Briggs and Stratton 42A707

Briggs and Stratton 42A707The Briggs and Stratton 42A707 is a 694 cc (42.35 cu·in) two-culinder air-cooled four-stroke internal combustion gasoline engine, manufactured by Briggs and Stratton.

The B&S 42A707 engine has an L-head (side valve) design and a vertical PTO shaft. This engine is equipped with float type carburetor and a flywheel magneto ignition system. The B&S 42A707 engine used a full pressure lubrication system.

A 87.3 mm (3.44 in) cylinder bore and 58.0 mm (2.28 in) piston stroke give the B&S 42A707 engine a total of 694 cc of displacement.

This engine produced 18.1 PS (13.3 kW; 18.0 HP) at 3,600 rpm of horsepower and 38.7 N·m (3.9 kg·m, 28.4 ft·lb) at 2,600 rpm of torque.

The breakdown of the engine code is as follows:

  • 42 – Displacement
  • A – Basic design series
  • 7 – Vertical PTO-shaft
  • 0 – Ball bearing
  • 7 – Electric starter

General information

Engine Specifications
Model B&S 42A707
Type 4-stroke, L-head, opposed-twin
Displacement 694 cm 3 (42.3 cu-in)
Max. horsepower 18.1 PS (13.3 kW; 18.0 HP) at 3,600 rpm
Max. torque 38.7 N·m (3.9 kg·m, 28.4 ft·lb) at 2,600 rpm
Fuel system Float type carburetor
Cooling system Forced-air
Ignition system Flywheel magneto
Lubricating system Full pressure lubrication
Starting system Electric starter
Fuel used Gasoline
Fuel tank capacity

Cylinder Block and Head

Cylinder block
Bore x Stroke 87.3 mm X 58.0 mm (3.44 x 2.28 in)
Sleeve internal diameter 87.280-87.310 mm (3.4362-3.4374 in)
Number of piston rings (compression / oil): 2 / 1
Side clearance Top 0.090-0.150 mm (0.0035-0.0059 in)
Second 0.090-0.150 mm (0.0035-0.0059 in)
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)
Second 0.180-0.430 mm (0.0071-0.0169 in)
Oil 0.180-0.430 mm (0.0071-0.0169 in)
Connecting rod small end ID 20.340-20.350 mm (0.8008-0.8012 in)
Piston pin outer diameter 20.320-20.330 mm (0.8000-0.8004 in)
Cylinder Head
Valve Arrangement: L-head
Valves: 4 (2 per cylinder)
Valve steam diameter INTAKE 7.820-7.870 mm (0.3079-0.3098 in)
EXHAUST 7.820-7.870 mm (0.3079-0.3098 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 Information

Max speed 3,600 rpm
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
Oil type API SF, SG, SH, SJ or higher
Recommended oil Summer: SAE 30, 10W-30
Winter: SAE 5W-30
Oil capacity (with filter) 1.70 L (1.8 US. qt, 1.5 Imp. qt.)
Ignition system
Spark plug Champion RJ-12, AC R-46, Autolite 308
Spark plug gap 0.7-0.8 mm (0.0276-0.0315 in)
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