Tecumseh HH100

Tecumseh HH100The Tecumseh HH100 is a 389 cc, (23.7 cu·in) natural aspirated single-cylinder four-stroke air-cooled internal combustion small gasoline engine with a horizontal shaft, manufactured by TecumsehPower Company, for general-purpose applications.

An 84.1 mm (3.31 in) cylinder bore and 69.8 mm (2.75 in) piston stroke give the HH100 engine a total of 389 cc of displacement. This engine produced 10.2 PS (7.5 kW; 10.0 HP) of horsepower.

The Tecumseh HH100 features:

  • Cast-iron cylinder block and cast-iron cylinder head
  • L-head (side-valve) design
  • Solid state ignition system (CDI)
  • Carburetor (Tecumseh or Walbro)
  • Centrifugal governor
  • Splash type lubrication system
  • Forced air cooling system
  • Electric starter

General information

Engine Specifications
Engine model HH100
Engine type 4-stroke, L-head, single-cylinder
Displacement 389 cm3, (23.7 cu·in)
Max. horsepower 10.2 PS (7.5 kW; 10.0 HP)
Max. torque
Cooling system Forced air
Lubricating system Splash
Ignition system Solid state ignition system (CDI)
Fuel system Carburetor (Tecumseh or Walbro)
Starting system Electric starter
Governor Centrifugal governor
Dimensions (L x W X H)
Dry weight

Cylinder Block and Head

Cylinder block
Cylinder bore: 84.1 mm (3.31 in)
Piston stroke: 69.8 mm (2.75 in)
Cylinder internal diameter (standard): 84.125-84.150 mm (3.312-3.313 in)
Piston skirt outer diameter (standard): 84.023-84.074 mm (3.308-3.31 in)
Number of piston rings (compression / oil): 2/1
Piston pin diameter: 17.457-17.463 mm (0.6873-0.6875 in)
Side clearance (Top): 0.051-0.889 mm (0.002-0.035 in)
Side clearance (Second): 0.051-0.889 mm (0.002-0.035 in)
Ring end gap (Top): 0.178-0.508 mm (0.007-0.02 in)
Ring end gap (Second): 0.178-0.508 mm (0.007-0.02 in)
Crankpin journal diameter: 34.925-34.938 mm (1.375-1.3755 in)
Crankshaft center distance: 34.9 mm (1.375 in)
Cylinder head
Valve arrangement: L-head (side valve)
Valves: 2
Valve spring free length (INTAKE): 47.879 mm (1.885 in)
Valve spring free length (EXHAUST): 47.879 mm (1.885 in)
Camshaft lobe height (INTAKE): 33.134-33.236 mm (1.3045-1.3085 in)
Camshaft lobe height (EXHAUST): 33.134-33.236 mm (1.3045-1.3085 in)

Service Data

Valve clearance
Intake valve clearance: 0.254 mm (0.01 in)
Exhaust valve clearance: 0.508 mm (0.02 in)
Oil system
Lubrication system: Splash
Oil type: API service SF or SJ
Recommended oil: SAE 10-W30
Oil capacity: 1.56 L (1.65 US. qt, 1.37 Imp. qt.)
Fuel system
Type: Carburetor Tecumseh or Walbro
Main adjustment screw: Tecumseh: 1-3/4 turns
Walbro: 1-1/2 turns off seat
Idle adjustment screw: Tecumseh: 1-1/4 turns
Walbro: 1-1/4 turns off seat
Ignition system
Type: Solid state ignition system (CDI)
Spark plug: Champion J-8
Spark plug gap: 0.763 mm (0.03 in)
Spark plug torque: 30 N·m (3.1 kg·m, 22.1 ft·lb)
Magneto air gap 0.152-0.254 mm (0.006-0.010 in)

Tightening torque

Tightening torque specs
Cylinder head bolts 20.3-27.1 Nm (15.0-20.1 ft-lbs)
Connecting rod lock nuts 9.7-12.4 Nm (7.2-9.2 ft-lbs)
Mounting flange or cylinder cover 11.3-14.7 Nm (8.4-10.9 ft-lbs)
Flywheel nut 67.8-74.6 Nm (50.2-55.3 ft-lbs)
Spark plug 24.9-31.6 Nm (18.4-23.4 ft-lbs)
Carburetor to cylinder (8.1-10.9 Nm (6.0-8.1 ft-lbs)
Air cleaner to elbow 1.7-2.8 Nm (1.3-2.1 ft-lbs)
Air cleaner bracket to carburetor 1.7-2.8 Nm (1.3-2.1 ft-lbs)
Tank bracket to housing 4-5.7.0 Nm (3.0-4.2 ft-lbs)
Tank bracket to cylinder (5/16’’lower) 17.0-22.6 Nm (12.6-16.7 ft-lbs)
Tank bracket to head bolt 17.0-22.6 Nm (12.6-16.7 ft-lbs)
Starter-Top mount recoil 4.5-6.8 Nm (3.3-5.0 ft-lbs)
Belt guard to blower housing 2.8-4.0 Nm (2.1-3.0 ft-lbs)
Flywheel screen and pulley 8.1-10.9 Nm (6.0-8.1 ft-lbs)
Stationary point screw 1.7-2.3 Nm (1.3-1.7 ft-lbs)
Blower housing baffle to cylinder 8.1-10.9 Nm (6.0-8.1 ft-lbs)
Blower housing to baffle or cylinder 5.4-8.1 Nm (4.0-6.0 ft-lbs)
Breaker point cover 1.7-2.8 Nm (1.3-2.1 ft-lbs)
Magneto stator mounting 8.1-10.9 Nm (6.0-8.1 ft-lbs)
Breather to cylinder 2.3-2.8 Nm (1.7-2.1 ft-lbs)
Oil drain plug 3/8-18 9.0-11.3 Nm (6.7-8.3 ft-lbs)
Blower housing extension to cylinder 8.1-10.9 Nm (6.0-8.1 ft-lbs)
Stub shaft bolts to flywheel 11.3-14.1 Nm (8.4-10.4 ft-lbs)
Motor generator all mounting bolts 7.4-11.3 Nm (5.5-8.4 ft-lbs)


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We try to use official documentation and verify the published data, but errors may occur. In addition, specifications of machinery and equipment may vary depending on markets and modifications. We do not recommend the use of this data for spare parts or repairs. Use official service manuals or parts catalogs for your product.

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