International Harvester Farmall A, AV, B, BN & U-2 Power Unit Service Manual 1939–1953 (P/N 57722 D)

• Covers 1939–1953 International Harvester Farmall A, AV, B, BN, International A tractors, and the U-2 Power Unit.
• OEM Publication P/N 57722 D.
• Features 80 detailed illustrations, including exploded views of the engine, carburetor, governor, transmission, and differential assemblies.
• Serves as the primary technical archive for restoring and maintaining the International Harvester A/B series tractor range.
• Details critical assemblies including the magneto ignition system, gear-type oil pump, engine clutch, external contracting brakes, final drive, steering gear, belt pulley, and power take-off.
• Outlines step-by-step instructions for timing the magneto, synchronizing the governor, adjusting bevel gears, relining the brakes, adjusting the clutch, rebuilding the carburetor, and disassembling the steering gear, helping you avoid costly specialized workshop fees.

Engine and Fuel System Architecture

This 71-page technical PDF publication details the maintenance and assembly parameters for the 4-cylinder wet-sleeve engine used across the Farmall A, B, and U-2 Power Unit lineup. It outlines the complete engine teardown and repair process, providing mechanics with exact specifications for connecting rods, bearings, crankshaft tolerances, and valve train geometry. Fuel system content focuses heavily on the Zenith and Marvel Schebler carburetor units. You will find breakdown and reassembly data alongside jet identification charts for various fuels, including gasoline, kerosene, and distillate options. Because working on vintage heavy machinery carries inherent physical risks, reviewing these factory specifications prior to wrenching is vital to ensure a safe shop environment and prevent equipment damage.

Drivetrain, Electrical, and Specification Highlights

The publication includes detailed transmission speed charts and electrical wiring schematics for the starter and generator systems. Visual references such as dimensional drawings, standard net power curves, part throttle fuel consumption curves, ignition wiring charts, and cross-section views provide essential guidance. It highlights bevel gear adjustment parameters, specifically outlining tooth contact patterns for proper pitch line intersection. Engine specification tables document cylinder head bolt torque strictly at 65 ft. lbs. Valve guide data specifies intake valve stem clearance at 0.0015 to 0.0035 inches. The manual also lists complete cooling system capacities, noting 3-3/8 gallons for these specific units. Utilizing this exact factory data ensures precise alignment of internal components, preventing catastrophic gear or bearing failure under heavy drawbar loads and saving you from an expensive repair bill at the dealership. This documentation delivers the exact dimensional data required for accurate bench work and reliable field service.