Nissan A12 Specifications
| Engine Model: Nissan A12 |
| Engine Type: 4-cycle inline 4-cylinder OHV liquid-cooled gasoline |
| Total Displacement: 71.4 cu.in (1.17 L) |
| Rated Engine Power: 60-72 Hp (45-54 kW) at 6000 rpm |
| Fuel System Type: Single-barrel or twin-barrel downdraft carburetor |
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The Nissan A12 engine is a 1.2-liter
inline-four gasoline engine belonging to the very successful Nissan
A-series engine family. Introduced in 1970 and continuing in production
in various forms through the 2000s, the A12 became one of Nissan’s most
enduring and reliable small engines. It powered numerous global models,
including the Datsun B110 (Sunny / 1200), B210, B310, Nissan Cherry, and
various vans and commercial vehicles. Known for its rugged simplicity,
low maintenance cost, easy rebuildability, and excellent fuel economy,
the A12 earned a reputation as one of the toughest small engines Nissan
ever built.
The A12 is designed around a cast-iron block and an aluminum cylinder
head with overhead valves (OHV). The simple pushrod valvetrain, robust
crankshaft, and gear-driven camshaft give the A12 exceptional
durability. Its carbureted fuel system, straightforward ignition layout,
and minimal emissions equipment in early models make it easy to service
and tune. Over time, the A12 appeared in multiple versions, including
the early A12 (1970–1973), the revised A12 (1974–1982), the A12A
variant, and late-production industrial versions.
Its compact size, strong low-rpm torque, and predictable drivability
made it highly successful not only for passenger cars but also for
agricultural machinery, forklifts, and generators. Today it remains
popular among classic Datsun enthusiasts for restoration, motorsport
use, and daily driving.
The A12 is a naturally aspirated inline-four, water-cooled, four-stroke
gasoline engine with a displacement of 1171 cc (71.4 cubic inches). Bore
is 73.0 mm (2.87 inches), and stroke is 70.0 mm (2.76 inches). This
undersquare configuration supports strong low-rpm torque and smooth
drivability.
Compression ratios vary by model and
market:
- Early A12: approx. 9.0:1
- Later A12: approx. 9.0:1–9.5:1
- A12A: approx. 9.0:1
Power output depends on carburetor type and
emissions tuning:
- Early A12 (B110): approx. 69–72 hp (51–54 kW) at ~6000 rpm
- Mid-series A12 (B210/B310): approx. 65–70 hp (48–52 kW)
- A12A versions: approx. 60–65 hp (45–48 kW)
Torque output measures: Approx. 69–74 lb-ft (94–100 Nm) at 3600 rpm. The
firing order is 1-3-4-2. Idle speed is generally 650–800 rpm depending
on carburetion and emissions controls.
The A12 uses a rigid cast-iron cylinder block designed for long service
life. Cylinder walls are thick and can handle multiple overbores during
rebuilds. The block casting changed slightly over time to accommodate
different engine mount positions, accessory locations, and emissions
provisions.
The crankshaft is a forged-steel, fully counterweighted design supported
by five main bearings. The five-bearing layout offers smooth operation
and excellent durability at sustained high rpm. Main and rod bearings
are generously sized, contributing to engine longevity.
Connecting rods are forged steel with reliable metallurgy suitable for
high-mileage work. Pistons are aluminum alloy with three-ring packs: two
compression rings and one oil-control ring. Piston design varies
slightly among versions, but all use full-floating wrist pins.
The cylinder head is cast aluminum with wedge-type combustion chambers
optimized for stable flame propagation. The A12 is an overhead-valve
(OHV) pushrod engine. The camshaft is located in the block and driven by
a steel timing gear set. Gear-driven camshafts eliminate timing-chain
stretch and offer extremely long service life.
Valves are actuated by:
- Camshaft lobes
- Solid lifters
- Pushrods
- Rocker arms
Valve sizes vary slightly:
- Intake valves: approx. 34–35 mm (1.34–1.38 in)
- Exhaust valves: approx. 30–31 mm (1.18–1.22 in)
Valve lash must be adjusted periodically.
Cold clearances:
- Intake: 0.35 mm (0.014 in)
- Exhaust: 0.35–0.40 mm (0.014–0.016 in)
The A12 uses a carbureted fuel system. Most versions use a single
downdraft Hitachi carburetor, though some regional models have Nikki or
Aisan units. Twin-carburetor setups were used on motorsport and
performance variants.
Fuel-system characteristics:
- Mechanical fuel pump mounted on block
- Paper-element inline fuel filter
- Float-bowl with needle valve
- Main jet, idle jet, power valve circuits
- Manual or automatic choke depending on year
Fuel delivery pressure is low, typically around 2.5–4.0 psi.
The A12 uses a full-pressure lubrication system with a gear-type oil
pump.
Oil is routed to:
- Crankshaft main bearings
- Connecting rod bearings
- Camshaft bearings
- Rocker arms via oil galleries
- Valve lifters and pushrods
Oil capacity: 3.0–3.2 liters (3.2–3.4 US qt) including filter
Recommended viscosity: SAE 10W-30, 10W-40, or 20W-50 depending on
climate
Oil pressure:
- 3000 rpm: 350–450 kPa (50–65 psi)
- Idle: >70 kPa (>10 psi)
Cooling is provided by a belt-driven centrifugal water pump. Coolant
flows through the block, head, radiator, and heater core.
Thermostat characteristics:
- Begins opening at approx. 82°C (180°F)
- Fully open near 95°C (203°F)
Cooling system capacity:
- Approx. 5.5–6.0 liters (5.8–6.3 US qt)
The system includes:
- Crossflow radiator
- Mechanical cooling fan (some with clutch)
- Thermoswitch for electric fan in later models
| Intake and Exhaust Systems |
Induction varies by carburetor version but
generally uses:
- Dry-paper air filter
- Steel or plastic air cleaner housing
- Cast-aluminum intake manifold
The exhaust system uses a cast-iron manifold with a two-into-one outlet.
Motorsport versions use tubular headers for improved flow.
| Ignition and Electrical System |
Ignition is controlled by a distributor mounted on the block.
Depending on model year:
- Early versions use breaker points
- Later versions use electronic ignition modules
Distributor features:
- Mechanical centrifugal advance
- Vacuum advance diaphragm
Spark plugs: NGK B6ES or equivalent
Gap: approx. 0.8 mm (0.031 in)
Ignition is set between 8° and 12° BTDC at idle with proper advance from
mechanical and vacuum sources.
Alternator output ranges between 35 and 50 amps depending on year.
Depending on production year, the engine
may include:
- PCV system
- EGR valve (emissions markets)
- Anti-dieseling solenoid
- Charcoal canister (EVAP)
- Thermal vacuum switches
- Length: 540–560 mm (21.3–22.0 in)
- Width: 520–540 mm (20.5–21.3 in)
- Height: 600–650 mm (23.6–25.6 in)
Dry weight: 90–105 kg (198–231 lb) depending on accessories
Recommended service intervals:
- Oil and filter: every 5000–8000 km (3000–5000 mi)
- Air filter: every 20,000 km (12,000 mi)
- Fuel filter: every 20,000–30,000 km
- Spark plugs: every 10,000–15,000 km
- Valve lash adjustment: every 20,000 km
- Coolant: every 40,000 km or 2 years
- Compression (healthy engine): 150–170 psi (1034–1172 kPa), variation
<10%
- Cylinder head bolts: 100 Nm (74 lb-ft)
- Main bearing caps: 65–75 Nm (48–55 lb-ft)
- Connecting rod bolts: 45–50 Nm (33–37 lb-ft)
- Flywheel bolts: 85–90 Nm (63–66 lb-ft)
- Crankshaft pulley bolt: 130 Nm (96 lb-ft)
- Intake manifold bolts: 22 Nm (16 lb-ft)
- Exhaust manifold nuts: 28 Nm (21 lb-ft)
- Spark plugs: 18 Nm (13 lb-ft)
- Oil drain plug: 34 Nm (25 lb-ft)
The Nissan A12 engine powered numerous
vehicles:
- 1970–1973 Datsun 1200 / Sunny B110
- 1974–1978 Datsun B210
- 1979–1982 Datsun/Nissan B310
- Nissan Sunny trucks / utility pickups
- Nissan Cherry (select trims)
- Nissan Vanette (light-duty)
- Various forklifts, industrial engines, and agricultural equipment
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| Outboard Engines Technical Specifications |
