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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