Tecumseh HH100

Tecumseh HH100The Tecumseh HH100 is a 389 cc (23.7 cu·in) single-cylinder air-cooled four-stroke internal combustion gasoline engine, manufactured by Tecumseh.

The Tecumseh HH100 engine has an L-head (side valve) design, horizontal PTO shaft, cast-iron cylinder block, and cast-iron cylinder head. This engine can be equipped with Tecumseh or Walbro carburetor and solid-state ignition system (CDI).

The cylinder bore is 84.1 mm (3.31 in) and the piston stroke is 69.8 mm (2.75 in). Compression ratio rating is 6.70:1. This engine produced 10.2 PS (7.5 kW; 10.0 HP) of horsepower.

The breakdown of the engine code is as follows:

  • HH – Horizontal-Heavy Duty
  • 100 – 10.0 HP

General information

Engine Specifications
Type4-stroke, L-head, single cylinder
Displacement389 cm3 (23.7 cu-in)
Max. horsepower10.2 PS (7.5 kW; 10.0 HP)
Max. torque (crank PTO)
Fuel systemCarburetor (Tecumseh or Walbro)
Cooling systemForced-air
Ignition systemSolid-state ignition system (CDI)
Lubricating systemSplash type
Starting systemRecoil or electric starter
Fuel usedUnleaded gasoline (octane number 86 or higher)
Fuel tank capacity

Cylinder Block and Head

Cylinder block
Bore x Stroke84.1 X 69.8 mm (3.31 x 2.75 in)
Sleeve internal diameter84.125-84.150 mm (3.312-3.313 in)
Piston skirt outer diameter84.023-84.074 mm (3.308-3.310 in)
Number of piston rings (compression / oil):2 / 1
Ring end gapTop0.178-0.508 mm (0.007-0.02 in)
Second0.178-0.508 mm (0.007-0.02 in)
Piston pin outer diameter17.457-17.463 mm (0.6873-0.6875 in)
Cylinder Head
Valve Arrangement:L-head (sidevalve)
Valve spring free length:47.879 mm (1.885 in)
Camshaft lobe diameter:33.134-33.236 mm (1.3045-1.3085 in)

Tightening torque specs

Tightening torque specs
Cylinder head bolt20.3-27.1 Nm; 2.07-2.76 kg·m; 15-20 ft·lb
Flywheel nut67.8-74.6 Nm; 6.9-7.6 kg·m; 50-55 ft·lb
Spark plug25-30 Nm; 2.55-3.06 kg·m; 18-22 ft·lb

Service Information

Valve clearance
Intake valve clearance0.254 mm (0.010 in)
Exhaust valve clearance0.508 mm (0.020 in)
Oil system
Oil typeAPI SF, SJ
Recommended oilSAE 30, 10-W30
Oil capacity1.4 liters (1.5 US.qts, 1.23 Imp. qts)
Ignition system
Spark plugChampion J-8
Spark plug gap0.763 mm (0.03 in)
Fuel system
TypeCarburetor (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
Author: Sergei Wers
About: Co-founder and CEO of a multi-brand auto repair shop (engine repair, chassis repair, body repair and painting) for over 15 years. I have been developing internet sites with technical specifications for more than seven years.

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We try to use verified sources and official documentation, however, differences between sources or errors in entering information may occur. We do not provide advice on technical issues related to the engines operation or repair. We do not recommend using provided information for engines repairing engines or spare parts ordering, use only official service manuals and spare-parts catalogs.


  1. Do have a pin and seat kit for LME 29 Walbro Carburetor .
    And an after market carburetor.
    For Sears 10xl 1971 riding mower.
    A Service Main Nozzle, under cut.
    Fixed High speed nut and pin
    Float damper spring

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