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[Datsun 1200 encyclopedia]

Engine block

Revision as of 16:08, 20 July 2007; view current revision
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Category: Engine Mechanical

770.jpg A12 Engine ID Mark

Contents

Cylinder Blocks

  • 11010-H2300 A12 BARE BLOCK 73mm/2.87" bore size
  • 11010-H9960 A12A BARE BLOCK 75mm/2.95" bore size
  • 11010-H6200 [1974] A13 BARE BLOCK 73mm/2.87" bore size
  • 11010-H9700 A14/A15 BARE BLOCK 76mm/2.99" bore size


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. There are probably some dud blocks around, but generally 76mm is fine. Pistons of 76.5 mm size and larger were offered through the Datsun competition department and others back in the 70's, so it's a factory approved bore size.

A14 pistons use a 19mm wrist pin while the A12 rods have a 17.5mm hole, so you have choices:

  • Bore the original rod to 19mm. This is most commonly done
  • Find a set of late A12 rods. There seems to have been a change in the later rods and these forgings look like they are the ones that were used for the A12A & A13 engines. [more on this later]. These rods have more 'meat' around the pin hole & would be stronger than a 1200 rod after the pin hole was bored to 19mm.
  • Find a set of A12A or 1980's A13 rods as these have the right length and the correct wrist pin hole for the A14 pins


73mm bore piston used the 17.5mm piston pin diameter:

  • A10
  • 1971-1973 A12 (1200)
  • 1974-up A12
  • 1974 A13 (tall block engine)

A series pistons for engines with 75mm bore used a 19mm pin:

  • A12A - USA & Japan only

76mm bore size also used the 19mm pin:

  • A14
  • A15
  • 1979-'81 (Asia only)

A12A and late A13s were just bored out A12s, so they had the shorter A12 length rods, but with the bigger pin size. The crankshaft is interchangeable between early A12, late A12, late A13 and A12A.

Crankshafts

  • 12200-H8515 A12/A12A CRANKSHAFT 70mm/2.76" stroke
  • 12200-H5720 A12 COMPETITION CRANKSHAFT 70mm/2.76" stroke
  • 12200-H8915 A13/A14 CRANKSHAFT 77mm/3.03" stroke
  • 12200-G3400 A15 CRANKSHAFT 82mm/3.23" stroke


MAIN BEARING (#1/#5, SHELL THICKNESS)
4 each required

  • 12215-H2310 .0720"
  • 12215-H2311 .0718"
  • 12215-H2312 .0715"


MAIN BEARING (#2/#4, SHELL THICKNESS)
4 each required

  • 12231-H2310 .0720"
  • 12231-H2311 .0718"
  • 12231-12312 .0715"


MAIN BEARING (CENTER, SHELL THICKNESS)
2 required

  • 12247-H2310 .0720"
  • 12247-H2311 .0718"
  • 12247-H2312 .0715"


Connecting Rods

4 of each required:

  • 12100-H1000 A12 CONNECTING ROD 121.5mm/4.78" center-to-center
  • 12100-18500 A12A CONNECTING ROD 121.5mm/4.78" center-to-center
  • 12100-16200 [1974] A13 CONNECTING ROD 133mm/5.24" center-to-center
  • 12100-17200 A14/A15 CONNECTING ROD 133mm/5.24" center-to-center


ROD BOLT The Datsun rod bolt is a true stretch bolt and should be torqued only once. New bolts should be installed at every disassembly. 8 each required:

  • 12109-H1001 CONNECTING ROD BOLT
  • 12112-H1000 CONNECTING ROD NUT


CONNECTING ROD BEARINGS The -25720/-H2310 bearing shell produces the most desirable bearing clearance for racing purposes when applied to a standard size crankshaft. The other shells exist in order to obtain proper clearance when compensating for the variations in the crankshaft or connecting rod journals.

8 each required:

  • 12111-25720 .0590"
  • 12111-25721 .0588"
  • 12111-25722 .0585"
  • 12111-25723 .0592"
  • 12111-25724 .0583"

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.


A12GX engine came with two kinds of pistons:

  • dished for low-gas (regular octane) engine
  • flat-top for high-gas (high octane) engine


Piston Comparisons/Potential Swaps

?


Nissan Competition Parts 

NOTE: 99996- part numbers are Nissan Competition

A12/A13 FACTORY CAST FLAT-TOP PISTONS Cylinder wall thickness should be checked by sonic testing when increasing initial bore size in excess of 1 mm/.03937". Standard bore size for the A12 or A13 block is 73mm/2.874".

  • 12010-H2361 73MM/2.874" PISTON


PISTON RING SET

  • 12033-H6200 RING SET FOR 12010-H2361
  • 12010-12364 73.5/2.894" PISTON
  • 12035-H6200 RING SET FOR 12010-H2364
  • 12010-H2366 74mm/2.913" PISTON
  • 12037-H6200 RING SET FOR 12010-H2366
  • 12010-H2310 73MM/2.874" PISTON Similar to 12010-12361 except for valve reliefs for increased piston-to-valve clearance
  • 12033-H6200 RING SET FOR 12010-H2310


ARIAS FORGED RACING PISTONS
All of the forged pistons are of the dome-top design. Modifications must be made to the spark plug side of the combustion chamber for proper clearance. The compression ratio will vary depending on the swept volume of the engine and amount of material removed from the cylinder head. Piston-to-wall clearance for forged pistons should be approximately.005" to .007". All forged pistons use a full-floating .750" pin retained by Teflon buttons. For this reason the A12 and A12A pistons require the use of the A12A connecting rod (12100-98500). Also, the A13 and A14 pistons require the use of the A14 connecting rod (12100-H7200). Because of the full-floating pin the small end of the rod should be sized with a clearance of .0006" to .0009". End gap for the top ring should be .012" to .015". The second ring should have an end gap of .010" to .013". Clearance on the oil scraper ring is not critical. Forged pistons are not recommended for street use. PART NO. DESCRIPTION QTY REQ.

  • 99996-H1017 73MM/2.874" A12/A13 PISTON 4
  • 99996-H1027 RING SET FOR 99996-H1017 1
  • 99996-H1022 REPLACEMENT PIN FOR 99996-H1017 4
  • 99996-H1123 REPLACEMENT BUTTON FOR 99996-H1017 8
  • 99996-H1011 74MM/2.913" A12/A13 PISTON 4
  • 99996-H1021 RING SET FOR 99996-H1011 1
  • 99996-H1022 REPLACEMENT PIN FOR 99996-H1011 4
  • 99996-H1127 REPLACEMENT BUTTON FOR 99996-H1011 8
  • 99996-H1060 76MM/2.992" A12A/A14 PISTON 4
  • 99996-H1065 RING SET FOR 99996-H1060 1
  • 99996-H1022 REPLACEMENT PIN FOR 99996-H1060 4
  • 99996-H1124 REPLACEMENT BUTTON FOR 99996-H1060 1
  • 99996-H1061 76.75MM/3.022" A14 PISTON 4
  • 99996-H1067 RING SET FOR 99996-H1061
    • This ring set is designed for 77mm/3.032" pistons, therefore, some sizing will be necessary to achieve the proper end gap. 1
  • 99996-H1022 REPLACEMENT PIN FOR 99996-H1061 4
  • 99996-H1023 REPLACEMENT BUTTON FOR 99996-H1061 8
  • 99996-H1062 77MM/3.032" A14 PISTON 4
  • 99996-H1067 RING SET FOR 99996-H1062 1
  • 99996-H1022 REPLACEMENT PIN FOR 99996-H1062 4
  • 99996-H1126 REPLACEMENT BUTTON FOR 99996-H1062 8


COSWORTH FORGED RACING PISTONS The only exception to the information provided in the above paragraph <for Arias pistons> is that the Cosworth piston still utilizes circlips to retain the full floating piston pin. PART NO. DESCRIPTION QTY REQ

  • 99996-H1170 76MM/2.992" A12A/A14 PISTON 4
  • 99996-H1175 RING SET FOR 99996-H1170 1

Interchange

Standard Size Piston Rings - Cast Iron Rings; Bore 75mm"; 8-2.0mm Comp and 4-4.0mm Oil Rings.

  • SEALED POWER #E-362X.STD, 9469X.
  • Hastings #2M-6813

Fits:

  • 1979-1982 Datsun/Nissan 210 4 cyl. 1.2L 1237cc A12A engine
  • 1971 & Up Mazda 4 cyl. 1.5L 1484cc UA engine
  • 1968-1969 Toyota Corolla 4 cyl. 1.1L 1077cc KC engine
  • 1969-1979 Toyota Corolla 4 cyl. 1.2L 1166cc 3KC engine
  • 1981-1982 Toyota Starlet 4 cyl. 1.3L 1290cc 4KC engine

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