The Briggs and Stratton 303777 Vanguard is a 495 cc, (30.2 cu·in) natural aspirated two-cylinders four-stroke air-cooled internal combustion gasoline engine with a vertical shaft, for general-purpose applications.
Cylinder bore and piston stroke are 68.0 mm (2.68 in) and 66.0 mm (2.6 in), respectively. This engine produced 16.2 PS (11.9 kW; 16.0 HP) at 3,600 rpm of horsepower.
The B&S 303777 features:
- OHV design
- Magneto electronic ignition system
- Float type, side-draft carburetor
- Centrifugal governor
- Full pressure lubrication system with spin-on oil filter
- Forced air cooling system
- Electric starter
General information
| Engine Specifications | |
| Engine model | 303777 Vanguard |
| Engine type | 4-stroke, OHV, V-twin |
| Displacement | 495 cm3, (30.2 cu·in) |
| Max. horsepower | 16.2 PS (11.9 kW; 16.0 HP) at 3,600 rpm |
| Max. torque | – |
| Cooling system | Forced air |
| Air cleaner | Paper element with a foam pre-cleaner |
| Lubricating system | Full pressure lubrication with spin-on oil filter |
| Ignition system | Magneto electronic |
| Fuel system | Float type, side-draft carburetor |
| Fuel used | Gasoline |
| Starting system | Electric starter |
| Governor | Centrifugal governor |
| Charging system | Alternator 12V, 16A |
| Dimensions (L x W X H) | – |
| Dry weight | – |
Cylinder Block and Head
| Cylinder block | |
| Compression ratio: | 8.2:1 |
| Cylinder bore: | 68.0 mm (2.68 in) |
| Piston stroke: | 66.0 mm (2.6 in) |
| Cylinder internal diameter (standard): | 68.000-68.030 mm (2.6772-2.6783 in) |
| Number of piston rings (compression / oil): | 2/1 |
| Connecting rod big end diameter (standard): | 37.060-37.080 mm (1.4591-1.4598 in) |
| Connecting rod small end diameter (standard): | 17.090-17.100 mm (0.6728-0.6732 in) |
| Piston pin diameter: | 17.070-17.080 mm (0.672-0.6724 in) |
| Side clearance (Top): | 0.045-0.076 mm (0.0018-0.003 in) |
| Side clearance (Second): | 0.045-0.076 mm (0.0018-0.003 in) |
| Side clearance (Oil): | 0.110-0.150 mm (0.0043-0.0059 in) |
| Ring end gap (Top): | 0.200-0.400 mm (0.0079-0.0157 in) |
| Ring end gap (Second): | 0.200-0.400 mm (0.0079-0.0157 in) |
| Ring end gap (Oil): | 0.200-0.400 mm (0.0079-0.0157 in) |
| Crankshaft main journal diameter (magneto side): | 29.980-30.000 mm (1.1803-1.1811 in) |
| Crankshaft main journal diameter (PTO side): | 34.960-34.970 mm (1.3765-1.3770 in) |
| Crankpin journal diameter: | 37.000-37.020 mm (1.4567-1.4575 in) |
| Crankshaft center distance: | 33.0 mm (1.3 in) |
| Cylinder head | |
| Valve arrangement: | OHV, gear driven |
| Valves: | 2 (4 valves in total) |
| Valve steam diameter (INTAKE): | 5.950-5.960 mm (0.2343-0.2346 in) |
| Valve steam diameter (EXHAUST): | 5.940-5.950 mm (0.2339-0.2343 in) |
| Camshaft lobe height (INTAKE): | 30.330-30.530 mm (1.1941-1.202 in) |
| Camshaft lobe height (EXHAUST): | 30.330-30.530 mm (1.1941-1.202 in) |
| Camshaft journal diameter (magneto side): | 15.950-15.970 mm (0.628-0.6287 in) |
| Camshaft journal diameter (PTO side): | 19.940-19.960 mm (0.785-0.7858 in) |
Tightening torque
| Tightening torque specs | |
| Alternator (to cylinder) | 2.0 Nm; 1.5 ft·lb |
| Air cleaner base (to carburetor) | 7.0 Nm; 5.2 ft·lb |
| Air cleaner support bracket | 7.0 Nm; 5.2 ft·lb |
| Alternator | 2.0 Nm; 1.5 ft·lb |
| Armature | 3.0 Nm; 2.2 ft·lb |
| Blower housings | 7.0 Nm; 5.2 ft·lb |
| Back plate | 7.0 Nm; 5.2 ft·lb |
| Breather | 3.0 Nm; 2.2 ft·lb |
| Carburetor to manifold | 7.0 Nm; 5.2 ft·lb |
| Connecting rod | 13.0 Nm; 6.9 ft·lb |
| Crankcase cover | 17.0 Nm; 12.6 ft·lb |
| Cylinder head | 19.0 Nm; 14.1 ft·lb |
| Cylinder shield | 7.0 Nm; 5.2 ft·lb |
| Exhaust manifold | 17.0 Nm; 12.6 ft·lb |
| Flywheel nut | 175.0 Nm; 129.6 ft·lb |
| Fan Retainer | 17.0 Nm; 12.6 ft·lb |
| Governor lever nut | 8.0 Nm; 5.9 ft·lb |
| Governor control bracket | 16.0 Nm; 11.9 ft·lb |
| Intake manifold to cylinder head | 16.0 Nm; 11.9 ft·lb |
| Oil pump | 7.0 Nm; 5.2 ft·lb |
| Rewind starter (to blower housing) | 7.0 Nm; 5.2 ft·lb |
| Rocker arm lock nut | 7.0 Nm; 5.2 ft·lb |
| Rocker arm stud | 11.0 Nm; 8.2 ft·lb |
| Starter motor | 16.0 Nm; 11.9 ft·lb |
| Starter motor thru bolts | 6.0 Nm; 4.4 ft·lb |
| Valve cover | 3.0 Nm; 2.2 ft·lb |
Service Data
| Valve clearance | |
| Intake valve clearance: | 0.10-0.15 mm (0.004-0.006 in) |
| Exhaust valve clearance: | 0.10-0.15 mm (0.004-0.006 in) |
| Oil system | |
| Lubrication system: | Full pressure by gear-driven oil pump |
| Oil type: | SF, SG, SH, SJ or higher |
| Recommended oil: | Summer: SAE 30W, 10W-30 Winter: SAE 5W-30 |
| Oil capacity: | 1.66 L (1.75 US. qt, 1.46 Imp. qt.) |
| Fuel system | |
| Type: | Float type, side-draft carburetor |
| Ignition system | |
| Type: | Electronic |
| Spark plug: | Champion RC12YC |
| Spark plug gap: | 0.7-0.8 mm (0.0276-0.0315 in) |
| Spark plug torque: | 23 N·m (2.3 kg·m, 17 ft·lb) |
| Armature air gap | 0.2-0.3 mm (0.008-0.012 in) |
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