1958–1965 Scott McCulloch 3.6 HP–75 HP Outboard Motor Factory Service Manual (P/N 79088)

This nine-file PDF set brings together Scott-Atwater, Scott, and McCulloch material for the 1947 Model 473 and model-specific service data covering selected 1955–1967 outboards. The repair sections are best suited to experienced vintage-outboard mechanics and restorers who can identify an engine by model code and work from exploded assemblies, specification tables, and special-tool drawings; the Model 473 booklet and Johnson fundamentals guide add owner-level operating and care information.

• Model tables cover the McCulloch 3½/3.6 HP family (1955–65), 4 HP (1965–67), and 7½/9 HP (1960–67), along with Scott 5, 7½, 10, and 16 HP models (1955–59) and the 1947 Scott-Atwater Model 473 Deluxe Twin.

• Larger-engine coverage separates Scott 12/McCulloch 14 HP (1960–67), Sport Scott/McCulloch 28 HP (1958–67), and Royal Scott/McCulloch 45/450 OX and Flying Scott/McCulloch 75 builds (1958–65), including heavy-duty work-motor and racing configurations.

• Carburetor and fuel-system repair includes Carter, Tillotson, Marvel-Schebler, and Walbro units, with disassembly, inspection, float and needle adjustment, fuel-pump service, reed-valve checks, and multi-carburetor synchronization.

• Electrical sections cover flywheel magnetos, breaker-point and distributor timing, starter-generator service and diode testing, battery-ignition systems, and manual- versus electric-start differences, supported by wiring and timing information for fault isolation.

• Powerhead procedures include removal, disassembly, internal inspection, and reassembly. Cooling-system material covers rubber-rotor and impeller pumps, Bail-A-Matic dual-pump service, thermostats, water passages, and the air-cooled 4 HP powerhead’s water-cooled exhaust leg.

• Lower-unit repair distinguishes direct-drive and gear-shift arrangements, Standard and Weedless Drive units, and the Custom Flying Scott gearcase, including seal and bearing work, gear and clutch-dog inspection, end-play and backlash checks, and shim selection.

• Drawing support includes No. 79088’s 13 numbered exploded-view groups and its Powerhead and Bail-A-Matic and Propeller views, plus a starter-generator wiring diagram, rubber-impeller water-pump schematic, three-cylinder distributor timing diagram, and Custom Flying Scott gearcase exploded view.

Nine-File Set and Publication Details

The set totals 184 PDF pages in nine files: a 29-page 3½–16 HP service-data section; a 14-page 12/14/28 section; a 22-page 45/75 section; the 22-page McCulloch Illustrated Parts List No. 79088; a 12-page Scott 3985 Series parts catalog; two 12-page scans of the Model 473 booklet; a 12-page Champion tuning and troubleshooting guide; and a 49-page Johnson fundamentals book. The two Model 473 files reproduce the same 12-page publication in different scans and orientations, leaving 172 pages of distinct source content.

Published by McCulloch Corporation in 1963, No. 79088 is the illustrated parts reference for manual-start Model 64300750 and long-shaft Model 64300760. It identifies component placement across the housing, starter, magneto, powerhead, carburetor, lower casing, lower unit, fuel system, boat bracket, steering handle, and extended-shaft assemblies.

Source Scope and Repair Depth

This is a mixed-source technical set, not one factory service manual. No. 79088 and the Scott-Atwater booklets are manufacturer literature. The three multi-model service-data sections state that their publication was not authorized by the manufacturer; they use manufacturer illustrations but should be treated as third-party service information. The Champion booklet supplies general marine ignition and spark-plug troubleshooting, while Johnson’s Know Your Outboard Motor explains operating, care, cooling, propeller, and diagnostic fundamentals and expressly is not an instruction book or service manual.

Coverage is organized by model code and year rather than one continuous serial-number range. The service data distinguishes manual and electric starting, direct-drive and gear-shift lower units, Standard and Weedless Drive versions, OX work motors, and the Custom Flying Scott racing lower unit. It also records model-year changes in piston, bearing, ignition, and gearcase construction. Fuel lubrication is year- and oil-specific: the 100:1 mixture applies to 1963-and-later engines when McCulloch 100:1 Oil is used; earlier engines or other oils require the ratio specified for that application.

Special Tools, Specifications, and Cautions

Custom Flying Scott lower-unit repair calls for dedicated tools such as the T-5350 driveshaft bearing-cap wrench, T-5393 prop-shaft seal protector, and T-5403 reverse-gear assembly tool. The specification coverage includes component-specific torque tables, spark-plug and breaker-point settings, compression data, carburetor adjustments, piston and cylinder clearances, shaft end play, gear backlash, lubricant requirements, and wear limits.

The McCulloch 4 section warns that the connecting-rod bearing service pack includes an extra needle roller; installing every roller supplied can bind and damage the rod bearing. On the Custom Flying Scott lower unit, losing the indexed shim arrangement or pinion-spline position can alter backlash and damage the gear train.

Vintage magneto, distributor, and starter-generator work involves high voltage and exposed rotating parts; disconnect the spark-plug leads and secure the powerhead before inspection.