Isuzu G180 Specifications
| Engine Model: Isuzu G180 |
| Engine Type: 4-stroke in-line 4-cylinder 8-valve SOHC liquid-cooled gasoline |
| Total Displacement: 110.8 cu.in (1.82 L) |
| Rated Engine Power: 80-100 Hp (60-75 kW) at 5400 rpm |
| Fuel System Type: Carburetor |
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The Isuzu G180 is a 1.8-liter inline 4-cylinder
gasoline engine produced by Isuzu Motors during the 1970s and 1980s.
This power unit belongs to the Isuzu G-family of engines, a lineage
known for its robust cast iron construction and overhead camshaft
architecture. The G180 was engineered for a dual role: providing
reliable service in light commercial vehicles and delivering responsive
performance in passenger cars. Its design emphasizes mechanical
simplicity, with a timing chain-driven camshaft and a cross-flow
cylinder head that improves volumetric efficiency.
The Isuzu G180 is a water-cooled, 4-stroke, inline 4-cylinder gasoline
engine featuring a single overhead camshaft (SOHC) with 2 valves per
cylinder, totaling 8 valves. The engine operates on a carbureted fuel
system, most commonly a Hitachi progressive two-barrel unit. It employs
a cast iron cylinder block and an aluminum alloy cross-flow cylinder
head to balance durability with effective heat dissipation.
The valvetrain is driven by a timing chain, a design choice that
contributes to the engine’s extended service life. Ignition is provided
by a distributor-based system; later North American variants for the
Chevrolet LUV received a High Energy Ignition (HEI) system for improved
cold-start reliability and reduced maintenance.
Engine Type: 4-cycle, water-cooled, inline 4-cylinder, SOHC gasoline
Displacement: 1817 cc (110.8 cu.in)
Bore: 84.0 mm (3.31 in)
Stroke: 82.0 mm (3.23 in)
Compression Ratio: 8.5:1 (standard)
Compression Ratio: 8.7:1 (high output variants)
Power Output: 80-100 hp (60-75 kW) at 5400 rpm
Peak Torque: 135 Nm to 145 Nm (100 lb-ft to 107 lb-ft) at 3000-3400 rpm
Firing Order: 1-3-4-2
Valvetrain: SOHC, 8 valves (2 per cylinder)
Camshaft Drive: Timing chain
Fuel System: Carburetor (Hitachi two-barrel on most applications)
Ignition System: Distributor with contact breaker points or HEI
Ignition Timing: 6° BTDC at 800 rpm idle
Spark Plug Type: NGK BP6ES
Spark Plug Gap: 0.7 mm to 0.8 mm (0.028 in to 0.031 in)
The cylinder block is manufactured from gray cast iron, a material
selected for its structural rigidity, wear resistance, and capacity to
dampen mechanical noise. The block is a monobloc design with siamesed
cylinder bores, meaning no coolant passages exist between adjacent
cylinders. This arrangement increases block stiffness and reduces bore
distortion under thermal loading. The cylinder bores are machined
directly into the cast iron parent material without replaceable liners.
The block incorporates a deep-skirt design, extending the side walls
below the crankshaft centerline to enhance support for the main bearing
caps. Five main bearings support the crankshaft, with the thrust washer
located at the center main bearing (No. 3). Oil galleries are drilled
longitudinally through the block on the camshaft side, feeding the main
bearings and the camshaft journals.
The cylinder head is a single casting made from aluminum alloy, a choice
that reduces overall engine mass and promotes rapid heat transfer away
from the combustion chambers. The head features a cross-flow port
configuration: intake ports on one side, exhaust ports on the opposite
side. This design minimizes heat transfer from the exhaust manifold to
the incoming air-fuel charge and improves scavenging efficiency.
The combustion chambers are hemispherical in shape. The SOHC operates 8
valves via rocker arms that pivot on a fixed shaft. Valve lash is
adjustable by means of threaded adjusters and locknuts on the rocker
arms. Intake valve diameter is 40.0 mm (1.57 in); exhaust valve diameter
is 34.0 mm (1.34 in). Valve stems measure 8.0 mm (0.315 in) in diameter.
Valve seats are pressed into the aluminum head and are manufactured from
a heat-resistant alloy.
The fuel system is carburetor-based, with the engine calibrated to
operate on a mechanical fuel pump mounted to the cylinder block. The
primary carburetor for G180 applications is the Hitachi two-barrel
progressive unit, designated model DCP 306 or similar. This carburetor
features a primary barrel for low-load operation and a secondary barrel
that opens progressively under high-demand conditions.
A mechanical accelerator pump provides enrichment during rapid throttle
opening. A choke mechanism, either manual or automatic (thermostatic
coil type), enriches the mixture for cold starts. The carburetor
incorporates an idle-cut solenoid to prevent engine run-on (dieseling)
after ignition shutoff. Fuel is drawn from the tank via a diaphragm-type
pump driven by an eccentric lobe on the camshaft.
The lubrication system is a fully pressurized, wet-sump design. A
gear-type oil pump is mounted internally within the front timing cover
and is driven directly by the crankshaft. The pump draws oil through a
strainer pickup tube submerged in the oil pan. Oil is then forced
through a full-flow spin-on filter mounted externally on the cylinder
block. A pressure relief valve integral to the pump body maintains
system pressure between 294 kPa and 392 kPa (43 psi to 57 psi) at
operating speed.
Oil galleries within the cylinder block deliver pressurized oil to the
main bearings, connecting rod bearings, and camshaft bearings. Rocker
arm shaft lubrication is supplied through a vertical passage from the
cylinder head gasket interface. The oil pan is constructed from stamped
steel and has a capacity of 4.0 L (4.2 qt) including the filter.
The cooling system is a pressurized, thermostatically controlled liquid
circuit. A belt-driven centrifugal water pump is mounted on the front of
the cylinder block. The pump circulates a mixture of ethylene glycol
coolant through the water jackets surrounding the cylinders and
combustion chambers. A wax-pellet thermostat is installed in the
thermostat housing at the coolant outlet on the cylinder head.
The thermostat begins to open at 82°C (180°F) and achieves full lift at
95°C (203°F). The system operates under a pressure cap rated at 69 kPa
to 103 kPa (10 psi to 15 psi), raising the boiling point of the coolant.
A radiator with vertical or cross-flow core dissipates heat to the
atmosphere. The engine-driven fan is mounted to the water pump hub.
Timing Drive: The camshaft is driven by a single-row roller chain
operating from a sprocket on the crankshaft. A nylon-faced or steel
timing chain tensioner takes up slack on the slack side of the chain. A
fixed guide or stationary chain guide is mounted on the opposite side.
No automatic hydraulic tensioner is used; adjustment requires manual
tensioner setup or periodic inspection.
Ignition System: Standard models use a contact breaker (points)
distributor driven by the camshaft. The distributor incorporates
centrifugal and vacuum advance mechanisms. Late North American Chevrolet
LUV variants received a High Energy Ignition (HEI) system with an
integrated ignition coil and magnetic pickup, eliminating the contact
breaker points. The HEI system provides increased spark energy and
reduced maintenance.
Exhaust System: A cast iron exhaust manifold collects gases from all
four cylinders into a single outlet. The manifold is bolted to the
cylinder head on the opposite side from the intake manifold.
Length: 610 mm (24.0 in) from fan face to flywheel housing.
Width: 550 mm (21.7 in) at maximum envelope (including exhaust
manifold).
Height: 640 mm (25.2 in) from oil pan rail to top of rocker cover.
Dry Weight (without fluids): 138 kg (304 lb).
Engine Oil Capacity (with filter): 4.0 L (4.2 qt).
Recommended Oil Grade: SAE 10W-30 or SAE 10W-40 for most climates.
Recommended Oil Grade: SAE 20W-50 for hot ambient conditions.
Coolant Capacity (engine and radiator): 7.5 L (7.9 qt).
Intake Valve Clearance (hot): 0.20 mm (0.008 in).
Exhaust Valve Clearance (hot): 0.25 mm (0.010 in).
Ignition Timing: 6° BTDC at 800 rpm with vacuum advance disconnected.
Spark Plug Gap: 0.7 mm to 0.8 mm (0.028 in to 0.031 in).
Idle Speed (manual transmission, neutral): 750 rpm to 800 rpm.
Idle Speed (automatic transmission, Drive engaged): 650 rpm to 700 rpm.
Curb Idle CO adjustment (carburetor): 1.0% to 2.0% volume.
Timing Chain Inspection Interval: Inspect for slack at 100,000 km
(62,000 mi).
Oil Change Interval: 5000 km (3100 mi) under normal service.
Cylinder Head Bolts, Stage 1: 30 Nm (22 lb-ft).
Cylinder Head Bolts, Stage 2: 60 Nm (44 lb-ft).
Cylinder Head Bolts, Stage 3: 90 Nm (66 lb-ft).
Main Bearing Cap Bolts: 70 Nm (52 lb-ft) for standard engines.
Main Bearing Cap Bolts: 80 Nm (59 lb-ft) for high output variants.
Connecting Rod Cap Bolts: 45 Nm (33 lb-ft).
Crankshaft Pulley Bolt (center): 110 Nm (81 lb-ft).
Flywheel to Crankshaft Bolts: 65 Nm (48 lb-ft).
Camshaft Sprocket Bolt: 50 Nm (37 lb-ft).
Camshaft Bearing Cap Bolts (on head): 20 Nm (15 lb-ft) for SOHC journal
caps.
Rocker Arm Shaft Bracket Bolts: 25 Nm (18 lb-ft).
Intake Manifold Bolts: 18 Nm (13 lb-ft).
Exhaust Manifold Nuts: 30 Nm (22 lb-ft).
Oil Pan Bolts: 10 Nm (7 lb-ft).
Spark Plugs: 20 Nm (15 lb-ft).
Oil Filter (spin-on): 12 Nm (9 lb-ft).
The Isuzu G180 engine was installed across a range of passenger cars and
light commercial vehicles produced by Isuzu and its licensees between
1972 and 1985.
Chevrolet LUV (1972-1982) - North American market pickup.
Isuzu Faster (KB series) - Global market pickup (1972-1984).
Isuzu Gemini (1975-1984) - Passenger sedan and coupe.
Isuzu 117 Coupe - Upmarket 2-door coupe (early 1970s).
Isuzu Florian - Mid-size sedan (late 1970s).
Isuzu Wasp - Pickup variant (selected Asian markets).
Bedford KB - United Kingdom and Commonwealth market pickup (rebadged
Isuzu Faster).
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