Subaru EA71 Specifications
| Engine Model: Subaru EA71 |
| Engine Type: 4-cycle 4-cylinder OHV 8-valve air-cooled or liquid-cooled gasoline |
| Total Displacement: 97.3 cu.in (1.59 L) |
| Rated Engine Power: 70-77 Hp (52-57 kW) at 5200 rpm |
| Fuel System Type: Single or two-barrel downdraft carburetor |
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The Subaru EA71 is a 1.6-liter, 4-cylinder
horizontally-opposed (flat-four or "boxer"), overhead valve (OHV),
8-valve, naturally aspirated gasoline engine. It is a member of Subaru's
foundational EA series, which established the brand's enduring
commitment to the boxer engine layout. Introduced in the early 1970s,
the EA71 served as a larger-displacement, more powerful evolution of the
earlier EA53 and EA63 engines. Its design prioritizes compact packaging,
a low center of gravity, and inherent smoothness due to the
opposed-piston layout, which naturally cancels out primary vibrations.
Featuring a cast-iron block, aluminum alloy cylinder heads, and a single
downdraft carburetor, the EA71 is a study in simple, robust engineering.
It is renowned for its durability, ease of maintenance, and distinctive
smooth, off-beat exhaust note. While not powerful by modern standards,
it delivers adequate torque for its era and is famously tolerant of
neglect, often achieving remarkably high mileage. This engine powered a
generation of Subaru's core vehicles, solidifying the brand's reputation
for rugged, dependable transportation and laying the groundwork for all
future Subaru flat engines.
Engine Family / Model: Subaru EA series, Model EA71.
Engine Type: Horizontally-opposed four-cylinder (flat-four, boxer),
longitudinally front-mounted, four-stroke cycle, air-cooled or
water-cooled (depending on specific application and year), naturally
aspirated gasoline engine.
Fuel Management: Single downdraft carburetor (Hitachi or Aisan). Later
fuel-injected versions exist but are extremely rare. Aspiration:
Naturally aspirated.
Bore: 92.0 mm / 3.622 inches.
Stroke: 60.0 mm / 2.362 inches.
Displacement: 1,595 cc / 97.3 cubic inches.
Compression Ratio: Varies by year and market: Typically 8.5 : 1 for
regular fuel. Some high-compression versions reached 9.0 : 1. Firing
Order: 1-3-2-4. (Cylinders numbered: Left bank: 1-2; Right bank: 3-4.
Front cylinders are 1 and 3).
Rotation Direction (from front/crank pulley): Clockwise.
Maximum Power Output (JIS Gross): 52-57 kW (70-77 Hp) at 5,200 rpm.
Maximum Torque: 115-120 Nm (85-89 lb-ft) at 3,200 rpm. Redline:
5,800-6,000 rpm.
Fuel Requirement: Regular leaded gasoline (original). Can run on
unleaded with hardened valve seats (later models) or additive. Emissions
Compliance: Pre-catalytic converter, simple emission controls.
Construction: Cast iron, split horizontally at the crankshaft centerline
(a "split-case" or "block-and-cradle" design). The lower section
(cradle) contains the main bearing saddles. This design allows the
crankshaft to be installed from below.
Cylinder Bores: Integral (parent bore) in the upper cast iron block
halves.
Crankshaft: Cast nodular iron, supported by three main bearings. The
boxer layout requires a specific crankshaft with crankpins shared by
opposing pistons (180-degree offset).
Main Bearings: Steel-backed, babbitt (white metal) shell bearings.
Case Halves Sealing: Uses a large, complex paper gasket or silicone
sealant between the upper and lower case halves. Sealing integrity is
critical.
Construction: aluminum alloy, one per bank. Each head is a simple, flat
design.
Valve Arrangement: Overhead Valves (OHV), actuated by pushrods and
rocker arms. The camshaft is located centrally in the block, above the
crankshaft.
Valvetrain: Single camshaft, gear-driven from the crankshaft. Pushrods
operate rocker arms within the cylinder head. Combustion Chamber:
Wedge-type or simple bathtub design within the head.
Valve Seat Angle: 45 deg.
Valve Diameter: Intake: 38.0 mm (1.496 inches). Exhaust: 33.0 mm (1.299
inches).
Valve Clearance (Cold): Adjustable via screw and locknut on the rocker
arms. Clearance: Intake: 0.20 mm (0.008 inches). Exhaust: 0.25 mm (0.010
inches). Regular adjustment is a key maintenance item.
Camshaft Drive: Straight-cut spur gears, resulting in a characteristic
mechanical whine.
Carburetor: Single, two-barrel downdraft carburetor (e.g., Hitachi
DCG306-38). Mounted centrally on a cast aluminum intake manifold that
feeds both cylinder banks.
Choke: Manual choke (early) or automatic choke (later).
Fuel Pump: Mechanical diaphragm-type fuel pump, driven by an eccentric
lobe on the camshaft.
Air Filter: Oil-bath type air cleaner (early) or later paper element
housed in a metal canister.
Fuel Lines: Standard steel hard lines and rubber flex lines.
Fuel-injected "EA71i" variants exist (e.g., in some Leone MPFI models),
utilizing a primitive multi-point injection system, but these are
uncommon outside specific markets.
Type: Full-pressure, force-fed wet-sump system with a gear-type pump.
Oil Pump: External gear-type, driven from the crankshaft (often via a
hexagon drive).
Oil Filter: Canister-type with a replaceable paper element (early) or
spin-on full-flow cartridge (later).
Oil Cooler: Not equipped. Oil Capacity (including filter): 4.0 liters
(4.2 US quarts / 3.5 Imperial quarts).
Recommended Oil Grade: API SB/SC or later. Viscosity: SAE 10W-30 or
10W-40 mineral oil. Straight-weight oils like SAE 30 were commonly used.
Operating Oil Pressure: At operating temperature: 275-415 kPa (2.8-4.2
kgf/cm2 / 40-60 psi) at 2,000 rpm. Idle pressure can be as low as 69 kPa
(0.7 kgf/cm2 / 10 psi).
Two Distinct Types: Air-Cooled (Early, pre-1977): Uses an external
belt-driven cooling fan and shrouding. Cooling fins are cast into the
cylinder heads and barrels. Thermostatically controlled flaps direct
airflow. Oil cooling is critical for managing engine temperature.
Water-Cooled (Later, post-1977): Pressurized, forced circulation system
with a front-mounted radiator, belt-driven water pump, and thermostat.
The water pump is driven by the timing belt (on OHV models, this belt
only drives the water pump and possibly an alternator, not camshaft
timing).
Thermostat: Wax pellet type. Opening temperature is 82°C (180°F).
Radiator Pressure Cap: 88-108 kPa (0.9-1.1 kgf/cm2 / 13-16 psi).
Coolant Capacity: 6.0 liters (6.3 US quarts / 5.3 Imperial quarts) for
water-cooled versions.
Electrical System: 12-volt DC, negative ground (some very early may have
been positive ground).
Ignition System: Conventional breaker-point ignition system with a
distributor, coil, condenser, and spark plug wires. Later models (early
80s) may have electronic ignition.
Distributor: Driven by a gear from the camshaft. Contains mechanical and
vacuum advance mechanisms. Spark Plugs: Standard copper core, 14mm
thread. Gap: 0.7-0.8 mm (0.028-0.031 inches). Emission Controls:
Minimal. May include a Positive Crankcase Ventilation (PCV) system and
ported vacuum for distributor advance. No catalytic converter on most
applications.
Clutch and Transmission: Engine is integral with the transaxle in a
"unitized" powertrain, a Subaru hallmark. The clutch is a single dry
plate.
Length (from front of crank pulley to rear of bellhousing): 600 mm (23.6
inches).
Width (over cylinder heads): 800 mm (31.5 inches)-the defining wide
profile of the boxer.
Height (from bottom of sump to top of carburetor): 550 mm (21.7 inches).
Very low profile.
Dry Weight (engine only, long block): 125-135 kg (276-298 lbs).
Engine Oil and Filter Change Interval: Every 5,000 km (3,100 miles) or 6
months. Frequent changes are key to longevity, especially in air-cooled
versions. Spark Plugs and Points: Replace spark plugs every 10,000 km
(6,200 miles). Points, condenser, and rotor should be replaced and
timing set every 10,000-20,000 km. Valve Clearance Adjustment: Check and
adjust every 10,000-20,000 km (6,200-12,400 miles). Critical for
performance and preventing burnt valves. Carburetor Adjustment:
Synchronization and mixture adjustment should be performed periodically.
Timing Belt (Water-Cooled OHV): The belt drives only the water pump (and
sometimes alternator). Replace every 60,000 km (37,000 miles) or 5 years
to prevent overheating from pump failure. This is not a
timing/interference belt for valves. Cooling System (Water-Cooled):
Flush and refill coolant every 2 years. Check fan belt tension. Air
Filter (Oil-Bath): Clean and refill with fresh oil every service
interval. Distributor Cap and Wires: Inspect for cracks and corrosion.
Replace wires every 40,000 km (25,000 miles).
Cylinder Head Bolts: Multi-stage, in specific sequence. Step 1: 20 Nm
(15 lb-ft). Step 2: 40 Nm (30 lb-ft). Step 3: Final torque to 55-60 Nm
(41-44 lb-ft). Always follow the factory sequence from center outwards
on each head.
Main Bearing Cap Bolts: 40-45 Nm (30-33 lb-ft).
Connecting Rod Cap Bolts: 30-35 Nm (22-26 lb-ft).
Flywheel to Crankshaft Bolts: 60-70 Nm (44-52 lb-ft).
Crankshaft Pulley Bolt: 110-120 Nm (81-89 lb-ft).
Camshaft Gear Bolt: 70-80 Nm (52-59 lb-ft).
Spark Plugs: 25-30 Nm (18-22 lb-ft).
Oil Pan Bolts: 8-10 Nm (6-7 lb-ft).
Rocker Cover Bolts: 5-7 Nm (3.7-5.2 lb-ft).
Intake Manifold Nuts: 18-22 Nm (13-16 lb-ft).
Exhaust Manifold Nuts: 25-30 Nm (18-22 lb-ft).
Case Halves Bolts: Varies by size; typically 20-25 Nm (15-18 lb-ft) for
larger bolts. Critical to follow sequence to avoid leaks.
The Subaru EA71 engine was the workhorse of Subaru's lineup throughout
the 1970s and into the early 1980s: Subaru Leone (First Generation,
1971-1979): The primary application, powering sedan, coupe, and station
wagon variants globally (known as the Leone, 1600, or GL/DL). Subaru
BRAT (1978-1981): The iconic Bi-drive Recreational All-terrain
Transporter (BRAT) was initially powered by the EA71. Subaru 4WD Station
Wagons/Vans (e.g., Touring Wagon): Used in various early Subaru estate
and utility vehicles.
Subaru FF-1 G (1970-1972): The final years of the FF-1 series used a
version of the EA71. Violet (Export markets): Badge-engineered versions
of the Leone. The EA71 was succeeded by the overhead cam (OHC) EA81 and
then the EJ series. Its use spanned the transition from air-cooling to
water-cooling and from simple carburetion to early electronic fuel
injection, making it a transitional yet foundational engine in Subaru's
history.
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