Nissan L18T

Nissan L18T SU Twin carbThe Nissan / Datsun L18T is a carbureted 1.8 liter (1,770 cc, 108.01 cu in) straight-4, four-stroke cycle gasoline engine from Nissan L-family. The L18T engine was basically the same as the L18 but had twin SU carburetor.

The Nissan-Datsun L18T engine feature OHC valves, wedge-shaped combustion chamber, aluminum cylinder head and fully balanced five-bearing crankshaft to turn out smooth, dependable power. The L18T engine uses eight balance weights. The cylinder block is cast in a single unit, featuring deep skirting. To provide air-fuel mixing the L18T used SU type carburetor.

The L18T engine has an 85.0 mm (3.35 in) cylinder bore and 78.0 mm (3.07 in) piston stroke with a compression ratio of 9.5:1. It produced 110 PS (109 HP, 81 kW) at 6,000 rpm and 152 Nm (15.5 kg·m, 112 lb·ft) at 3,600 rpm.

The breakdown of the engine code is as follows:

  • L – Engine Family
  • 18 – 1.6 Liter Displacement
  • T – Twin carburetor

General information

Engine Specifications
Engine codeL18T
LayoutFour stroke, Inline-4 (Straight-4)
Fuel typeGasoline
Displacement1.8 L, 1,770 cm3 (108.01 cu in)
Fuel systemTwin SU carb
Power adderNone
Max. horsepower 110 PS (109 HP, 81 kW) at 6,000 rpm
Max. torque 152 Nm (15.5 kg·m, 112 lb·ft) at 3,600 rpm
Firing order1-3-4-2
Dimensions (L x H x W):

Cylinder block

The Nissan (Datsun) L18T motor has a cast-iron cylinder block. The cylinder block, which is of a monoblock special casting structure, adopts the 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 L18T engine cylinder bore is 85.0 mm (3.35 in) and the piston stroke is 78.0 mm (3.07 in), compression ratio rating is 9.5:1.

The crankshaft is a special steel forging. Fully balanced, it turns out smooth, dependable power at high speed. Main bearings gain lubrication from oil pumped through the main oil gallery and the oil holes which run in parallel with cylinder bores.

The pistons are special aluminum casting with struts to control thermal expansion and have two compression rings and one combined oil ring. The L18T use slightly dished pistons. 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 alloyCast iron
Compression ratio:9.5:1
Cylinder bore:85.0 mm (3.35 in)
Piston stroke:78.0 mm (3.07 in)
Number of piston rings (compression / oil):2 / 1
Number of main bearings:5
Cylinder inner diameter (standard):85.000 mm (3.346 in)
Piston skirt diameter (standard):84.985-85.035 mm (3.3459-3.3478 in)
Piston pin outer diameter:20.995-21.000 mm (0.8266-0.8268 in)
Piston ring side clearance:Top0.085-0.080 mm (0.0018-0.0031 in)
Second0.030-0.070 mm (0.0012-0.0028 in)
Piston ring end gap:Top0.35-0.55 mm (0.0014-0.022 in)
Second0.30-0.50 mm (0.012-0.020 in)
Oil0.30-0.90 mm (0.012-0.035 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:39.00 mm (1.5354 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 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. The valve system has a pivot type rocker arm that is activated directly by the cam mechanism. The Nissan L18T motor use the dual-type valve springs.

The valves head diameter is the same as the L18 engine, but duration and valve lift are different. The intake valves are 42.0 mm (1.65 in) in diameter and the exhaust valves are 35.0 mm (1.37 in). The intake valve duration is 248°, valve lift is 10.5 mm (0.41 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 casted aluminum alloy. The twin-carburetor type L18 engines use the one with an independent design for each carburetor.

Cylinder head
Valve Arrangement:OHV, chain drive
Valves:8 (2 valves per cylinder)
Intake/Exhaust duration:248°/248°
Valve head diameter:INTAKE42.0 mm (1.6535 in)
EXHAUST35 mm (1.37 in)
Valve length:INTAKE114.9-115.2 mm (4.524-4.535 in)
EXHAUST115.7-116.0 mm (4.555-4.567 in)
Valve stem diameter:INTAKE7.965-7.980 mm (0.3136-0.3142 in)
EXHAUST7.945-7.960 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)
Camshaft robe lift:INTAKE7.00 mm (0.2753 in)
EXHAUST7.00 mm (0.2753 in)
Rocker arm lever ratio:1.45
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; 28.9 ft·lb
Step 2: 60 Nm; 6.0 kg·m; 43.4 ft·lb
Step 3: 60-85 Nm; 6.5-8.5 kg·m; 47.0-61.5 ft·lb
Connecting rod big end nuts31-37 Nm; 3.2-3.8 kg·m; 23-27 ft·lb
Flywheel bolt137-157 Nm; 14.0-16.0 kg·m; 101-116 ft·lb
Main bearing cap bolt44-54 Nm; 4.5-5.5 kg·m; 33-40 ft·lb
Camshaft sprocket bolt118-157 Nm; 12.0-16.0 kg·m; 87-116 ft·lb
Oil pan bolts6-9 Nm; 0.6-0.0 kg·m; 4.3-6.5 ft·lb
Oil pump bolt11-15 Nm; 1.1-1.5 kg·m; 8-11 ft·lb
Oil pan drain plug20-30 Nm; 2.0-3.0 kg·m; 14-22 ft·lb
Rocker pivot lock nut49-59 Nm; 5.0-6.0 kg·m; 36-44 ft·lb
Camshaft locating plate bolts6-9 Nm; 0.6-0.0 kg·m; 4.3-6.5 ft·lb
Manifold nuts8-12 Nm; 0.8-1.2 kg·m; 5.8-8.7 ft·lb
Fuel pump nuts12-18 Nm; 1.2-1.8 kg·m; 8.7-13.0 ft·lb
Crank pulley nut118-157 Nm; 12.0-16.0 kg·m; 87-116 ft·lb

Maintenance data

Valve clearance (HOT)
Intake valve0.25 mm (0.010 in)
Intake valve0.30 mm (0.012 in)
Valve clearance (COLD)
Intake valve0.20 mm (0.008 in)
Exhaust valve0.25 mm (0.010 in)
Compression pressure
Standard12.0 kg/cm2 (11.77 bar, 171 psi) / 350 rpm
Minimun9.0 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 APISE
Engine oil capacity (Refill capacity) Hight level: 4.3 l
Low level: 3.3 l
Oil change interval, km (miles)5,000-10,000 (3,000-6,000)
Oil pressure, kg/cm2 (psi)3.5-4.2 (49.8-56.9) at 2,000 rpm
Ignition system
Spark plugBP6ES (NGK)
Spark plug gap0.8-0.9 mm (0.03-0.035 in)
Spark plug tightening torque15-25 Nm; 1.5-2.5 kg·m; 11-15 ft·lb
Carburetor modelHJL38W6
Bore38 mm (1.4961 in)
Piston lift29 mm (1.1417 in)
Jet needleM-76
Nozzle jet diameter2.34 mm (0.0921)
Suction spring#23
Float level23 mm (0.9055 in)
Float ventingInner vent type
Fuel pressure0.24 kg·cm3 (3.41 lb·sq in)
Throttle clearance at full throttle0.6 mm (0.0236 in)
Position at full throttle6.5°

Vehicle applications

ModelYears Produced
Nissan Bluebird 180B SSS (610)
Nissan Bluebird 1.8 GL coupé (910)
Nissan Bluebird SSS Hardtop Coupé (910)
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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1 Comment

  1. I have SU carbs standard on my 1979 Stanza SSS, would like to know if you have anything on how to set these carbs

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