The Briggs and Stratton 331877 Intek Plus Platinum is a 540 cc (32.9 cu·in) single-cylinder air-cooled four-stroke internal combustion gasoline engine, manufactured by Briggs and Stratton.
The B&S 331877 engine has an OHV (overhead) design and a vertical PTO shaft. This engine is equipped with float type carburetor, pulse type fuel pump and an electronic ignition system. The B&S 331877 engine used a paper air filter with a foam pre-cleaner. It is equipped with an electric starter (12V).
The cylinder bore is 94.0 mm (3.7 in) and the piston stroke is 77.8 mm (3.06 in). This engine produced 21.4 PS (15.7 KW; 21.0 HP) at 3,600 rpm of horsepower.
The breakdown of the engine code is as follows:
- 33 – Displacement
- 1 – Basic design series
- 8 – Vertical PTO-shaft
- 7 – Plain bearing, Pressure lubrication
- 7 – Electric starter
General information
| Engine Specifications | |
| Model | B&S 331877 Intek Plus Platinum |
| Type | 4-stroke, OHV, single-cylinder |
| Displacement | 540 cm 3 (32.9 cu-in) |
| Max. horsepower | 21.4 PS (15.7 KW; 21.0 HP) at 3,600 rpm |
| Max. torque | – |
| Fuel system | Float type carburetor |
| Cooling system | Forced-air |
| Ignition system | Electronic |
| Lubricating system | Full pressure |
| Starting system | Electric starter |
| Fuel used | Gasoline |
| Fuel tank capacity | – |
Cylinder Block and Head
| Cylinder block | ||
| Bore x Stroke | 94.0 mm X 77.8 mm (3.70 x 3.06 in) | |
| Sleeve internal diameter | 94.010-94.110 mm (3.7012-3.7051 in) | |
| Number of piston rings (compression / oil): | 2 / 1 | |
| Side clearance | Top | 0.051-0.076 mm (0.002-0.003 in) |
| Second | 0.051-0.076 mm (0.002-0.003 in) | |
| Oil | 0.051-0.076 mm (0.002-0.003 in) | |
| Ring end gap | Top | 0.150-0.250 mm (0.0059-0.0098 in) |
| Second | 0.300-0.510 mm (0.0118-0.0201 in) | |
| Oil | 0.510-0.630 mm (0.0201-0.0248 in) | |
| Connecting rod small end ID | 15.890-15.920 mm (0.6256-0.6268 in) | |
| Piston pin outer diameter | 15.850-15.890 mm (0.624-0.6256 in) | |
| Cylinder Head | ||
| Valve Arrangement: | OHV (overhead) | |
| Valves: | 2 | |
| Valve steam diameter | INTAKE | 5.920-5.970 mm (0.233-0.235 in) |
| EXHAUST | 5.920-5.970 mm (0.233-0.235 in) | |
Tightening torque specs
| Tightening torque specs | |
| Air cleaner base | 6.0 Nm; 4.4 ft·lb |
| Alternator | 2.0 Nm; 1.5 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 | 8.0 Nm; 5.9 ft·lb |
| Carburetor solenoid | 5.0 Nm; 3.7 ft·lb |
| Connecting rod | 17.0 Nm; 12.6 ft·lb |
| Control bracket | 5.0 Nm; 3.7 ft·lb |
| Crankcase sump | 25.0 Nm; 18.5 ft·lb |
| Cylinder head | 25.0 Nm; 18.5 ft·lb |
| Cylinder shield | 5.0 Nm; 3.7 ft·lb |
| Exhaust manifold / adapter | 19.0 Nm; 14.0 ft·lb |
| Flywheel nut | 135.0 Nm; 100.0 ft·lb |
| Flywheel fan | 16.0 Nm; 11.9 ft·lb |
| Fuel pump | 10.0 Nm; 7.4 ft·lb |
| Governor lever nut | 5.0 Nm; 3.7 ft·lb |
| Intake manifold to cylinder head | 10.0 Nm; 7.4 ft·lb |
| Muffler | 10.0 Nm; 7.4 ft·lb |
| Oil drain plug | 11.0 Nm; 8.1 ft·lb |
| Oil fill tube | 10.0 Nm; 7.4 ft·lb |
| Oil pump cover | 10.0 Nm; 7.4 ft·lb |
| Regulator / Rectifier | 5.0 Nm; 3.7 ft·lb |
| Rewind starter | 3.0 Nm; 2.2 ft·lb |
| Rocker ball set screw or nut | 5.0 Nm; 3.7 ft·lb |
| Rocker cover | 7.0 Nm; 5.2 ft·lb |
| Starter motor | 16.0 Nm; 11.9 ft·lb |
Service Information
| Engine | |
| Max speed | 3,600 rpm |
| Valve clearance | |
| Intake valve clearance | 0.08-0.13 mm (0.003-0.005 in) |
| Exhaust valve clearance | 0.13-0.18 mm (0.005-0.007 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) | 1.40 L (1.48 US. qt, 1.23 Imp. qt.) |
| Ignition system | |
| Spark plug | Champion RC12YC |
| Spark plug gap | 0.7-0.8 mm (0.0276-0.0315 in) |
Author:
I appreciate the information, was a lot of help thank you.
Thank you, exactly what I was looking for.
Thanks for having all of this information in one place. This was very helpful and much appreciated.
Thank you very much for this specific info on my engine. The B&S web info is very vague and not specific to a unique engine. Very helpful and much appreciated.
What would be the air gap between the magneto and coil on a Briggs and Stratton model 331877 engine?
A normal heavy paper business card works perfectly. Used this method many, many times with great success.
A normal heavy paper business card works perfectly. Used this method many, many times with great success.
This was a big help!
Thank you.Awesome website.Exactly what I needed.
What would be a good replacement engine? Mine has a broken camshaft
i have a 331887 engine , but there is no way to adjust the valves .
it appears to have hydralic lifters .
how the hell do you adjust the valves .defective
Already thank you for your collaboration on behalf of all those who do not have the possibility to pay a mechanic profísional. If possible can you inform me that in briggs & stratton 331877 type 0979 B-1
what is the difference between the two compression rings of the piston?
I know that the second ring has a dot and that this dot is mounted up, the first ring does not have this dot and accidentally disassembled the first ring to measure the end gap and did not take sense in position, I look at the ring and see it is squared (faces with the diameter) Can it be mounted both sides up? Once again thank you very much