The Nissan / Datsun L20B is a carbureted 2.0 liter (1,952 cc, 119.11 cu in) straight-4, four-stroke cycle gasoline engine from Nissan L-family. The Nissan / Datsun L20B motor was produced from 1974 through 1985.
The Nissan (Datsun) L20B engine features OHC valves, wedge-shaped combustion chamber, aluminum cylinder head, and fully balanced five-bearing crankshaft. The cylinder block is cast as a single unit and features deep skirting. The engine is equipped with single, 2-barrel, downdraft carburetor that incorporates a special device to control emission.
The L20B engine has an 85.0 mm (3.35 in) cylinder bore and 86.0 mm (3.38 in) piston stroke with a compression ratio of 8.5:1.
The Nissan L20B engine produced:
- SAE Gross: 112 PS (110 HP, 82 kW) and 152 Nm (15.5 kg·m, 112 lb·ft)
- SAE Net: 98 PS (97 HP, 72 kW) and 138 Nm (14.1 kg·m, 102 lb·ft)
The breakdown of the engine code is as follows:
- L – Engine Family
- 20 – 2.0 Liter Displacement
General information
| Engine Specifications | |
| Engine code | L20B |
| Layout | Four stroke, Inline-4 (Straight-4) |
| Fuel type | Gasoline |
| Production | – |
| Displacement | 2.0 L, 1,952 cm3 (119.11 cu in) |
| Fuel system | Carburetor |
| Power adder | None |
| Max. horsepower | 112 PS (110 HP, 82 kW) |
| Max. torque | 52 Nm (15.5 kg·m, 112 lb·ft) |
| Firing order | 1-3-4-2 |
| Dimensions (L x H x W): | – |
| Weight | – |
Cylinder block
The Nissan-Datsun L20B motor has a cast-iron cylinder block. The cylinder block, a monoblock special casting structure, employs a five-bearing-support system. The cylinder bores are surrounded by cooling jackets and machined directly in the block. The oilways in the block are arranged so that the full-flow oil filter is directly attached to the right-hand side of the block. The Nissan L20B engine cylinder bore is 85.0 mm (3.35 in) and the piston stroke is 86.0 mm (3.38 in), compression ratio rating is 8.5:1.
The crankshaft is a special steel forging; fully balanced, it turns out smooth, dependable power at high speed. The engine uses eight balance weights. The pistons are special aluminum casting with struts to control thermal expansion and have two compression rings and one combined oil ring. The piston heads are slightly dished. The piston pin is a special hollow steel shaft. It is full-floating fit to the piston and press-fit to the connecting rods. The connecting rods are special forged steel.
| Cylinder block | ||
| Cylinder block alloy | Cast iron | |
| Compression ratio: | 8.5:1 | |
| Cylinder bore: | 85.0 mm (3.35 in) | |
| Piston stroke: | 86.0 mm (3.38 in) | |
| Number of piston rings (compression / oil): | 2 / 1 | |
| Number of main bearings: | 5 | |
| Cylinder inner diameter (standard): | 85.000-85.050 mm (3.3465-3.3484 in) | |
| Piston skirt diameter (standard): | 84.985-85.035 mm (3.3459-3.3478 in) | |
| Piston pin outer diameter: | 20.993-20.998 mm (0.8265-0.8267 in) | |
| Piston ring side clearance: | Top | 0.040-0.073 mm (0.0016-0.0029 in) |
| Second | 0.030-0.070 mm (0.0012-0.0028 in) | |
| Piston ring end gap: | Top | 0.25-0.40 mm (0.0098-0.0157 in) |
| Second | 0.30-0.50 mm (0.0118-0.0197 in) | |
| Oil | 0.30-0.90 mm (0.012-0.035 in) | |
| Connecting rod center distance: | 146.00 mm (5.75 in) | |
| Crankshaft journal diameter: | 59.942-59.955 mm (2.3599-2.3604 in) | |
| Crankpin diameter: | 49.961-49.974 mm (1.9670-1.9675 in) | |
| Crankshaft center distance: | 43.00 mm (1.6929 in) | |
Cylinder head
The cylinder head is made of light and strong aluminum alloy with good cooling efficiency; it contains wedge-type combustion chambers. A special aluminum bronze valve seat is used on the intake valve, while a heat resistant steel valve seat is installed on the exhaust valve. These parts are all hot press-fitted.
The camshaft is made of special cast iron and located inside the rocker cover. Four aluminum alloy brackets support camshaft. Camshaft bearings are lubricated from oil holes which lead to the main oil gallery of the cylinder head. Concentric passages are drilled in the front and rear parts of the camshaft.
The valve system has a pivot type rocker arm that is activated directly by the cam mechanism. The Nissan L20B motor use the dual-type valve springs. Intake valves are 42 mm (1.65 in) in diameter and the exhaust valves are 35 mm (1.37 in). The intake valve duration is 248°, valve lift is 10.0 mm (0.39 in); the exhaust valve duration is 248°, valve lift is 10.5 mm (0.41 in).
The camshaft is driven by a double row roller chain driven by the crankshaft. The tension of the chain is controlled by a chain tensioner which is operated by spring and oil pressure.
The intake manifold is made of cast aluminum alloy and the exhaust manifold is made of cast iron.
| Cylinder head | ||
| Valve Arrangement: | OHV, chain drive | |
| Valves: | 8 (2 valves per cylinder) | |
| Intake/Exhaust duration: | 248°/248° | |
| Valve head diameter: | INTAKE | 42.0 mm (1.6535 in) |
| EXHAUST | 35.0 mm (1.3780 in) | |
| Valve length: | INTAKE | 114.9-115.2 mm (4.524-4.535 in) |
| EXHAUST | 115.7-116.0 mm (4.555-4.567 in) | |
| Valve stem diameter: | INTAKE | 7.965-7.980 mm (0.3136-0.3142 in) |
| EXHAUST | 7.945-7.960 mm (0.3128-0.3134 in) | |
| Valve spring free length: | INTAKE |
Outer: 49.98 mm (1.968 in) Inner: 44.85 mm (1.766 in) |
| EXHAUST |
Outer: 49.98 mm (1.968 in) Inner: 44.85 mm (1.766 in) |
|
| Valve lift: | INTAKE | 10.5 mm (0.413 in) |
| EXHAUST | 10.5 mm (0.413 in) | |
| Camshaft robe lift: | INTAKE | 7.00 mm (0.2753 in) |
| EXHAUST | 7.00 mm (0.2753 in) | |
| Outer camshaft journal diameter: | 47.949-47.962 mm (1.8878-1.8883 in) | |
Tightening torque specs
| Tightening torque specs | |
| Cylinder head bolt | 60-85 Nm; 6.5-8.5 kg·m; 47.0-61.5 ft·lb |
| Connecting rod big end nuts | 44-54 Nm; 4.5-5.5 kg·m; 33-40 ft·lb |
| Flywheel bolt | 137-157 Nm; 14.0-16.0 kg·m; 101-116 ft·lb |
| Main bearing cap bolt | 44-54 Nm; 4.5-5.5 kg·m; 33-40 ft·lb |
| Camshaft sprocket bolt | 118-157 Nm; 12.0-16.0 kg·m; 87-116 ft·lb |
| Oil pan bolts | 6-9 Nm; 0.6-0.0 kg·m; 4.3-6.5 ft·lb |
| Oil pump bolt | 11-15 Nm; 1.1-1.5 kg·m; 8-11 ft·lb |
| Oil pan drain plug | 20-30 Nm; 2.0-3.0 kg·m; 14-22 ft·lb |
| Rocker pivot lock nut | 49-59 Nm; 5.0-6.0 kg·m; 36-44 ft·lb |
| Camshaft locating plate bolts | 6-9 Nm; 0.6-0.9 kg·m; 4.3-6.5 ft·lb |
| Manifold nuts | 8-12 Nm; 0.8-1.2 kg·m; 5.8-8.7 ft·lb |
| Fuel pump nuts | 12-18 Nm; 1.2-1.8 kg·m; 8.7-13.0 ft·lb |
| Crank pulley nut | 118-157 Nm; 12.0-16.0 kg·m; 87-116 ft·lb |
Maintenance data
| Valve clearance (HOT) | |
| Intake valve | 0.25 mm (0.010 in) |
| Intake valve | 0.30 mm (0.012 in) |
| Valve clearance (COLD) | |
| Intake valve | 0.20 mm (0.008 in) |
| Exhaust valve | 0.25 mm (0.010 in) |
| Compression pressure | |
| Standard | 12.0 kg/cm2 (11.77 bar, 171 psi) / 350 rpm |
| Minimun | 9.0 kg/cm2 (8.83 bar, 128 psi) / 250 rpm |
| Oil system | |
| Oil consumption , L/1000 km (qt. per miles) | up to 0.5 (1 qt. per 1200 miles) |
| Recommended engine oil |
5W-30 5W-40 10W-30 10W-40 |
| Oil type API | SE |
| Engine oil capacity (Refill capacity) |
With oil filter: 4.4 l Without oil filter: 3.9 l |
| Oil change interval, km (miles) | 12,000 (7,500) |
| Oil pressure, kg/cm2 (psi) | 3.5-4.2 (49.8-56.9) at 2,000 rpm |
| Ignition system | |
| Spark plug |
USA models: BP6ES-11 (NGK), L45PW-11 (Hitachi) Canada models: BPR6ES (NGK) |
| Spark plug gap |
USA models: 1.0-1.1 mm (0.039-0.043 in) Canada models: 0.8-0.9 mm (0.03-0.035 in) |
| Spark plug tightening torque | 15-25 Nm; 1.5-2.5 kg·m; 11-15 ft·lb |
Vehicle applications
| Model | Years Produced |
| Datsun 610 | 1974–1976 |
| Datsun 710 | 1975–1977 |
| Datsun 620 | 1975–1979 |
| Datsun 200SX (S10) | 1975–1979 |
| Datsun 200B | 1977–1981 |
| Datsun 510 | 1978–1981 |
| Datsun 720 | 1979.5–1980 |
Author:
what is the pattern for tightening the head bolts
Use a torque wrench and begin tightening in the middle and working outwards to front and back like below:
RAD
7…8 P
3…4 L
1…2 U
5…6 G
9..10 S
Hi, where can I buy a cam for my 1980 Datsun L20 B motor. My engine original camshaft is broken. I live in Los Angeles, ca. Thanks