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Wisconsin ACN Engine

The Wisconsin Model ACN is a heavy-duty, single-cylinder, four-cycle, air-cooled industrial engine. Manufactured by the Wisconsin Motor Corporation, this internal combustion engine is engineered for demanding field service across agricultural, construction, and industrial applications. It features a robust cast-iron block and crankcase assembly designed to provide high structural integrity and exceptional reliability during extended periods of continuous operation.

Valve Configuration: Side-valve (L-head / flathead) layout, with the intake and exhaust valves located within the cylinder block. The standard ACN engine utilizes heat-resistant alloy steel valves. High-specification variants designated as the Models ACND are equipped with premium Stellite exhaust valves and valve seat inserts to withstand higher thermal loads. Internal cylinder bore diameter is 2-5/8 inches (2.62") and the piston stroke length is 2-3/4 inches (2.75"). This configuration yields a total engine displacement of 14.9 cubic inches.

Lubrication System: Operating on a constant-level splash lubrication architecture. A positive-displacement, mechanical plunger-type oil pump draws oil from the lower oil pan and continually supplies a localized oil trough located directly under the connecting rod cap. The connecting rod dipper strikes this oil pool, generating a continuous mist that coats the cylinder walls, camshaft, and internal bearings.

Fuel System: Gravity-fed fuel delivery network supplying a balanced, float-feed carburetor. Fuel travels from the top-mounted fuel tank, through a manual fuel shut-off valve and sediment bowl, into the carburetor bowl. The carburetor automatically regulates fuel-to-air ratios across changing load and speed demands, while an internal centrifugal flyweight governor stabilizes engine speed under fluctuating operating conditions.

Cooling System: Forced air-cooling managed by a combination fan-flywheel assembly. The flywheel features integrated fan blades that pull outside air in and force it through a structured sheet-metal air shroud encasing the engine block. Internal baffles and ducts uniformly distribute this air stream across the cooling fins of both the cylinder block and cylinder head.

General Technical Data

Engine Specifications

Engine Model ............... Wisconsin ACN
Engine Type ............... 4-cycle single-cylinder L-head heavy-duty air-cooled gasoline
Number of Cylinders ............... 1
Cylinder Arrangement ............... Vertical single-cylinder
Engine Bore, in (mm) ............... 2.625 (66.68)
Engine Stroke, in (mm) ............... 2.75 (69.85)
Displacement, cu.in (L) ............... 14.88 (0.244)
Rated Engine Power, hp (kW) ............... 2.3-6.0 (1.7-4.5)
Rated Engine Speed, rpm ............... 1600-3600
Peak Torque ............... 9.4 lb-ft (12.7 Nm) at 2200 rpm
Idle Speed ............... 1000-1200 rpm
Maximum No Load Speed ............... 3800 rpm
Operating Speed ............... 1600-3600 rpm
Compression Ratio ............... 5.1:1-5.3:1
Cylinder Block Type ............... Cast iron
Cylinder Head Type ............... Cast iron aluminum alloy option
Lubrication System ............... Splash lubrication with oil pump mechanism
Oil Pump Type ............... Plunger-driven pump
Oil Filter Type ............... Optional bypass or element strainer
Cooling System ............... Air-cooled by flywheel fan shroud assembly
Air Cleaner Type ............... Oil bath or dry element type
Starting System ............... Rope start or recoil option or electric starter
Electrical System ............... Magneto ignition or 12V flywheel alternator option

Fuel System

Carburetor Manufacturer ............... Zenith or Walbro
Carburetor Type ............... Side draft or updraft float feed type
Fuel Feed Method ............... Gravity feed or mechanical fuel pump
Fuel Pump Type ............... Camshaft driven diaphragm type
Fuel Strainer Type ............... Sediment bowl with fine mesh screen
Fuel Type ............... Regular grade automotive gasoline
Minimum Octane Rating ............... 80-90 AKI
Fuel Tank Capacity, gal (L) ............... 1.0 (3.78)
Main Jet Specification ............... Fixed or adjustable needle valve configuration
Idle Jet Adjustment ............... Adjustable air needle type
Choke Type ............... Manual lever with optional remote wire control
Governor Type ............... Mechanical flyweight centrifugal type running in oil bath
Governor Linkage ............... External rod adjustable swivel block setup
Fuel Lines Material ............... Copper or steel tubing flexible composite options
Fuel Shutoff Valve ............... Manual needle petcock at tank outlet base
Float Setting Height, in (mm) ............... 1.53 (39.0)
Venturi Diameter, in (mm) ............... 0.69 (17.5)
Maximum Fuel Pump Pressure, psi (kPa) ............... 2.0-3.5 (13.8-24.1)
Idle Mixture Setting ............... 1.25 turns open from seated seat position
High Speed Needle Setting ............... 1.5 turns open from closed seating position

Dimensions and Weight

Overall Height, in (mm) ............... 18.2 (465)
Overall Width, in (mm) ............... 15.5 (395)
Overall Length, in (mm) ............... 14.1 (360)
Dry Weight, lbs (kg) ............... 76 (34.5)
Shipping Weight, lbs (kg) ............... 85 (38.6)

Maintenance Data

Service Information

Compression Pressure Range, psi (bar) ............... 100-115 (6.9-7.9)
Spark Plug Type ............... Champion D16 or AC C86
Spark Plug Gap, in (mm) ............... 0.030 (0.76)
Breaker Point Gap, in (mm) ............... 0.020 (0.51)
Ignition Timing Angle ............... 23 degrees BTDC
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, qt (L) ............... 1.0 (0.95)
Air Cleaner Oil Bowl Capacity, pt (L) ............... 0.25 (0.12)

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 Standard, in (mm) ............... 2.625-2.626 (66.675-66.700)
Cylinder Bore Out of Round Maximum, in (mm) ............... 0.001 (0.0254)
Cylinder Bore Taper Maximum, in (mm) ............... 0.002 (0.0508)
Connecting Rod Journal Diameter, in (mm) ............... 1.375-1.3755 (34.925-34.938)
Connecting Rod Bearing Clearance, in (mm) ............... 0.0008-0.0022 (0.0203-0.0559)
Connecting Rod Side Clearance, in (mm) ............... 0.004-0.010 (0.102-0.254)
Crankshaft Main Journal Diameter (Flywheel), in (mm) ............... 1.375-1.3755 (34.925-34.938)
Crankshaft Main Journal Diameter (PTO), in (mm) ............... 1.375-1.3755 (34.925-34.938)
Crankshaft Taper and Out of Round, in (mm) ............... 0.0003 (0.0076)
Crankshaft End Play, in (mm) ............... 0.001-0.004 (0.0254-0.1016)
Piston to Cylinder Bore Clearance, in (mm) ............... 0.0035-0.0045 (0.0889-0.1143)
Piston Pin Outside Diameter, in (mm) ............... 0.625-0.6252 (15.875-15.880)
Piston Pin Bushing Clearance, in (mm) ............... 0.0003-0.0008 (0.0076-0.0203)
Piston Pin to Piston Pin Bore Clearance, in (mm) ............... 0.0001-0.0003 (0.0025-0.0076)
Top Ring End Gap, in (mm) ............... 0.007-0.017 (0.178-0.432)
Second Ring End Gap, in (mm) ............... 0.007-0.017 (0.178-0.432)
Third Ring End Gap, in (mm) ............... 0.007-0.017 (0.178-0.432)
Oil Ring End Gap, in (mm) ............... 0.007-0.017 (0.178-0.432)
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)
Intake Valve Stem Outside Diameter, in (mm) ............... 0.3105-0.3115 (7.887-7.912)
Exhaust Valve Stem Outside Diameter, in (mm) ............... 0.3090-0.3100 (7.849-7.874)
Intake Valve Stem to Guide Clearance, in (mm) ............... 0.001-0.003 (0.0254-0.0762)
Exhaust Valve Stem to Guide Clearance, in (mm) ............... 0.0025-0.0045 (0.0635-0.1143)
Valve Guide Inside Diameter, in (mm) ............... 0.3125-0.3135 (7.938-7.963)
Valve Seat Angle ............... 45 degrees
Valve Seat Width, in (mm) ............... 0.045-0.062 (1.143-1.575)
Valve Guide Outer Diameter, in (mm) ............... 0.501-0.502 (12.725-12.738)
Valve Spring Free Length, in (mm) ............... 1.625 (41.28)
Camshaft Journal Diameter (Flywheel), in (mm) ............... 0.625-0.626 (15.875-15.900)
Camshaft Journal Diameter (PTO), in (mm) ............... 0.625-0.626 (15.875-15.900)
Camshaft Bearing Clearance, in (mm) ............... 0.0015-0.0035 (0.0381-0.0889)
Camshaft End Play, in (mm) ............... 0.002-0.006 (0.0508-0.1524)

Tightening Torques

Cylinder Head Screws Bolts, lb-ft (Nm) ............... 22-24 (29.8-32.5)
Connecting Rod Cap Screws Bolts, lb-ft (Nm) ............... 14-16 (19.0-21.7)
Flywheel Nut Retention Fastener, lb-ft (Nm) ............... 60-70 (81.3-94.9)
Spark Plug Core Thread Shell, lb-ft (Nm) ............... 25-30 (33.9-40.7)
Main Bearing Retainer Plate Screws, lb-ft (Nm) ............... 10-12 (13.6-16.3)
Camshaft Thrust Plate Mount Screws, lb-ft (Nm) ............... 8-10 (10.8-13.6)
Crankcase Base Oil Pan Screws, lb-ft (Nm) ............... 12-14 (16.3-19.0)
Gear Cover Housing Bolts Screws, lb-ft (Nm) ............... 10-12 (13.6-16.3)
Magneto Flange Mounting Nuts Fasteners, lb-ft (Nm) ............... 14-16 (19.0-21.7)
Governor Housing Lever Shaft Nut, lb-ft (Nm) ............... 6-8 (8.1-10.8)
Carburetor to Intake Manifold Flange Nuts, lb-ft (Nm) ............... 8-10 (10.8-13.6)
Air Shroud Shrouding Sheet Metal Screws, lb-ft (Nm) ............... 4-6 (5.4-8.1)
Fuel Tank Bracket Cradle Bolts, lb-ft (Nm) ............... 10-12 (13.6-16.3)
Oil Drain Plug Hex Head Fitting, lb-ft (Nm) ............... 18-22 (24.4-29.8)
Manifold Exhaust Pipe Nipple Junction, lb-ft (Nm) ............... 25-30 (33.9-40.7)
Breather Assembly Cap Cover Screw, lb-ft (Nm) ............... 3-5 (4.1-6.8)
Starter Motor Frame Clamp Tie Screws, lb-ft (Nm) ............... 8-10 (10.8-13.6)
Flywheel Alternator Stator Fasteners, lb-ft (Nm) ............... 5-7 (6.8-9.5)
Fuel Pump Flange Mounting Screws, lb-ft (Nm) ............... 8-10 (10.8-13.6)
Clutch Backing Plate Drive Ring Bolts, lb-ft (Nm) ............... 14-16 (19.0-21.7)

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• Wisconsin Engines Specs
  
• Wisconsin AB Specs
  
• Wisconsin ABN Specs
  
• Wisconsin AEH Specs
  
• Wisconsin AHH Specs
  

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