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Tecumseh OHH50 Engine

General Technical Data

Tecumseh OHH50 Engine Specifications

Engine Model ........... Tecumseh OHH50
Engine Type ........... 4-cycle 1-cylinder overhead valve horizontal air-cooled gasoline engine
Number of Cylinders ........... Single
Displacement, cu.in (cc) ........... 10.49 (171.93)
Cylinder Bore, in (mm) ........... 2.63 (66.7)
Piston Stroke, in (mm) ........... 1.94 (49.2)
Rated Engine Power, hp (kW) ........... 5.0 (3.7)
Rated Engine Speed, rpm ........... 3600
Crankshaft ........... Iron alloy
Cylinder ........... Cast iron alloy
Lubrication System ........... Full pressure
Air Cleaner ........... Paper/poly element
Cooling System ........... Forced air
Ignition System ........... Electronic
Electrical System Rating, Volts ........... 12

Fuel System

Fuel System Type ........... Carburetor
Carburetor ........... Float type
Governor Type ........... Mechanical

Tecumseh OHH50 Maintenance Data

Cylinder Block and Valves

Cylinder Bore Inside Diameter (Maximum), in (mm) ........... 2.626 (66.700)
Cylinder Head (Max. Out of Flatness), in (mm) ........... 0.005 (0.127)
Intake Valve Clearance, in (mm) ........... 0.004 (0.10)
Exhaust Valve Clearance, in (mm) ........... 0.004 (0.10)

Engine Oil and Filter

Engine Oil Type (Summer) ........... SAE 30, 10W-30
Engine Oil Type (Winter) ........... SAE 5W-30
API Service Classifications ........... SF, SG, SH, or SJ
Oil Capacity, qts (L) ........... 0.66 (0.62)
Air Filter Element Part Number ........... 36046/36634

Carburetor Adjustments

Main Pre-Set ........... Fixed jet
Idle Pre-Set ........... Fixed jet
Low Idle Speed, rpm ........... 1600-1800
High Idle Speed, rpm ........... 3600-3900

Ignition System

Spark Plug Type ........... Champion RN4C
Spark Plug Gap, in (mm) ........... 0.030 (0.762)
Ignition Module Air Gap, in (mm) ........... 0.013 (0.32)
Spark Plug Torque, Nm (ft-lbs) ........... 21 (28.5)

Service Intervals

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

Tecumseh OHH50 Service Specifications

Cylinder Bore (Standard), in (mm) ........... 2.625 (66.675)
Cylinder Bore (Maximum), in (mm) ........... 2.626 (66.700)
Cylinder Main Bearing Diameter, in (mm) ........... 1.0005-1.0010 (25.413-25.425)
Cylinder Cover/Flange Main Bearing Diameter, in (mm) ........... 1.0005-1.0010 (25.413-25.425)
Valve Clearance (Intake), in (mm) ........... 0.004 (0.1016)
Valve Clearance (Exhaust), in (mm) ........... 0.004 (0.1016)
Valve Seat Angle, deg ........... 46
Valve Seat Width, in (mm) ........... 0.035-0.045 (0.889-1.143)
Valve Guide Oversize Dimension (Intake), in (mm) ........... 0.2807-0.2817 (7.135-7.155)
Valve Guide Oversize Dimension (Exhaust), in (mm) ........... 0.2807-0.2817 (7.135-7.155)
Crankshaft End Play, in (mm) ........... 0.006-0.027 (0.1524-0.6858)
Crankpin Journal Diameter, in (mm) ........... 0.9995-1.0000 (25.387-25.400)
Crankshaft Main Bearing Diameter (Flywheel Side), in (mm) ........... 0.9985-0.9990 (25.362-25.375)
Crankshaft Main Bearing Diameter (PTO Side), in (mm) ........... 0.9985-0.9990 (25.362-25.375)
Connecting Rod Diameter (Crank Bearing), in (mm) ........... 1.0005-1.0010 (25.413-25.425)
Camshaft Bearing Diameter, in (mm) ........... 0.4970-0.4975 (12.624-12.637)
Piston Diameter (Bottom Of Skirt), in (mm) ........... 2.6204-2.6220 (66.558-66.599)
Ring Groove Side Clearance (Compession Rings), in (mm) ........... 0.0020-0.0050 (0.051-0.127)
Ring Groove Side Clearance (Oil Ring), in (mm) ........... 0.0005-0.0035 (0.013-0.089)
Piston Skirt to Cylinder Clearance, in (mm) ........... 0.0030-0.0056 (0.076-0.142)
Ring End Gap, in (mm) ........... 0.007-0.017 (0.178-0.432)

Tecumseh OHH50 Torque Specifications

Cylinder Head Bolts, ft-lbs (Nm) ........... 19.0 (26.0)
Connecting Rod Bolts, ft-lbs (Nm) ........... 9.0 (12.0)
Cylinder Cover or Flange, ft-lbs (Nm) ........... 9.5 (13.0)
Flywheel Nut, ft-lbs (Nm) ........... 35.0 (51.0)
Flywheel Nut (Cast Iron), ft-lbs (Nm) 46.0 (62.0)
Spark Plug, ft-lbs (Nm) ........... 21.0 (28.0)
Ignition Mounting (Direct to Cylinder), ft-lbs (Nm) ........... 3.7 (5.0)
Intake Pipe to Head, ft-lbs (Nm) ........... 9.6 (13.0)
Carburetor to Intake Pipe, ft-lbs (Nm) ........... 5.9 (8.0)
Muffler Mtg., ft-lbs (Nm) ........... 8.5 (11.5)
Recoil Starter, ft-lbs (Nm) ........... 4.1 (5.5)
Electric Starter to Cylinder, ft-lbs (Nm) ........... 8.2 (11.0)
Rocker Arm Stud Lock Nut, ft-lbs (Nm) ........... 10.0 (13.5)
Rocker Box Cover, ft-lbs (Nm) ........... 3.3 (4.5)
Alt. Coil Assy to Cylinder, ft-lbs (Nm) ........... 5.2 (7.0)