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Wisconsin ABN Engine

The Wisconsin Model ABN is a heavy-duty, single-cylinder, four-cycle air-cooled industrial engine introduced in 1949 to replace the earlier Model AB. Engineered for rigorous commercial, agricultural, and industrial service, the ABN features an L-head (side-valve) design with a higher compression ratio than its predecessor. This modification allowed the engine to optimize output using the higher-octane fuels available in the mid-20th century. Known for its cast-iron construction and robust build quality, the ABN delivers high torque at lower operating speeds and uses a traditional mechanical or centrifugal flyball governor to maintain steady engine speeds under load fluctuations.

The engine employs a side-valve configuration (L-head format), where both the intake and exhaust valves are positioned vertically within the engine block adjacent to the cylinder bore. Valves are mechanically operated by a camshaft driven directly via timing gears off the main crankshaft. The engine profile utilizes a 2.50-inch bore and a 2.75-inch stroke, providing a total displacement of approximately 13.49 cubic inches (221 cc).

The fuel system relies on a gravity-fed or fuel-pump assisted design drawing regular automotive gasoline through an inline sediment bowl strainer. A balanced, side-draft or up-draft Marvel-Schebler (typically VH series) or Zenith carburetor automatically meters the correct fuel-to-air ratio across all varying speeds and load conditions. Air filtration is handled through an external oil-bath style air cleaner assembly to prevent airborne contaminants from entering the induction tract.

Lubrication is managed via a constant-level splash type system. An internal mechanical plunger pump operates off the camshaft to continuously deliver oil to a designated trough located directly beneath the connecting rod. The dipper on the connecting rod cap splashes oil from this trough to lubricate internal moving parts, including the cylinder walls, wrist pin, and main bearings. Total crankcase capacity is 1.25 pints.

Thermal regulation is achieved through a forced air-cooled system. A combination fan-flywheel draws air through a sheet metal blower shroud. This air is divided, metered, and precisely directed over the deeply finned cylinder block and cylinder head by integrated ducts and internal baffle plates to ensure uniform heat dissipation.

General Technical Data

Engine Specifications

Engine Model ............... Wisconsin ABN
Engine Type ............... Single-cylinder 4-cycle horizontal shaft L-head gasoline
Cylinder Configuration ............... Vertical single cylinder
Cylinder Bore, in (mm) ............... 2.50 (63.5)
Piston Stroke, in (mm) ............... 2.75 (69.8)
Total Displacement, cu.in (cc) ............... 13.5 (221.2)
Maximum Rated Power, hp (kW) ............... 4.6 (3.43) at 3600 rpm
Continuous Rated Power, hp (kW) ............... 3.0 (2.24) at 2400 rpm
Intermediate Rated Power, hp (kW) ............... 3.4 (2.5) at 2800 rpm
High Speed Rated Power, hp (kW) ............... 4.0 (2.98) at 3200 rpm
Minimum Operating Speed, rpm ............... 1200
Maximum Governed Speed, rpm ............... 3600
Low Idle Speed Range, rpm ............... 1000-1200
Maximum Peak Torque, lb-ft (Nm) ............... 7.4 (10.1) at 2200 rpm
Compression Ratio Rating ............... 5.1:1-5.5:1
Cylinder Block Material ............... High-tensile close-grained cast iron alloy
Cylinder Head Design ............... Cast iron L-head config with deep cooling fins
Crankcase Material ............... Heavy-duty cast iron integrated with cylinder block
Flywheel Material ............... Balanced cast iron with integrated cooling fan blades
Camshaft Construction ............... Drop-forged steel alloy with hardened cam lobes and gears
Valve Valvetrain Arrangement ............... Side-valve L-head layout parallel to cylinder bore
Intake Valve Head Material ............... Heat-resisting alloy steel
Exhaust Valve Head Material ............... Premium Stellite-faced heat-resistant steel alloy
Cooling System ............... Heavy-duty forced-air circulation via integral flywheel fan blower
Lubrication System ............... Splash lubrication system with mechanical plunger pump
Oil Pump Type ............... Reciprocating plunger style oil pump driven by camshaft eccentric
Oil Distribution Network ............... Integral internal passages routing oil directly to troughs
Air Filter Type ............... Oil-bath type air cleaner with wire mesh element
Ignition System ............... High-tension magneto unit driven directly from crankshaft
Magneto Manufacturers ............... Wico, Fairbanks Morse, or Bendix Stromberg assemblies
Spark Advance Angle Config ............... Fixed 20 deg

Fuel System

Fuel Induction Principle ............... Atmospheric pressure differential updraft carburetion layout
Carburetor Manufacturer Options ............... Zenith Model 87B5 or Marvel-Schebler VH series
Alternative Carburetor Options ............... Bendix Stromberg OH series or UR-3/4 assemblies
Choke Actuation System ............... Manual cable-controlled offset butterfly valve disk
Main Metering Control Unit ............... Adjustable needle valve with external knurled thumb screw
Idle Mixture Regulation ............... Air-bleed adjustable needle spring-loaded screw assembly
Carburetor Throttle Shaft Bushings ............... Precision-machined bronze insert sleeves pressed into body
Fuel Feed Method ............... Gravity-fed fuel flow from elevated top-mounted fuel container
Alternative Fuel Delivery Method ............... Mechanical diaphragm fuel pressure pump
Fuel Filtration Assembly ............... Glass-bowl sediment bulb fuel strainer with integrated mesh screen
Fuel Strainer Shut-Off Mechanism ............... Manual brass rotary needle valve built into strainer head
Standard Fuel Reservoir Volume, gal (L) ............... 1.000 (3.785)
Governor System Mechanism ............... Centrifugal mechanical flyweight type operating in oil bath
Governor Adjustment Control ............... Variable speed external lever assembly with tension spring
Fuel Tank Construction Material ............... Heavy-gauge lead-coated terneplate sheet steel alloy
Fuel Tank Filler Cap Architecture ............... Vented steel cap with internal splash baffle assembly
Fuel Delivery Pipeline Material ............... Annealed seamless copper tubing or flexible reinforced fuel hose
Fuel Delivery Pipeline Thread Connections ............... 1/8 in NPT internal thread fitting connectors
Carburetor Float Chamber Material ............... Cast iron or die-cast zinc alloy housing structure
Carburetor Float Design ............... Dual-gilled soldered brass pontoon float with hinge pin
Carburetor Float Needle Material ............... Precision-ground viton rubber tip or solid brass needle seating
Carburetor Main Jet Bore Diameter, in (mm) ............... 0.038 (0.965)
Carburetor Idle Jet Bore Diameter, in (mm) ............... 0.022 (0.558)
Carburetor Venturi Inside Diameter, in (mm) ............... 0.687 (17.449)
Fuel System Minimum Octane ............... 74 regular low-lead or unleaded gasoline
Fuel System Recommended Octane ............... 90 or higher regular gasoline for optimal clean combustion
Recommended Fuel Grade ............... Standard regular gasoline without alcohol additives
Maximum Fuel Line Static Pressure, psi (kPa) ............... 2.5 (17.2)
Air Cleaner Intake Opening Size, in (mm) ............... 1.25 (31.75)
Air Cleaner Housing Volume, pt (L) ............... 0.50 (0.24) engine oil reservoir capacity
Air Cleaner Filtration ............... Multi-layered crimped steel wire mesh condensing element
Governor-to-Carburetor Linkage Design ............... Solid steel rod wire with anti-backlash tension spring
Throttle Valve Shaft Clearance Tolerance, in (mm) ............... 0.001-0.003 (0.025-0.076)
Float Setting Distance Clearance, in (mm) ............... 1.18 (30.15)
Fuel Drain Cock Specification ............... Threaded brass needle plug at base of carburetor bowl

Dimensions and Weight

Overall Height, in (mm) ............... 18.5 (470)
Overall Width, in (mm) ............... 15.2 (385)
Overall Length, in (mm) ............... 14.7 (375)
Dry Weight, lbs (kg) ............... 76 (34.5)
Operating Weight, lbs (kg) ............... 83 (37.6)

Maintenance Data

Service Information

Spark Plug Type ............... Champion D16 or equivalent
Spark Plug Gap, in (mm) ............... 0.030 (0.762)
Breaker Point Gap, in (mm) ............... 0.015 (0.381)
Distributor Point Gap, in (mm) ............... 0.020 (0.508)
Intake Valve Clearance, Cold, in (mm) ............... 0.008 (0.203)
Exhaust Valve Clearance, Cold, in (mm) ............... 0.014 (0.355)

Engine Oil

Engine Oil Type .................. SAE 30, SAE 20W, or SAE 10W
API Service Classifications ......................... SE, SF, SG, or CC
Crankcase Oil Maximum Capacity, pt (L) ............... 1.25 (0.59)
Reduction Gearcase Fluid Capacity, pt (L) ............... 0.50 (0.24)

Service Intervals

Change engine oil ............... Every 50 hours
Inspect air cleaner ............... Every 8 hours
Service air cleaner ............... Every 50 hours
Clean fuel strainer ............... Every 50 hours
Valve clearance adjustment ............... Every 150 hours
Fuel system inspection ............... Every 100 hours
Clean spark plug ............... Every 100 hours
Replace spark plug ............... Every 300 hours
Clean cooling fin ............... Every 8 hours
Flush/Clean fuel tank ............... Every 500 hours
Change reduction gear oil ............... Every 500 hours

Service Specifications

Cylinder Bore Inside Diameter, in (mm) ............... 2.500-2.501 (63.500-63.525)
Cylinder Bore Out-of-Round Limit, in (mm) ............... 0.003 (0.076)
Cylinder Bore Maximum Taper, in (mm) ............... 0.004 (0.101)
Connecting Rod Total Center-to-Center Length, in (mm) ............... 5.000 (127.000)
Connecting Rod Journal Bore Inside Diameter, in (mm) ............... 1.3760-1.3765 (34.9504-34.9631)
Connecting Rod Bearing-to-Journal Clearance, in (mm) ............... 0.0010-0.0025 (0.0254-0.0635)
Connecting Rod Side Clearance, in (mm) ............... 0.004-0.008 (0.101-0.203)
Connecting Rod End Small Bore Inside Diameter, in (mm) ............... 0.6255-0.6260 (15.8877-15.9004)
Crankpin Journal Outside Diameter, in (mm) ............... 1.3745-1.3750 (34.9123-34.9250)
Crankshaft Main Bearing End Play, in (mm) ............... 0.002-0.004 (0.050-0.101)
Piston-to-Cylinder Wall Clearance, in (mm) ............... 0.0035-0.0050 (0.0889-0.1270)
Piston Pin Bore Inside Diameter, in (mm) ............... 0.6250-0.6253 (15.8750-15.8825)
Top Ring Groove Width, in (mm) ............... 0.115 (2.921)
Second Ring Groove Width, in (mm) ............... 0.115 (2.921)
Third Ring Groove Width, in (mm) ............... 0.115 (2.921)
Oil Ring Groove Width, in (mm) ............... 0.145 (3.683)
Top Ring End Gap, in (mm) ............... 0.007-0.015 (0.177-0.381)
Second Ring End Gap, in (mm) ............... 0.007-0.015 (0.177-0.381)
Third Ring End Gap, in (mm) ............... 0.007-0.015 (0.177-0.381)
Oil Ring End Gap, in (mm) ............... 0.007-0.017 (0.177-0.431)
Top Ring Groove Side Clearance, in (mm) ............... 0.0020-0.0035 (0.0508-0.0889)
Second Ring Groove Side Clearance, in (mm) ............... 0.0015-0.0030 (0.0381-0.0762)
Third Ring Groove Side Clearance, in (mm) ............... 0.0015-0.0030 (0.0381-0.0762)
Cylinder Head Flatness Warpage, in (mm) ............... 0.003 (0.076)
Intake Valve Stem Outside Diameter, in (mm) ............... 0.3110-0.3115 (7.8994-7.9121)
Exhaust Valve Stem Outside Diameter, in (mm) ............... 0.3100-0.3105 (7.8740-7.8867)
Valve Guide Inside Diameter, in (mm) ............... 0.3130-0.3140 (7.9502-7.9756)
Valve Guide Overall Length, in (mm) ............... 2.125 (53.975)
Intake Valve Stem-to-Guide Clearance, in (mm) ............... 0.0015-0.0030 (0.0381-0.0762)
Exhaust Valve Stem-to-Guide Clearance in (mm) ............... 0.0025-0.0040 (0.0635-0.1016)
Valve Seat Angle ............... 45 deg
Valve Face Angle ............... 44.5 deg
Valve Seat Contact Width, in (mm) ............... 0.045-0.060 (1.143-1.524)
Valve Spring Free Length, in (mm) ............... 1.437 (36.499)
Camshaft Overall Assembly Length, in (mm) ............... 4.875 (123.825)
Camshaft Journal Outside Diameter, in (mm) ............... 0.625 (15.875)
Camshaft Bearing Outside Diameter, in (mm) ............... 0.6235-0.6240 (15.8369-15.8496)
Camshaft Bearing Clearance, in (mm) ............... 0.0010-0.0025 (0.0254-0.0635)
Camshaft End Play, in (mm) ............... 0.002-0.006 (0.050-0.152)

Tightening Torques

Cylinder Head Bolts, lb-ft (Nm) ............... 14.0-18.0 (19.0-24.4)
Connecting Rod Cap Bolts, lb-ft (Nm) ............... 9.0-11.0 (12.2-14.9)
Spark Plug Core, lb-ft (Nm) ............... 25.0-30.0 (33.9-40.7)
Flywheel Core Shaft Nut, lb-ft (Nm) ............... 50.0-60.0 (67.8-81.4)
Crankcase Gear Cover Plate Screws, lb-ft (Nm) ............... 8.0-10.0 (10.8-13.5)
Crankcase Base Cover Bolts, lb-ft (Nm) ............... 8.0-10.0 (10.8-13.5)
Magneto Housing Base Flange Fasteners, lb-ft (Nm) ............... 12.0-14.0 (16.3-19.0)
Valve Inspection Chamber Cap Nut, lb-ft (Nm) ............... 4.0-6.0 (5.4-8.1)
Carburetor Mounting Flange Nuts, lb-ft (Nm) ............... 8.0-10.0 (10.8-13.5)
Intake Exhaust Manifold Block Studs, lb-ft (Nm) ............... 10.0-12.0 (13.5-16.3)
Governor Lever Clamp Bolt Adjusting Nut, lb-ft (Nm) ............... 5.0-7.0 (6.8-9.5)
Oil Drain Plug, lb-ft (Nm) ............... 15.0-20.0 (20.3-27.1)
Oil Filler Hole Core Plug, lb-ft (Nm) ............... 12.0-15.0 (16.3-20.3)
Breather Body Valve Plate Screw, lb-ft (Nm) ............... 3.0-5.0 (4.1-6.8)
Air Shroud Housing Attachment Screws, lb-ft (Nm) ............... 4.0-6.0 (5.4-8.1)
Flywheel Starter Pulley Mount Screws, lb-ft (Nm) ............... 8.0-10.0 (10.8-13.5)
Camshaft Thrust Pin Plate Fasteners, lb-ft (Nm) ............... 5.0-7.0 (6.8-9.5)
Fuel Tank Supporting Bracket Fasteners, lb-ft (Nm) ............... 10.0-12.0 (13.5-16.3)
Fuel Strainer Sediment Bowl Ring Nut, lb-ft (Nm) ............... 2.0-3.0 (2.7-4.1)
Air Cleaner Support Mounting Nuts, lb-ft (Nm) ............... 8.0-10.0 (10.8-13.5)
Reduction Gear Unit Outer Case Bolts, lb-ft (Nm) ............... 14.0-18.0 (19.0-24.4)
Reduction Gear Drive Flange Lock Screw, lb-ft (Nm) ............... 22.0-26.0 (29.8-35.2)
Clutch Housing Assembly Mounting Bolts, lb-ft (Nm) ............... 24.0-28.0 (32.5-38.0)
Magneto Rotor Core Shaft Locking Nut, lb-ft (Nm) ............... 4.0-6.0 (5.4-8.1)
Governor Weight Carrier Assembly Screw, lb-ft (Nm) ............... 6.0-8.0 (8.1-10.8)
Crankcase Ventilation Sheet Baffle Screws, lb-ft (Nm) ............... 3.0-4.0 (4.1-5.4)
Exhaust Elbow Pipe Coupler Extension, lb-ft (Nm) ............... 25.0-35.0 (33.9-47.4)
Muffler Core Body Assembly Connection, lb-ft (Nm) ............... 15.0-25.0 (20.3-33.9)
Fuel Diaphragm Pump Body Valve Screws, lb-ft (Nm) ............... 2.5-3.5 (3.4-4.7)
Spark Plug Terminal Nut, lb-ft (Nm) ............... 1.0-1.5 (1.4-2.0)

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• Wisconsin Engines Specs
  
• Wisconsin AB Specs
  
• Wisconsin ACN Specs
  
• Wisconsin AEH Specs
  
• Wisconsin AHH Specs
  

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