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Wisconsin AENL Engine

The Wisconsin AENL is a heavy-duty, single-cylinder, four-cycle, air-cooled gasoline engine manufactured by the Wisconsin Motor Corporation. Engineered primarily for demanding agricultural and industrial machinery, this model serves as a direct, upgraded replacement for the obsolete AEN and AENS lines.
The engine block is a rugged, cast-iron design featuring a substantial increase in cooling fin surface area compared to its predecessors to promote thermal stability during extended continuous-duty operations. A heavy mechanical footprint and exceptionally high low-end torque characteristics make it highly reliable for severe-duty applications, such as log splitters, vintage tractors, and industrial pumps. Serviceability remains robust due to standard modular components, including externally adjustable magneto systems and adjustable governor control links.

The powerhead utilizes an L-head (side-valve) valve-in-block design. Standard AENL models feature a hardened exhaust valve and matching heavy-duty seat insert. On specialized variants (such as the AENLD), the assembly incorporates an integrated mechanical valve rotator on the exhaust side to prevent valve sticking and ensure uniform heat distribution under high-load states. Internal dimensions feature a standard cylinder bore of 3.00 inches and a piston stroke of 3.25 inches. Total engine displacement measures exactly 23.0 cubic inches (377 cc).

Fuel System: The fuel management architecture comprises a gravity-feed or low-pressure mechanical system feeding into a balanced, single-barrel carburetor (commonly a Zenith or alternate factory configuration). The assembly provides automated, correct fuel-to-air mixing ratios across all fluctuating load ranges. Engine speed control is managed via a built-in centrifugal flyball-type governor, which automatically modulates the carburetor throttle shaft opening based on the mechanical load applied to the power take-off shaft.

Engine components rely entirely on a self-contained splash lubrication system driven by the internal rotation of the crankshaft assemblies. The engine oil sump requires no auxiliary oil pump. Thermal regulation uses a high-velocity forced air-cooling system. Air circulation is generated by a combination fan-flywheel assembly encased within a fitted sheet metal shroud. Internal air flow is split and directed across the cylinder block and head fins using specialized ducting and internal baffle plates to guarantee a uniform engine temperature profile.

General Technical Data

Engine Specifications

Engine Model ............... Wisconsin AENL
Engine Type ............... 4-cycle single-cylinder air-cooled heavy-duty internal combustion gasoline
Number of Cylinders ............... 1
Cylinder Arrangement ............... Vertical
Engine Bore, in (mm) ............... 3.00 (76.2)
Engine Stroke, in (mm) ............... 3.25 (82.6)
Displacement, cu.in (cc) ............... 23.0 (377)
Rated Engine Power, hp (kW) ............... 4.7-9.2 (3.5-6.9)
Rated Engine Speed, rpm ............... 1600-3600
Peak Torque ............... 16.0 lb-ft (21.7 Nm) at 2200 rpm
Idle Speed ............... 1000-1200 rpm
Operating Speed ............... 1600-3600 rpm
Compression Ratio ............... 5.1:1-5.5:1
Cylinder Block Type ............... Cast iron split-crankcase
Cylinder Head Type ............... Cast iron removable dynamic-fin
Lubrication System ............... Full splash constant-level ejector-pump
Oil Pump Type ............... Plunger-driven splash-nozzle mechanism
Oil Filter Type ............... Optional bypass external-cartridge
Cooling System ............... Air-cooled forced-induction flywheel-blower
Air Cleaner Type ............... Oil-bath or dry element element-type
Starting System ............... Rope starter or electric starter-generator
Electrical System ............... 12V negative-ground circuit option

Fuel System

Carburetor Manufacturer ............... Zenith or Marvel-Schebler
Carburetor Type ............... Updraft internal venturi side-draft optional
Fuel Type ............... Regular gasoline 74-90 octane minimum
Fuel Tank Capacity, gal (L) ............... 1.70 (6.44)
Fuel Delivery Type ............... Gravity-feed or mechanical camshaft-diaphragm pump
Fuel Filter Type ............... Sediment bowl glass-assembly with screen mesh
Choke Type ............... Manual cable-operated butterfly valve
Governor Type ............... Centrifugal flyweight mechanical flyball-type
Governor Regulation ............... Close mechanical tracking within 3-5 percent limits
Main Jet Specification ............... Fixed orifice standard metering or adjustable needle
Idle Adjustment Jet ............... Low-speed needle variable needle circuit air-bleed
Fuel Line Material ............... Copper-tubing or steel-reinforced flexible hose
Fuel Pump Operating Pressure, psi (kPa) ............... 1.5-3.0 (10.3-20.7)
Alternative Fuel Config ............... Liquid petroleum gas or natural gas modification kits
Carburetor Mounting Flange Bolt Center, in (mm) ............... 2.00 (50.8)
Carburetor Throttle Bore Diameter, in (mm) ............... 1.00 (25.4)
Air Intake Connection Diameter, in (mm) ............... 1.25 (31.8)
Float Setting Level, in (mm) ............... 1.29 (32.8)
Float Needle Seat Diameter, in (mm) ............... 0.06 (1.5)
Venturi Internal Diameter, in (mm) ............... 0.75 (19.1)
Idle Needle Setting Range ............... 1.00-1.50 open turns from seat seat-base
Main Needle Adjusting Range ............... 1.25-2.00 open turns from seating seat-base
Fuel Tank Shut-Off Mechanism ............... Manual petcock needle-valve integrated sediment assembly

Dimensions and Weight

Engine Height, in (mm) ............... 21.3 (540)
Engine Width, in (mm) ............... 18.5 (470)
Engine Length, in (mm) ............... 15.8 (400)
Net Weight, lbs (kg) ............... 110 (50)

Maintenance Data

Service Information

Engine Compression Rating, psi (kPa) ............... 90-110 (620-758)
Minimum Operating Compression, psi (kPa) ............... 75 (517)
Spark Plug Type ............... Champion D16 or equivalent
Spark Plug Gap, in (mm) ............... 0.030 (0.76)
Breaker Point Gap, in (mm) ............... 0.015 (0.38)
Distributor Breaker Gap, in (mm) ............... 0.020 (0.51)
Ignition Timing Setting, deg ............... 20.0 BTDC
Starter-Generator Belt Deflection Tension, in (mm) ............... 0.50 (12.7)
Intake Valve Clearance (Cold), in (mm) ............... 0.008 (0.20)
Exhaust Valve Clearance (Cold), in (mm) ............... 0.016 (0.41)

Engine Oil

Engine Oil Type .................. SAE 30, SAE 20W, or SAE 10W
API Service Classifications ......................... SE, SF, SG, or CC
Crankcase Oil Capacity, pt (L) ............... 2.50 (1.18)
Air Cleaner Oil Capacity, pt (L) ............... 0.50 (0.24)
Reduction Gear Oil 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 50 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 Out-of-Round Maximum, in (mm) ............... 0.0010 (0.025)
Crankshaft Main Journal O.D, in (mm) ............... 2.0000-2.0005 (50.800-50.813)
Crankpin Journal Standard O.D, in (mm) ............... 1.6250-1.6255 (41.275-41.288)
Crankshaft End Play, in (mm) ............... 0.0020-0.0040 (0.051-0.102)
Connecting Rod Oil Clearance, in (mm) ............... 0.0007-0.0022 (0.018-0.056)
Connecting Rod Side Play, in (mm) ............... 0.0040-0.0080 (0.102-0.203)
Connecting Rod Small End Bushing Wear Limit, in (mm) ............... 0.0015 (0.038)
Piston to Cylinder Wall Clearance, in (mm) ............... 0.0035-0.0045 (0.089-0.114)
Piston Pin Outer Diameter, in (mm) ............... 0.7500-0.7503 (19.050-19.058)
Piston Pin to Piston Pin Bore Clearance, in (mm) ............... 0.0001-0.0005 (0.003-0.013)
Piston Pin to Con Rod Bushing Small End, in (mm) ............... 0.0004-0.0009 (0.010-0.023)
Top Ring Groove Width, in (mm) ............... 0.0950-0.0960 (2.413-2.438)
Second Ring Groove Width, in (mm) ............... 0.0950-0.0960 (2.413-2.438)
Third Ring Groove Width, in (mm) ............... 0.0950-0.0960 (2.413-2.438)
Oil Ring Groove Width, in (mm) ............... 0.1885-0.1895 (4.788-4.813)
Piston Ring Groove Side Clearance, in (mm) ............... 0.0015-0.0035 (0.038-0.089)
Piston Ring End Gap in (mm) ............... 0.0070-0.0170 (0.178-0.432)
Valve Guide Inside Diameter, in (mm) ............... 0.3125-0.3135 (7.938-7.963)
Intake Valve Stem to Guide Clearance, in (mm) ............... 0.0015-0.0030 (0.038-0.076)
Exhaust Valve Stem to Guide Clearance, in (mm) ............... 0.0030-0.0045 (0.076-0.114)
Valve Seat Angle, deg ............... 45.0
Valve Face Angle, deg ............... 45.0
Valve Margin Thickness, in (mm) ............... 0.0312 (0.792)
Valve Spring Free Length, in (mm) ............... 1.7500 (44.450)
Valve Lifter Tappet Diameter, in (mm) ............... 0.5000-0.5005 (12.700-12.713)
Valve Lifter Guide Bore Diameter, in (mm) ............... 0.5015-0.5025 (12.738-12.764)
Valve Lifter to Bore Clearance, in (mm) ............... 0.0010-0.0025 (0.025-0.064)
Camshaft Journal Diameter (Front), in (mm) ............... 1.3750-1.3755 (34.925-34.938)
Camshaft Journal Diameter (Rear), in (mm) ............... 1.1250-1.1255 (28.575-28.588)
Camshaft Bearing Clearance, in (mm) ............... 0.0015-0.0035 (0.038-0.089)
Camshaft End Play, in (mm) ............... 0.0020-0.0060 (0.051-0.152)

Tightening Torques

Cylinder Head Nuts, lb-ft (Nm) ............... 22-24 (29.8-32.5)
Connecting Rod Cap Bolts, lb-ft (Nm) ............... 22-26 (29.8-35.3)
Flywheel Shaft Locking Nut, lb-ft (Nm) ............... 90-100 (122.0-135.6)
Main Bearing Casing Plate Capscrews, lb-ft (Nm) ............... 25-30 (33.9-40.7)
Crankcase Split Frame Bolts, lb-ft (Nm) ............... 22-26 (29.8-35.3)
Spark Plug Core, lb-ft (Nm) ............... 25-30 (33.9-40.7)
Crankcase Inspection Plate Fasteners, lb-ft (Nm) ............... 10-14 (13.6-19.0)
Oil Drain Plug Core, lb-ft (Nm) ............... 20-25 (27.1-33.9)
Magneto Attachment Mount Screws, lb-ft (Nm) ............... 16-20 (21.7-27.1)
Governor Assembly Flange Bracket Nuts, lb-ft (Nm) ............... 8-12 (10.8-16.3)
Air Cleaner Mounting Flange Capscrews, lb-ft (Nm) ............... 8-12 (10.8-16.3)
Carburetor Mounting Flange Inverted Nuts, lb-ft (Nm) ............... 12-16 (16.3-21.7)
Fuel Pump Mechanical Mounting Screws, lb-ft (Nm) ............... 12-16 (16.3-21.7)
Blower Shroud Shield Fastening, lb-ft (Nm) ............... 6-10 (8.1-13.6)
Cylinder Shroud Deflector Tin Plate Bolts, lb-ft (Nm) ............... 6-10 (8.1-13.6)
Exhaust Manifold Assembly Flange Nuts, lb-ft (Nm) ............... 15-20 (20.3-27.1)
Intake Manifold Block Port Flange Screws, lb-ft (Nm) ............... 15-20 (20.3-27.1)
Camshaft Thrust Washer Anchor Plate Bolts, lb-ft (Nm) ............... 8-12 (10.8-16.3)
Oil Pump Plunger Bracket Attachment Screws, lb-ft (Nm) ............... 6-10 (8.1-13.6)
Breather Assembly Valve Cover Plate Fasteners, lb-ft (Nm) ............... 4-7 (5.4-9.5)
Flywheel Alternator Stator Core Mounting Screws, lb-ft (Nm) ............... 5-8 (6.8-10.8)
Starter-Generator Pivot Base Bracket Bolts, lb-ft (Nm) ............... 25-30 (33.9-40.7)
Starter-Generator Adjusting Link Locking Bolt, lb-ft (Nm) ............... 15-20 (20.3-27.1)
Crankshaft Front Timing Gear Nut Lock, lb-ft (Nm) ............... 50-60 (67.8-81.3)
Valve Inspection Cover Spring Center Stud, lb-ft (Nm) ............... 4-6 (5.4-8.1)
Fuel Tank Support Mounting Holding Bracket Nuts, lb-ft (Nm) ............... 10-14 (13.6-19.0)
Governor Lever Arm Pinch Bolt, lb-ft (Nm) ............... 7-10 (9.5-13.6)
Sediment Bowl Bracket Clamping Ring Fastener, lb-in (Nm) ............... 15-25 (1.7-2.8)
Air Baffle Lower Shroud Bracket Bolts, lb-ft (Nm) ............... 6-10 (8.1-13.6)
Oil Sump Drain Extension Pipe Union, lb-ft (Nm) ............... 25-30 (33.9-40.7)
Flywheel Fan Shroud Screen Small Screws, lb-in (Nm) ............... 20-30 (2.3-3.4)
Magneto Cover Shell Terminal Insulation Nut, lb-in (Nm) ............... 10-15 (1.1-1.7)
Breaker Point Locking Terminal Screw, lb-in (Nm) ............... 5-8 (0.6-0.9)
Distributor Housing Clamp Screw, lb-ft (Nm) ............... 12-15 (16.3-20.3)
Clutch Take-Off Housing Mounting Capscrews, lb-ft (Nm) ............... 22-26 (29.8-35.3)
Reduction Gear Unit Outer Case Joint Screws, lb-ft (Nm) ............... 18-22 (24.4-29.8)
PTO Shaft Output End Collar Set Screws, lb-ft (Nm) ............... 10-14 (13.6-19.0)
Air Cleaner Support Iron Bar Holding Fasteners, lb-ft (Nm) ............... 14-18 (19.0-24.4)
Governor Flyweight Assembly Shaft Retainer, lb-in (Nm) ............... 30-40 (3.4-4.5)
Oil Sump Base To Block Mounting Fasteners, lb-ft (Nm) ............... 22-26 (29.8-35.3)
Cylinder Block To Crankcase Alignment Bolts, lb-ft (Nm) ............... 35-40 (47.5-54.2)

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• Wisconsin Engines Specs
  
• Wisconsin AEN Specs
  
• Wisconsin AENLD Specs
  
• Wisconsin AGND Specs
  
• Wisconsin AKN Specs
  
• Wisconsin AKS Specs
  
• Wisconsin BKN Specs
  

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