The 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 code | L18T |
| Layout | Four stroke, Inline-4 (Straight-4) |
| Fuel type | Gasoline |
| Production | – |
| Displacement | 1.8 L, 1,770 cm3 (108.01 cu in) |
| Fuel system | Twin SU carb |
| Power adder | None |
| 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 order | 1-3-4-2 |
| Dimensions (L x H x W): | – |
| Weight | – |
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 alloy | Cast 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: | Top | 0.085-0.080 mm (0.0018-0.0031 in) |
| Second | 0.030-0.070 mm (0.0012-0.0028 in) | |
| Piston ring end gap: | Top | 0.35-0.55 mm (0.0014-0.022 in) |
| Second | 0.30-0.50 mm (0.012-0.020 in) | |
| Oil | 0.30-0.90 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: | INTAKE | 42.0 mm (1.6535 in) |
| EXHAUST | 35 mm (1.37 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) |
|
| Camshaft robe lift: | INTAKE | 7.00 mm (0.2753 in) |
| EXHAUST | 7.00 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 nuts | 31-37 Nm; 3.2-3.8 kg·m; 23-27 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; 0.6-0.0 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) |
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 plug | BP6ES (NGK) |
| Spark plug gap | 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 |
| Carburetor | |
| Carburetor model | HJL38W6 |
| Bore | 38 mm (1.4961 in) |
| Piston lift | 29 mm (1.1417 in) |
| Jet needle | M-76 |
| Nozzle jet diameter | 2.34 mm (0.0921) |
| Suction spring | #23 |
| Float level | 23 mm (0.9055 in) |
| Float venting | Inner vent type |
| Fuel pressure | 0.24 kg·cm3 (3.41 lb·sq in) |
| Throttle clearance at full throttle | 0.6 mm (0.0236 in) |
| Position at full throttle | 6.5° |
Vehicle applications
| Model | Years Produced |
| Nissan Bluebird 180B SSS (610) | – |
| Nissan Bluebird 1.8 GL coupé (910) | – |
| Nissan Bluebird SSS Hardtop Coupé (910) | – |
Author:
I have SU carbs standard on my 1979 Stanza SSS, would like to know if you have anything on how to set these carbs