Briggs and Stratton 42A707

The 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

Engine
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)