1940-1947 Harley-Davidson O.H.V. & Side Valve Engine Service Manual • Part No. 12022-44D

1940–1947 Harley-Davidson Big Twin: Complete Technical Reference

Working on vintage V-twins requires strict adherence to factory tolerances and proper tooling to prevent critical engine damage or personal injury. Always verify specifications against your specific engine casting before final assembly.

Looking for exact factory clearances for your Knucklehead or Flathead build? This OEM-sourced publication delivers the precise engineering data you need for your daily workshop routine.

• Covers 1940–1947 O.H.V. and Side Valve Big Twin models, including E, EL, F, FL, U, UL, UH, and ULH configurations.
• Direct reproduction of OEM Part No. 12022-44D, consolidating 165 pages of critical service, maintenance, and overhaul data.
• Features 89 exploded-view diagrams alongside detailed vintage electrical schematics.
• Fully searchable OCR text layer allows you to instantly locate torque specs right on the bench.
• Available as an instant PDF download directly after checkout so you can get straight back to wrenching.

Inside the Documentation

This manual provides extensive technical coverage of vintage engine and drivetrain systems. You will find detailed walkthroughs of initial setup procedures alongside full engine overhaul parameters for both overhead and side valve architectures. Need the exact specifications for the oil feed pump or ignition circuit breaker? It is all documented here. The guide also details carburetor adjustments, transmission shifting mechanics, and the assembly of essential chassis components like the fork, frame, saddle, and sidecar.

Engine Clearances and Specifications

Precision is everything when bringing a 1940s Big Twin back to life. This factory publication maps out exact engine bore and stroke dimensions for the 61, 74, and 80 cubic inch platforms. Cylinder head bolt torque values are documented in a precise multi-stage sequence.

The technical depth covers all critical tolerances. For example, oil pressure settings are strictly defined at 15–35 lbs, depending on your specific model and pump type. Intake valve clearances sit at 0.04–0.05 mm, while exhaust valve tolerances require a tighter 0.007–0.008 mm. Displacement for the Side Valve 74 is officially documented at 73.79 cubic inches. These are the exact numbers required to ensure your restoration performs exactly as intended.