Idler Gear Front Bushing Bushing Inside Diameter Permold Crankcase 0.5600 -0.5610
Idler Gear Flanged Bushing Bushing Inside Diameter Permold Crankcase 0.5010- 0.5020
Idler Gear Support Pin Gear Support Diameter Sandcast Crankcase 0.8095 -0.8105
Idler Gear Large Diameter Permold Crankcase
Small Diameter Permold Crankcase
0.5580 -0.5590
0.4990 -0.5000
* Measure piston diameters at right angles to pin bore.