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Wisconsin AEH Engine

The Wisconsin AEH is a vintage, heavy-duty, single-cylinder Wisconsin Motors air-cooled industrial engine manufactured primarily during the 1940s. Built with rugged cast-iron construction, this four-cycle engine was engineered for demanding commercial, agricultural, and industrial applications (powering equipment like the classic Gibson Model A and D tractors). It is widely recognized for its high-torque durability, reliable mechanical design, and long operational lifespan. The engine employs a side-valve (L-head) design layout, with both the intake and exhaust valves running parallel to the cylinder bore inside the main engine block. Bore: 3.00 inches (76 mm). Stroke: 3.25 inches (83 mm). Total Displacement: 23 cubic inches (approx. 0.4 Liters).

The fuel system delivers a proper combustible fuel-air mixture utilizing a gravity-fed setup paired with a side-draft Stromberg or Zenith carburetor. Combustion air is filtered through an integrated heavy-duty oil bath air cleaner before entering the intake tract. Engine speed and throttle regulation are controlled mechanically by an external, adjustable centrifugal flyball governor assembly. This governor automatically monitors load changes and adjusts the carburetor throttle shaft to stabilize target operating RPM. Fuel delivery relies on a machine-mounted fuel tank available in factory options of 1.35 or 2.75-gallon capacities.

Lubrication is managed using a internal splash-type system driven by a positive-displacement plunger/piston-type oil pump. The oil pump acts directly to supply and maintain a consistent oil level in an open connecting rod trough located within the lower crankcase oil pan. Maintenance procedures require regular oil changes and clearing accumulated sludge from the internal oil pan and inspection covers to prevent the internal pump check balls from sticking to their seats. Factory spec recommendations call for straight-weight SAE 30 oil under standard temperature ranges, adapting from SAE 10W up to SAE 40 depending on ambient operational climates.

The unit is entirely air-cooled via a forced-air design. A combination fan-flywheel serves as the primary blower unit. This fan assembly is fully enclosed inside a heavy sheet-metal shroud. The shroud works in tandem with localized metal air ducts and internal cylinder baffle plates to evenly channel and distribute high-velocity airflow directly over the external cooling fins of the cast-iron cylinder block and cylinder head.

General Technical Data

Engine Specifications

Engine Model ............... Wisconsin AEH
Engine Type ............... 4-cycle single-cylinder air-cooled heavy-duty industrial gasoline
Number of Cylinders ............... 1
Cylinder Arrangement ............... Vertical upright single-cylinder config
Engine Bore, in (mm) ............... 3.00 (76.20)
Engine Stroke, in (mm) ............... 3.25 (82.55)
Displacement, cu.in (cc) ............... 23.0 (377.0)
Rated Power at 1600 rpm, hp (kW) ............... 4.1 (3.05)
Rated Power at 1800 rpm, hp (kW) ............... 4.8 (3.58)
Rated Power at 2000 rpm, hp (kW) ............... 5.4 (4.02)
Rated Power at 2200 rpm, hp (kW) ............... 5.9 (4.4)
Maximum Power at Peak Speed, hp (kW) ............... 6.1 (4.5)
Maximum Governed Speed, rpm ............... 2200
Maximum Idle Speed, rpm ............... 2400
Minimum Low Idle Speed, rpm ............... 1000
Peak Torque at 2200 rpm, lb-ft (Nm) ............... 14.2 (19.2)
Peak Torque at 1600 rpm, lb-ft (Nm) ............... 14.9 (20.2)
Compression Ratio ............... 5.10:1
Crankshaft Rotation Direction ............... Clockwise when viewing from flywheel side
Cylinder Block Material ............... Close-grained cast iron alloy
Cylinder Head Material ............... Close-grained cast iron alloy with deep cooling fins
Crankcase Housing Material ............... Cast iron integrated base reservoir
Piston Assembly Material ............... Light-weight aluminum alloy or selectable cast iron
Connecting Rod Assembly ............... Drop-forged steel with split babbitt bearing journal
Main Bearings Configuration ............... Heavy-duty tapered roller bearings on flywheel side
Valve Mechanism Arrangement ............... Side valve L-head design configuration
Camshaft Construction ............... Drop-forged steel with hardened cam profiles and gears
Cooling Method ............... Forced air via flywheel fan blower shroud assembly
Lubrication Method ............... Splash feed with individual plunger pump mechanism
Filtration System ............... Oil bath type or optional heavy duty dry cartridge system
Ignition System ............... High tension magneto with automatic impulse starter coupling
Starting System ............... Manual rope wrap pulley or integrated hand crank starter handle
Electrical System ............... Optional 6V belt-driven starter generator assembly

Fuel System

Carburetor Model (Std) ............... Zenith Model 61 Series cast iron configuration
Carburetor Model (Opt) ............... Stromberg small-bore updraft industrial configuration
Carburetor Intake Throat Diameter, in (mm) ............... 1.06 (26.97)
Fuel Delivery Method ............... Gravity feed from elevated chassis tank reservoir to float chamber
Optional Fuel Delivery Method ............... Mechanical diaphragm fuel pump driven by camshaft lobe
Fuel Strainer Component ............... Sediment bowl screen assembly with thumb screw shutoff valve
Main Jet Config ............... Adjustable needle valve arrangement for variable high speed control
Idle Jet Config ............... Adjustable needle valve arrangement for low speed mixture correction
Choke Valve Control ............... Manual lever with positive lock detent
Governor Configuration ............... Mechanical centrifugal flyball type
Fuel Tank Capacity Option Standard, gal (L) ............... 1.35 (5.11)
Fuel Tank Capacity Option Extended, gal (L) ............... 2.75 (10.41)
Recommended Fuel Grade ............... Clean regular unleaded automotive grade gasoline
Alternative Fuel Capacity Configuration ............... Kerosene or liquefied petroleum gas
Carburetor Float Level Setting, in (mm) ............... 1.16 (29.36)
Venturi Tube Diameter, in (mm) ............... 0.75 (19.05)
Fuel Tank Construction Material ............... Heavy-gauge terneplate steel with soldered joints
Air Cleaner Connection Type ............... Cast aluminum air intake elbow with clamping screw

Dimensions and Weight

Overall Height, in (mm) ............... 24.0 (610)
Overall Width, in (mm) ............... 18.5 (470)
Overall Depth, in (mm) ............... 19.2 (490)
Dry Weight (Standard Base), lbs (kg) ............... 130 (59)
Dry Weight with Gear Reduction Box, lbs (kg) ............... 155 (70)

Maintenance Data

Service Information

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)
Ignition Spark Angle, deg ............... 20.0
Intake Valve Clearance (Cold), in (mm) ............... 0.0080 (0.203)
Exhaust Valve Clearance (Cold), in (mm) ............... 0.0160 (0.406)

Engine Oil

Engine Oil Type .................. SAE 30, SAE 20W, or SAE 10W
API Service Classifications ......................... SE, SF, SG, or CC
Crankcase Oil Reservoir Capacity, qt (L) ............... 2.25 (2.13)
Air Cleaner Oil Capacity, pt (L) ............... 0.50 (0.24)
Reduction Gearbox Oil Reservoir Capacity, pt (L) ............... 1.0 (0.47)

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) ............... 3.0000-3.0005 (76.200-76.213)
Cylinder Bore Maximum Out of Round, in (mm) ............... 0.0030 (0.076)
Cylinder Bore Maximum Taper, in (mm) ............... 0.0040 (0.102)
Crankshaft Main Journal Diameter, in (mm) ............... 1.6250-1.6255 (41.275-41.288)
Crankpin Journal Diameter, in (mm) ............... 1.6250-1.6255 (41.275-41.288)
Crankshaft End Play, in (mm) ............... 0.0040-0.0060 (0.102-0.152)
Connecting Rod Length Center to Center, in (mm) ............... 6.500 (165.100)
Connecting Rod Journal Bore I.D, in (mm) ............... 1.6265-1.6270 (41.313-41.326)
Connecting Rod Radial Clearance, in (mm) ............... 0.0010-0.0020 (0.025-0.051)
Connecting Rod Side Clearance, in (mm) ............... 0.0050-0.0100 (0.127-0.254)
Connecting Rod Small End Bushing I.D, in (mm) ............... 0.7508-0.7512 (19.070-19.080)
Piston to Cylinder Clearance, in (mm) ............... 0.0035-0.0040 (0.089-0.102)
Piston Pin Bore Inside Diameter, in (mm) ............... 0.7501-0.7503 (19.053-19.058)
Piston Pin Outer Diameter, in (mm) ............... 0.7500-0.7503 (19.050-19.058)
Piston Pin to Piston Pin Bore Clearance, in (mm) ............... 0.0001-0.0004 (0.003-0.010)
Piston Pin to Con Rod Bushing Clearance, in (mm) ............... 0.0005-0.0009 (0.013-0.023)
Top Ring Groove Width, in (mm) ............... 0.1240-0.1250 (3.150-3.175)
Second Ring Groove Width, in (mm) ............... 0.1240-0.1250 (3.150-3.175)
Third Ring Groove Width, in (mm) ............... 0.1240-0.1250 (3.150-3.175)
Oil Ring Groove Width, in (mm) ............... 0.1865-0.1875 (4.737-4.763)
Top Ring Groove Side Clearance, in (mm) ............... 0.0020-0.0035 (0.051-0.089)
Second Ring Groove Side Clearance, in (mm) ............... 0.0015-0.0030 (0.038-0.076)
Third Ring Groove Side Clearance, in (mm) ............... 0.0015-0.0030 (0.038-0.076)
Oil Ring Groove Side Clearance, in (mm) ............... 0.0015-0.0030 (0.038-0.076)
Piston Ring End Gap, in (mm) ............... 0.0070-0.0120 (0.178-0.305)
Cylinder Head Deck Flatness Surface Distortion, in (mm) ............... 0.0030 (0.076)
Cylinder Block Deck Flatness Surface Distortion, in (mm) ............... 0.0030 (0.076)
Intake Valve Head Diameter, in (mm) ............... 1.375 (34.925)
Exhaust Valve Head Diameter, in (mm) ............... 1.250 (31.750)
Intake Valve Stem Outer Diameter, in (mm) ............... 0.3110-0.3115 (7.900-7.912)
Exhaust Valve Stem Outer Diameter, in (mm) ............... 0.3105-0.3110 (7.887-7.900)
Intake Valve Stem to Guide Clearance, in (mm) ............... 0.0020-0.0035 (0.051-0.089)
Exhaust Valve Stem to Guide Clearance, in (mm) ............... 0.0035-0.0050 (0.089-0.127)
Valve Guide Inside Diameter, in (mm) ............... 0.3135-0.3140 (7.963-7.976)
Valve Stem Guide Total Length, in (mm) ............... 2.250 (57.150)
Valve Spring Free Length, in (mm) ............... 2.125 (53.975)
Valve Seat Angle, deg ............... 45.000
Valve Face Angle, deg ............... 45.000
Valve Seat Contact Width, in (mm) ............... 0.0625-0.0937 (1.587-2.381)
Valve Head Margin Thickness, in (mm) ............... 0.0312 (0.793)
Camshaft Main Journal Diameter (Flywheel), in (mm) ............... 1.1250-1.1255 (28.575-28.588)
Camshaft Main Journal Diameter (PTO), in (mm) ............... 1.1250-1.1255 (28.575-28.588)
Camshaft Journal Oil Clearance, in (mm) ............... 0.0015-0.0030 (0.038-0.076)
Cam Lobe Height (Intake), in (mm) ............... 1.5000-1.5020 (38.100-38.151)
Cam Lobe Height (Exhaust), in (mm) ............... 1.5000-1.5020 (38.100-38.151)

Tightening Torques

Cylinder Head Bolt (3/8-16), lb-ft (Nm) ............... 28.0-32.0 (37.9-43.4)
Cylinder Head Stud Nut (3/8-24), lb-ft (Nm) ............... 32.0-36.0 (43.4-48.8)
Connecting Rod Cap Bolt, lb-ft (Nm) ............... 22.0-25.0 (29.8-33.9)
Main Bearing Housing Cap Screw, lb-ft (Nm) ............... 24.0-26.0 (32.5-35.3)
Flywheel Lock Nut, lb-ft (Nm) ............... 90.0-100.0 (122.0-135.6)
Oil Pan Base Mounting Bolt, lb-ft (Nm) ............... 14.0-18.0 (19.0-24.4)
Magneto Mounting Base Cap Screw, lb-ft (Nm) ............... 20.0-24.0 (27.1-32.5)
Spark Plug Core, lb-ft (Nm) ............... 25.0-30.0 (33.9-40.7)
Intake and Exhaust Manifold Nut, lb-ft (Nm) ............... 12.0-16.0 (16.2-21.7)
Valve Inspection Cover Center Nut, lb-ft (Nm) ............... 8.0-10.0 (10.8-13.6)
Air Shroud Panel Sheet Metal Screw, lb-ft (Nm) ............... 5.0-7.0 (6.8-9.5)
Governor Lever Clamp Bolt, lb-ft (Nm) ............... 6.0-8.0 (8.1-10.8)
Carburetor Mounting Flange Stud Nut, lb-ft (Nm) ............... 12.0-15.0 (16.3-20.3)
Oil Pump Trough Screw, lb-ft (Nm) ............... 6.0-8.0 (8.1-10.8)
Oil Pump Body Base Core Screw, lb-ft (Nm) ............... 14.0-16.0 (19.0-21.7)
Fuel Tank Mounting Bracket Bolt, lb-ft (Nm) ............... 14.0-18.0 (19.0-24.4)
Fuel Tank Strap Clamping Nut, lb-ft (Nm) ............... 4.0-6.0 (5.4-8.1)
Air Cleaner Bracket Mounting Bolt, lb-ft (Nm) ............... 12.0-15.0 (16.3-20.3)
Breather Assembly Cap Screw, lb-ft (Nm) ............... 5.0-7.0 (6.8-9.5)
Camshaft Gear Retaining Bolt, lb-ft (Nm) ............... 14.0-18.0 (19.0-24.4)
Crankshaft Gear Key Alignment Setscrew, lb-ft (Nm) ............... 8.0-10.0 (10.8-13.6)
Flywheel Blower Fan Ring Fastener, lb-ft (Nm) ............... 22.0-26.0 (29.8-35.3)
Gear Reduction Case Cover Fastener, lb-ft (Nm) ............... 24.0-28.0 (32.5-38.0)
Gear Reduction Case Housing Base Bolt, lb-ft (Nm) ............... 26.0-30.0 (35.2-40.7)
Hand Crank Support Casting Face Screw, lb-ft (Nm) ............... 22.0-26.0 (29.8-35.2)
Magneto Drive Gear Retaining Jam Nut, lb-ft (Nm) ............... 30.0-35.0 (40.7-47.4)
Governor Flyweight Carrier Nut, lb-ft (Nm) ............... 40.0-45.0 (54.2-61.0)
Crankcase Side Inspection Plate Cap Screw, lb-ft (Nm) ............... 12.0-15.0 (16.3-20.3)
Fuel Diaphragm Pump Actuator Arm Screw, lb-ft (Nm) ............... 5.0-7.0 (6.8-9.5)

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• Wisconsin Engines Specs
  
• Wisconsin AB Specs
  
• Wisconsin ABN Specs
  
• Wisconsin ACN Specs
  
• Wisconsin AHH Specs
  

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