1940-1947 Harley-Davidson O.H.V. & Side Valve Engine Service Manual

Technical Scope for 1940–1947 Harley-Davidson Big Twin

• Covers the 1940–1947 Harley-Davidson O.H.V. and Side Valve Big Twin motorcycles, including E, EL, F, FL, U, UL, UH, and ULH engine configurations
• Original OEM publication Part No. 12022-44D, consolidated technical manual covering service, maintenance, and overhaul
• Contains 89 detailed illustrations, exploded-view diagrams, and electrical system schematics for vintage Big Twin mechanics
• 165 pages of factory-specified assembly tolerances, engine oiling diagrams, and electrical testing protocols
• File link appears in your order confirmation straight away
• OCR text layer lets you jump to a torque spec by keyword
• This 1940–1947 edition remains the primary reference for timing, fuel system, and chassis maintenance of the classic Harley-Davidson Big Twin line

Contents Overview

The 1940–1947 Harley-Davidson Big Twin service manual provides extensive technical coverage of the engine and drivetrain systems. Detailed chapters document troubleshooting, initial setup, and full engine overhaul processes for both O.H.V. and Side Valve architectures. You will find specific technical documentation on the ignition circuit breaker, carburetor adjustment, oil feed pump operation, and transmission shifting mechanics. The manual also details the maintenance and assembly of the fork, frame, saddle, and sidecar components.

Engine and Technical Specifications

This factory publication provides precise engine clearance and assembly data. Engine bore and stroke specifications are documented for the 61, 74, and 80 cubic inch models. Cylinder head bolt torque values are documented in a multi-stage sequence, with final-stage specifications listed in the overhaul section. The 1940–1947 Harley-Davidson Big Twin manual lists oil pressure settings at 15–35 lbs depending on the model and pump type. Valve clearance for the intake is listed at 0.04–0.05 mm in the cylinder head specification table. The Harley-Davidson Side Valve 74 engine displacement is 73.79 cubic inches as documented in the general specs table. Valve clearance for the exhaust is listed at 0.007–0.008 mm in the maintenance reference table. Reference what an OEM service publication covers to understand the technical depth provided in this document.

Note: This page is a contents overview for the manual. It does not provide repair or diagnostic instructions. An official 165-page Harley-Davidson OEM service manual covering 1940–1947 O.H.V. and Side Valve Big Twin models, documenting engine, drivetrain, electrical, and chassis specifications for the 1940s-era motorcycle production line.