Briggs and Stratton 402437

Briggs and Stratton 402437The Briggs and Stratton 402437 is a 655 cc (40.0 cu·in) two-cylinder air-cooled four-stroke internal combustion gasoline engine, manufactured by Briggs and Stratton.

The B&S 402437 engine has an L-head (sidevalve) design and a horizontal PTO shaft. This engine is equipped with float type carburetor and a flywheel magneto ignition system.

A 87.3 mm (3.44 in) cylinder bore and 55.0 mm (2.16 in) piston stroke give the B&S 402437 engine a total of 655 cc of displacement.

This engine produced 16.2 PS (11.9 kW; 16.0 HP) at 3,600 rpm of horsepower and 34.8 N·m (3.5 kg·m, 25.6 ft·lb) at 2,700 rpm of torque.

General information

Engine Specifications
ModelB&S 402437
Type4-stroke, L-head, opposed two-cylinder
Displacement655 cm 3 (40.0 cu-in)
Max. horsepower16.2 PS (11.9 kW; 16.0 HP) at 3,600 rpm
Max. torque34.8 N·m (3.5 kg·m, 25.6 ft·lb) at 2,700 rpm
Fuel systemFloat type carburetor
Cooling systemForced-air
Ignition systemFlywheel magneto
Lubricating systemFull pressure lubrication
Starting systemElectric starter
Fuel usedGasoline
Fuel tank capacity

Cylinder Block and Head

Cylinder block
Bore x Stroke87.3 mm X 55.0 mm (3.44 x 2.16 in)
Sleeve internal diameter87.280-87.310 mm (3.4362-3.4374 in)
Number of piston rings (compression / oil):2 / 1
Side clearanceTop0.090-0.150 mm (0.0035-0.0059 in)
Second0.090-0.150 mm (0.0035-0.0059 in)
Oil0.090-0.150 mm (0.0035-0.0059 in)
Ring end gapTop0.180-0.430 mm (0.0071-0.0169 in)
Second0.180-0.430 mm (0.0071-0.0169 in)
Oil0.180-0.430 mm (0.0071-0.0169 in)
Connecting rod small end ID20.340-20.350 mm (0.8008-0.8012 in)
Piston pin outer diameter20.320-20.330 mm (0.8-0.8004 in)
Cylinder Head
Valve Arrangement:L-head
Valves:4 (2 per cylinder)
Valve steam diameterINTAKE7.820-7.870 mm (0.3079-0.3098 in)
EXHAUST7.820-7.870 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
Armature3.0 Nm; 2.2 ft·lb
Blower housings10.0 Nm; 7.4 ft·lb
Breather3.0 Nm; 2.2 ft·lb
Carburetor to intake manifold11.0 Nm; 8.1 ft·lb
Connecting rod22.0 Nm; 16.3 ft·lb
Crankcase sump/cover25.0 Nm; 18.5 ft·lb
Cylinder head18.0 Nm; 13.3 ft·lb
Carburetor to solenoid11.0 Nm; 8.1 ft·lb
Fan Retainer17.0 Nm; 12.6 ft·lb
Flywheel nut203.0 Nm; 150.0 ft·lb
Governor lever nut11.0 Nm; 8.1 ft·lb
Intake manifold to cylinder head10.0 Nm; 7.4 ft·lb
Starter motor18.0 Nm; 13.3 ft·lb

Service Information

Max speed3,600 rpm
Oil system
Oil typeAPI 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 plugChampion RJ-12, AC R-46, Autolite 308
Spark plug gap0.7-0.8 mm (0.0276-0.0315 in)
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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