Engine block

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The A12 engine of the Datsun 1200 features a modern lightweight cast-iron cylinder block. For an overview of all A-series engines see Block Comparison.

Identification

A12 can be positively identified by looking for the engine Stamped ID - see main article: Engine ID Mark

Ventilation

Under the block breather pipe, this steel mesh separates out the oil vapor from crankcase ventilation air.

Dimensions

A12 Deck Height is 189.1 mm. A10 engines are 10 mm shorter, and A14 is 15 mm taller. For more details see Block Comparison#Dimensions.

Length is the same for a A-series engine blocks.

Head Locating Dowels

Starting with A12 engine for B210 and including later 1200, dowels were used to locate the Cylinder Head.

full

11053-73400 DOWEL-BLOCK TO HEAD 14 diameter 2

Cylinder Blocks

Also see: Block Comparison

The block has ~2.5 liter coolant capacity.

Original Block

11010-H2300 A12 BARE BLOCK 73mm/2.87" bore size 
* running change replaced 11010-H1000

H10 block castings

Redesigned Block

* 11010-H5000 A12 B120 From July 1973 (?)
* 11010-G1600 A12 B120 From June 1975 (?) 
* 11010-G1618 A12 B120 7908-8503
* 11010-G1619 A12 B120 8504- (M79 casting)

H50 casting, from 1974-1985(?) Datsun 1200

M79 casting, from 1985-1994 Datsun 1200

Overbore

The 1971-1973 A12, the one with the front distributor, can usually be bored to 76mm. This is the same as a stock A14 and will increase HP much more than going to high compression.

See main article: Bored And Stroked

Crankshafts

A12 uses a forged crankshaft, so it is plenty strong -- even for 8500 RPM use.

Stroke: 70mm (2.76 in.)

For more details and part numbers, see Crankshaft

Connecting Rods

Stock A-series rods are forged, and will last a lifetime in a stock or moderately upgraded performance engine. There is no need to use a heavier duty rod unless you are using a high boost turbo or supercharger, or revving higher than 8500 RPM.

See main article: Connecting Rods

Pistons

A12 engine came with dished pistons for approximately 9.0:1 compression ration. Standard bore size for the A12 or A13 block is 73mm/2.874". Pistons are cast. Nissan Competition does not recommend forged pistons for street use.

See main article: Piston

Main Bearing Caps

Also see: ARP

12293-18001 BOLT-MAIN BEARING CAP (10) L=72.5 <> 12293-01M00
* A12/A14/A15 engine (quantity 10)
* L16, L18 and L20B engine (10)
* 720,D21,S110 with Z20/Z22/Z24E/Z24I (10)
* 910,S130 with L24/L28E (14)
* B11, N10/N12 with E15/E16 (10)
* D21 PICKUP with KA24E engine (10)