The A12 engine uses a lightweight cast iron block and aluminum cylinder head, with overhead valves and a camshaft. The engine was equipped with a Hitachi two-cylinder carburetor (double choke). The bore and stroke were 73.0 mm (2.87 inches) and 70.0 mm (2.76 inches), respectively. The compression ratio is 9.0: 1. The A12 produced 71 PS (52.0 kW; 70.0 HP) of horsepower and 95 Nm (9.69 kg · m; 70.11 ft · lb ) of torsion.
For the 1974 model year, the A12 engine was modified, the new block style was used. The distributor was moved from the front of the engine to the middle of the engine block to make room for an air conditioning system and anti-pollution air pump. The redesigned Nissan A12 engine used new emission control technology, called NAPS (Nissan Anti-Pollution System).
- the A12GX It was equipped with twin Hitachi side-firing carburetors and longer-lasting camshafts. The compression ratio was 10: 1 and the maximum power was 84 PS (62 KW; 83 HP) at 6,400 rpm. The A12GX was used in the Sunny 1200 GX (Sedans and Coupes) for the JDM market.
- the A12T It had an identical specification to the A12GX and was used in the Nissan Cherry X-1.
- the AY12 It was the racing version of the A12 engine with 1,300 cc (79 cubic inches) of displacement, a cross-flow cylinder head, a special piston design, and a valve rocker system.
The engine code breakdown is as follows:
- TO – Engine family
- 12 – 1.2 liter displacement
- S – Carburettor type
|Design||Four stroke, Inline-4 (Straight-4)|
|Fuel type||Gasoline (gasoline)|
|Displacement||1.2 L, 1,171 cc (71.45 cu in)|
|Fuel system||Carburettor type|
|Power output||71 hp (52.0 KW; 70.0 hp)|
|Torque output||95 Nm (9.69 kgm; 70.11 ftlb)|
|Order to open fire||1-3-4-2|
|Dimensions (L x W x H):||–|
The A12 has a cast iron cylinder block that uses a five bearing support system. The cylinder bore is 73.0 mm (2.87 in) and the stroke is 70.0 mm (2.76 in). The A12 engine has two compression and oil control rings.
|Cylinder Block Alloy||Molten iron|
|Compression ratio:||9.0: 1|
|Cylinder bore:||73.0 mm (2.87 inches))|
|Piston stroke:||70.0 mm (2.76 inches)|
|Number of piston rings (compression / oil):||2/1|
|Number of main bearings:||5|
|Cylinder bore (standard):||73.000-73.050 mm (2.8740-2.8760 inches)|
|Piston Skirt Diameter (Standard):||72.967-72.017 mm (2.8727-2.8747 inches)|
|Piston Pin Outside Diameter:||17.447-17.452 mm (0.6869-0.6871 inches)|
|Piston ring side clearance:||Top||0.040-0.070 mm (0.0016-0.0028 inch)|
|Second||0.040-0.070 mm (0.0016-0.0028 inch)|
|Petroleum||0.10 mm (0.0039 inch)|
|Piston Ring End Gap:||Top||0.20-0.35 mm (0.0079-0.0138 inch)|
|Second||0.20-0.35 mm (0.0079-0.0138 inch)|
|Petroleum||0.30-0.90 mm (0.0118-0.0354 inch)|
|Crankshaft journal diameter:||49.943-49.964 mm (1.9663-1.9671 inches)|
|Crankpin diameter:||44.954-44.974 mm (1.7698-1.7706 inches)|
|Connecting rod center distance:||121.5 mm (4.78 inches)|
The valve system has a pushrod-type rocker arm that uses valve springs of only one type. The camshaft is driven by a double row roller chain from the crankshaft. Chain tension is controlled by the chain tensioner which is operated by spring and oil pressure. The rubber shoe type tensioner isolates chain vibration and controls chain tension.
The intake valves are 35.0 mm (1.378 in) diameter and the exhaust valves are 29.0 mm (1.142 in).
|Valve layout:||OHV, chain drive|
|Valves:||8 (2 valves per cylinder)|
|Valve timing:||CONSUMPTION||248 °|
|Valve head diameter:||CONSUMPTION||35.0 mm (1.378 inches)|
|Tired||29.0 mm (1.142 inches)|
|Valve length:||CONSUMPTION||102.35-102.65 mm (4.030-4.031 inches)|
|Tired||102.35-102.65 mm (4.030-4.031 inches)|
|Valve stem diameter:||CONSUMPTION||7.960-7.975 mm (0.3134-0.3140 inches)|
|Tired||7.945-7.960 mm …|