Briggs and Stratton 42A707

Briggs and Stratton 42A707The Briggs and Stratton 42A707 is a 694 cc, (42.35 cu·in) natural aspirated two-cylinder four-stroke air-cooled internal combustion small gasoline engine with a vertical shaft, for general-purpose applications.

Cylinder bore is 87.3 mm (3.44 in) and piston stroke is 58.0 mm (2.28 in). The Briggs and Stratton 42A707 engine produced 18.1 PS (13.3 kW; 18.0 HP) at 3,600 rpm of maximum output power and 38.6 N·m (3.9 kg·m, 28.4 ft·lb) at 2,600 rpm of peak torque.

The Briggs and Stratton 42A707 features:

  • L-head design
  • Flywheel magneto ignition system
  • Float type carburetor
  • Mechanical governor
  • Full pressure lubrication system
  • Forced air cooling system
  • Electric starter

General information

Engine Specifications
Engine model B&S 42A707
Engine type 4-stroke, L-head, two-cylinder, opposed
Displacement 694 cm3, (42.35 cu·in)
Max. horsepower 18.1 PS (13.3 kW; 18.0 HP) at 3,600 rpm
Max. torque 38.6 N·m (3.9 kg·m, 28.4 ft·lb) at 2,600 rpm
Cooling system Forced air
Air cleaner Paper cartridge with a foam pre-cleaner
Lubricating system Full pressure
Ignition system Flywheel magneto
Fuel system Float type carburetor
Fuel used Gasoline
Starting system Electric starter
Governor Mechanical governor

Cylinder Block and Head

Cylinder block
Cylinder bore: 87.3 mm (3.44 in)
Piston stroke: 58.0 mm (2.28 in)
Cylinder internal diameter (standard): 87.280-87.310 mm (3.4362-3.4374 in)
Number of piston rings (compression / oil): 2/1
Connecting rod big end diameter (standard): 41.270-41.280 mm (1.6248-1.6252 in)
Connecting rod small end diameter (standard): 20.340-20.350 mm (0.8008-0.8012 in)
Piston pin diameter: 20.320-20.330 mm (0.8-0.8004 in)
Side clearance (Top): 0.090-0.150 mm (0.0035-0.0059 in)
Side clearance (Second): 0.090-0.150 mm (0.0035-0.0059 in)
Side clearance (Oil): 0.090-0.150 mm (0.0035-0.0059 in)
Ring end gap (Top): 0.180-0.430 mm (0.0071-0.0169 in)
Ring end gap (Second): 0.180-0.430 mm (0.0071-0.0169 in)
Ring end gap (Oil): 0.180-0.430 mm (0.0071-0.0169 in)
Crankshaft main journal diameter: 34.990-35.010 mm (1.3776-1.3783 in)
Crankpin journal diameter: 41.230-41.250 mm (1.6232-1.624 in)
Crankshaft center distance: 29.0 mm (1.14 in)
Cylinder head
Valve arrangement: L-head, gear driven
Valves: 2(4 valves in total)
Valve steam diameter (INTAKE): 7.820-7.870 mm (0.3079-0.3098 in)
Valve steam diameter (EXHAUST): 7.820-7.870 mm (0.3079-0.3098 in)
Camshaft lobe height (INTAKE): 29.270-29.350 mm (1.1524-1.1555 in)
Camshaft lobe height (EXHAUST): 28.500-28.580 mm (1.122-1.1252 in)
Camshaft journal diameter : 15.850-15.870 mm (0.624-0.6248 in)

Tightening torque

Tightening torque specs
Alternator (to cylinder) 2.0 Nm; 1.5 ft·lb
Air cleaner base (to carburetor) 3.0 Nm; 2.2 ft·lb
Armature 3.0 Nm; 2.2 ft·lb
Blower housings 10.0 Nm; 7.4 ft·lb
Breather 3.0 Nm; 2.2 ft·lb
Carburetor to intake manifold 11.0 Nm; 8.1 ft·lb
Connecting rod 22.0 Nm; 16.3 ft·lb
Crankcase sump/cover 25.0 Nm; 18.5 ft·lb
Cylinder head 18.0 Nm; 13.3 ft·lb
Carburetor to solenoid 11.0 Nm; 8.1 ft·lb
Fan Retainer 17.0 Nm; 12.6 ft·lb
Flywheel nut 203.0 Nm; 150.0 ft·lb
Governor lever nut 11.0 Nm; 8.1 ft·lb
Intake manifold to cylinder head 10.0 Nm; 7.4 ft·lb
Starter motor 18.0 Nm; 13.3 ft·lb

Service Data

Valve clearance
Intake valve clearance): 0.15-0.20 mm (0.006-0.008 in)
Exhaust valve clearance: 0.23-0.28 mm (0.009-0.011 in)
Oil system
Lubrication system: Full pressure
Oil type: SC, SD, SE or higher
Recommended oil: Summer: SAE 30, 10W-30
Winter: SAE 5W-30
Oil capacity: 1.70 L (1.8 US. qt, 1.5 Imp. qt.)
Fuel system
Type: Float type carburetor
Ignition system
Type: Flywheel magneto
Spark plug: Champion RJ-12,
AC R-46,
Autolite 308
Spark plug gap: 0.7-0.8 mm (0.0276-0.0315 in)
Spark plug torque: 22 N·m (2.2 kg·m, 16.2 ft·lb)
Point gap 0.51 mm (0.020 in)

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