Nissan L26

Nissan L26 engineThe Nissan (Datsun) L26 / L26T is a 2.6 liter (2,565 cc, 156.5 cu-in) straight-six, four-stroke cycle natural aspirated gasoline engine from Nissan L-family. It was produced from 1973 through 1978. In 1975, the L26 engine replaced the Prince G-20.

The Nissan-Datsun L26 engine features a cast-iron block, a wedge-shaped combustion chamber, aluminum head with overhead camshaft and a fully balanced 7-bearing crankshaft and. The cylinder block is cast in a single unit and features deep skirting. The L26 is equipped with a single, two-barrel, downdraft carburetor. The SU twin carburetor provides a proper air-fuel mixture for the L26T engine.

The L26 with single carburetor has a compression ratio rating of 8.6:1, the L26T with SU twin-carb 8.3:1. Cylinder bore and piston stroke are 83.0 mm (3.27 in) and 79.0 mm (3.11 in), respectively. The L26 produced 140 PS (138 HP, 103 kW) of horsepower and 216 Nm (22.0 kg⋅m; 159 ft-lb) of torque. The L26T produced from 126 PS (124 HP, 92 kW) to 164 PS (162 HP, 121 kW) and from 186 Nm (19.9 kg⋅m; 137 ft-lb) to 215 Nm (21.9 kg⋅m; 158 ft-lb).

The breakdown of the engine code is as follows:

  • L – Engine Family
  • 26 – 2.6 Liter Displacement

General information

Engine Specifications
Engine code L26 / L26T
Layout Four stroke, Inline-6 (Straight-6)
Fuel type Gasoline
Production 1973-1978
Displacement 2.6 L, 2,565 cm3 (156.5 cu in)
Fuel system Single carburetor
Power adder None
Max. horsepower Nissan L26:
140 PS (138 HP, 103 kW) at 5,200 rpm
Nissan L26T:
150 PS (148 HP, 110 kW) at 5,600 rpm
164 PS (164 HP, 121 kW) at 5,600 rpm
162 PS (160 HP, 119 kW) at 5,600 rpm
141 PS (139 HP, 104 kW)
126 PS (124 HP, 92 kW)
Max. torque Nissan L26:
216 Nm (22.0 kg⋅m; 159 ft-lb) at 4,000 rpm
Nissan L26T:
215 Nm (21.9 kg⋅m; 158 ft-lb)
209 Nm (21.3 kg⋅m; 154 ft-lb)
206 Nm (21.0 kg⋅m; 152 ft-lb)
186 Nm (18.9 kg⋅m; 137 ft-lb)
189 Nm (19.3 kg⋅m; 139 ft-lb)
Firing order 1-5-3-6-2-4
Dimensions (L x H x W):

Cylinder block

The L26 engine has a cast-iron cylinder block, bore is 83.0 mm (3.27 in) and stroke is 79.0 mm (3.11 in). The cylinder block, a monoblock specially cast structure, employs the seven bearing support system for quietness and higher durability. The pistons are special aluminum casting with struts to control thermal expansion and have two compression rings and one combined oil ring.

The crankshaft of Nissan/Datsun L26 engine is fabricated of special forged steel. Provided with a high capacity balance weight. Light-weight pistons are of cast aluminum slipper-skirt type with invar-strut. The piston pin is of a special hollow type and is connected to the piston in a full-floating fit, and is press-fitted into the connecting rods.

The connecting rods are made of special forged steel. Connecting rod center distance is 130.35 mm (5.132 in).

Cylinder block
Cylinder block alloy Cast iron
Compression ratio: Single carb: 8.6:1
Twin carb: 8.3:1
Cylinder bore: 83.0 mm (3.27 in)
Piston stroke: 79.0 mm (3.11 in)
Number of piston rings (compression / oil): 2 / 1
Number of main bearings: 7
Cylinder inner diameter (standard): 83.000-83.050 mm (3.2677-3.2696 in)
Piston skirt diameter (standard): 82.985-83.035 mm (3.2671-3.2691 in)
Piston pin outer diameter: 20.993-20.998 mm (0.8265-0.8267 in)
Piston ring side clearance: Top 0.045-0.080 mm (0.0018-0.0031 in)
Second 0.030-0.070 mm (0.0012-0.0028 in)
Piston ring end gap: Top 0.23-0.38 mm (0.0091-0.0150 in)
Second 0.15-0.30 mm (0.0059-0.0118 in)
Oil 0.15-0.30 mm (0.0059-0.0118 in)
Piston ring height: Top 1.977 mm (0.0778 in)
Second 1.977 mm (0.0778 in)
Connecting rod center distance: 130.35 mm (5.132 in)
Crankshaft journal diameter: 54.942-54.955 mm (2.1631-2.1336 in)
Crankpin diameter: 49.961-49.974 mm (1.9670-1.9675 in)
Crankshaft center distance: 39.5 mm (1.551 in)

Cylinder head

The cylinder head is made of a light, strong aluminum alloy with good cooling efficiency. The camshaft is made of specially cast iron and is located inside the rocker cover. The L26/L26T has the intake valves with a head diameter of 42.0 mm (1.65 in) and the exhaust valves with a head diameter of 35.0 mm (1.37 in).

The valve system has a pivot type rocker arm that is activated directly by the cam mechanism. The Nissan L26 motor use the dual-type valve springs. 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 cast aluminum and the exhaust manifold is cast iron.

Cylinder head
Cylinder head alloy: Aluminum
Valve Arrangement: OHV, chain drive
Valves: 12 (2 valves per cylinder)
Intake duration: L26: 240°
L26T: 248°
Exhaust duration: L26: 248°
L26T: 248°
Valve head diameter: INTAKE 42.0 mm (1.65 in)
EXHAUST 35.0 mm (1.3779 in)
Valve length: INTAKE 114.9-115.2 (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: OUTER 49.98 mm (1.968 in)
INNER 44.85 mm (1.766 in)
Valve lift: INTAKE 11.0 mm (1.968 in)
EXHAUST 11.0 mm (1.968 in)
Outer camshaft journal diameter: 47.949-47.962 mm (1.8878-1.8883 in)

Tightening torque specs

Tightening torque specs
Cylinder head bolt Step 1: 40 Nm; 4.0 kg·m; 28 ft·lb
Step 2: 60 Nm; 6.0 kg·m; 43 ft·lb
Step 3: 73-83 Nm; 7.5-8.5 kg·m; 54-61 ft·lb
Connecting rod big end nut 37-44 Nm; 3.7-4.3 kg·m; 27-31 ft·lb
Flywheel bolt 127-146 Nm; 13.0-15.0 kg·m; 94-108 ft·lb
Camshaft sprocket bolt 127-147 Nm; 13.0-15.0 kg·m; 94-108 ft·lb
Main bearing cap bolt 44-54 Nm; 4.5-5.5 kg·m; 33-40 ft·lb
Crank pulley bolt 127-147 Nm; 13.0-15.0 kg·m; 94-108 ft·lb
Rocker pivot lock nut 49-59 Nm; 5.0-6.0 kg·m; 36-46 ft·lb

Maintenance data

Valve clearance (HOT)
Intake valve 0.25 mm (0.010 in)
Exhaust 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
Oil type API SE
Engine oil capacity (Refill capacity) Without oil filter: 4.0 l (1-1/8 US gal)
With oil filter: 4.7 l (1-1/4 US gal)
Oil change interval, km (miles) 5,000-10,000 (3,000-6,000)
Ignition system
Spark plug Cold: BP7ES, L44PW, BPR7ES
Standard: BP6ES, L45PW, BPR6ES
Spark plug gap 0.8-0.9 mm (0.03 -0.035 in)

Vehicle applications

Model Years Produced
Nissan Cedric (230) 1972–1975
Datsun 260C
Nissan Laurel (C130) 1974–1977
Datsun 260Z 1974–1978
Nissan Cedric (330) 1976–1978
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