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Tecumseh HH120 Engine

General Technical Data

Tecumseh HH120 Engine Specifications

Engine Model ........... Tecumseh HH120
Engine Type ........... 4-cycle L-head single-cylinder horizontal heavy duty air-cooled gasoline engine
Number of Cylinders ........... 1
Displacement, cu.in (cc) ........... 27.66 (453.4)
Cylinder Bore, in (mm) ........... 3.50 (88.9)
Piston Stroke, in (mm) ........... 2.88 (73.0)
Rated Engine Power, hp (kW) ........... 12.0 (8.9)
Rated Engine Speed, rpm ........... 3600
Maximum Torque, Nm (ft-lbs) ........... 25.4 (18.8)
Torque Speed, rpm ........... 2600
Lubrication System ........... Splash type
Air Cleaner ........... Paper element
Cooling System ........... Forced air
Ignition System ........... Magneto with dust and moisture seal
Starting System ........... Recoil or electric starter
Crankshaft ........... Iron alloy
Cylinder ........... Cast iron alloy
Electrical System Rating, Volts ........... 12

Fuel System

Fuel System Type ........... Carburetor
Carburetor Type ........... Float, adjustable jet
Governor Type ........... Mechanical

Dimensions and Weight

Overall Length, in (mm) ........... 18.3 (463)
Overall Width, in (mm) ........... 12.4 (314)
Overall Height, in (mm) ........... 17.8 (450)
Net Weight, lbs (kg) ........... 84.0 (38.2)

Tecumseh HH120 Maintenance Data

Cylinder Block and Valves

Cylinder Bore Inside Diameter (Maximum), in (mm) ........... 3.500 (88.900)
Cylinder Head (Max. Out of Flatness), in (mm) ........... 0.005 (0.127)
Intake Valve Clearance, in (mm) ........... 0.010-0.020 (0.25-0.51)
Exhaust Valve Clearance, in (mm) ........... 0.010-0.020 (0.25-0.51)

Engine Oil and Filter

Engine Oil Type (Summer) ........... SAE 30, 10W-30
Engine Oil Type (Winter) ........... SAE 5W-30
API Service Classifications ........... SF or SJ
Oil Capacity, qts (L) ........... 1.65 (1.56)
Air Filter Element Part Number ........... 31925/32008

Carburetor Adjustments

Main Adjustment Screw ........... 1-3/4 turn
Idle Adjustment Screw ........... 1-1/4 turn
Low Idle Speed, rpm ........... 1600-1800
High Idle Speed, rpm ........... 3600-3900

Ignition System

Spark Plug Type ........... Champion RJ8C
Spark Plug Gap, in (mm) ........... 0.030 (0.762)
Breaker Point Gap, in (mm) ........... 0.020 (0.508)
Magneto Air Gap, in (mm) ........... 0.006-0.010 (0.152-0.254)
Timing Dim. BTDC, in (mm) ........... 0.095 (2.41)
Spark Plug Torque, Nm (ft-lbs) ........... 21 (28.5)

Service Intervals

Service Air Cleaner Element ........... Every 25 hrs
Change Engine Oil ........... Every 25 hrs
Clean Cooling Fins ........... Every 25 hrs
Check and Adjust Spark Plug ........... Every 100 hrs
Replace Air Cleaner Element ........... Every 100 hrs
Check Carburetor Adjustment ........... Every 100 hrs
Check and Adjust Valve Clearance ........... Every 200 hrs
Replace Spark Plug ........... Every 200 hrs

Tecumseh HH120 Service Data

Cylinder Block

Cylinder Bore (Standard), in (mm) ........... 3.500 (88.900)
Cylinder Bore (Maximum), in (mm) ........... 3.501 (88.925)
Connecting Rod Journal Diameter, in (mm) ........... 1.3750-1.3755 (34.925-34.938)
Connecting Rod Diameter (Maximum), in (mm) ........... 1.3765 (34.963)
Shaft Seat Diameter for Roller Bearings, in (mm) ........... 1.1865-1.1870 (30.137-30.150)
Piston Skirt Diameter, in (mm) ........... 3.4950-3.4970 (88.773-88.824)
Piston Pin Diameter, in (mm) ........... 0.6873-0.6875 (17.457-17.463)
Compression Ring Groove Width, in (mm) ........... 0.0950-0.0960 (2.413-2.438)
Oil Ring Groove Width, in (mm) ........... 0.1880-0.1900 (4.775-4.826)
Ring Groove Side Clearance, in (mm) ........... 0.0020-0.0035 (0.051-0.889)
Ring End Gap, in (mm) ........... 0.007-0.020 (0.178-0.508)
Top Piston Land Clearance, in (mm) ........... 0.031-0.036 (0.787-0.914)
Piston Skirt Clearance, in (mm) ........... 0.003-0.006 (0.076-0.127)
Camshaft Bearing Diameter, in (mm) ........... 0.6235-0.6240 (15.837-15.850)
Cam Lobe Diameter, in (mm) ........... 1.3045-1.3085 (33.134-33.236)

Cylinder Head and Valves

Cylinder Head (Max. Out of Flatness), in (mm) ........... 0.005 (0.127)
Intake Valve Clearance, in (mm) ........... 0.010-0.020 (0.254-0.508)
Exhaust Valve Clearance, in (mm) ........... 0.010-0.020 (0.254-0.508)
Valve Seat Angle, deg ........... 46
Valve Seat Width, in (mm) ........... 0.042-0.052 (1.067-1.321)
Valve Face Angle, deg ........... 45
Valve Face Width, in (mm) ........... 0.089-0.099 (2.261-2.515)
Valve Lip Width, in (mm) ........... 0.06 (1.524)
Valve Spring Free Length, in (mm) ........... 1.885 (47.879)
Valve Guides Diameter (Std), in (mm) ........... 0.312-0.313 (7.925-7.950)
Valve Guides Diameter (Over-Size), in (mm) ........... 0.343-0.344 (8.712-8.738)

Tecumseh HH120 Tightening Torque Specs

Cylinder Head Bolts, ft-lbs (Nm) ........... 15.0-20.1 (20.3-27.1)
Connecting Rod Lock Nuts, ft-lbs (Nm) ........... 7.2-9.2 (9.7-12.4)
Mounting Flange or Cylinder Cover, ft-lbs (Nm) ........... 8.4-10.9 (11.3-14.7)
Flywheel Nut, ft-lbs (Nm) ........... 50.2-55.3 (67.8-74.6)
Spark Plug, ft-lbs (Nm) ........... 18.4-23.4 (24.9-31.6)
Carburetor to Cylinder, ft-lbs (Nm) ........... 6.0-8.1 (8.1-10.9)
Air Cleaner to Elbow, ft-lbs (Nm) ........... 1.3-2.1 (1.7-2.8)
Air Cleaner Bracket to Carburetor, ft-lbs (Nm) ........... 1.3-2.1 (1.7-2.8)
Tank Bracket to Housing, ft-lbs (Nm) ........... 3.0-4.2 (4-5.7.0)
Tank Bracket to Cylinder (5/16'’ Lower), ft-lbs (Nm) ........... 12.6-16.7 (17.0-22.6)
Tank Bracket to Head Bolt, ft-lbs (Nm) ........... 12.6-16.7 (17.0-22.6)
Starter-Top Mount Recoil, ft-lbs (Nm) ........... 3.3-5.0 (4.5-6.8)
Belt Guard to Blower Housing, ft-lbs (Nm) ........... 2.1-3.0 (2.8-4.0)
Flywheel Screen and Pulley, ft-lbs (Nm) ........... 6.0-8.1 (8.1-10.9)
Stationary Point Screw, ft-lbs (Nm) ........... 1.3-1.7 (1.7-2.3)
Blower Housing Baffle to Cylinder, ft-lbs (Nm) ........... 6.0-8.1 (8.1-10.9)
Blower Housing to Baffle or Cylinder, ft-lbs (Nm) ........... 4.0-6.0 (5.4-8.1)
Breaker Point Cover, ft-lbs (Nm) ........... 1.3-2.1 (1.7-2.8)
Magneto Stator Mounting, ft-lbs (Nm) ........... 6.0-8.1 (8.1-10.9)
Breather to Cylinder, ft-lbs (Nm) ........... 1.7-2.1 (2.3-2.8)
Oil Drain Plug 3/8-18, ft-lbs (Nm) ........... 6.7-8.3 (9.0-11.3)
Blower Housing Extension to Cylinder, ft-lbs (Nm) ........... 6.0-8.1 (8.1-10.9)
Stub Shaft Bolts to Flywheel, ft-lbs (Nm) ........... 8.4-10.4 (11.3-14.1)
Motor Generator all Mounting Bolts, ft-lbs (Nm) ........... 5.5-8.4 (7.4-11.3)