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[Datsun 1200 encyclopedia]

A-series Engine Changes

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Category: Engine Mechanical

North American A-series engine Changes



For 1970 calendar year and 1971 Model year.

The A12 was introduced in 1970. It improved upon the A10 with these major features:

  • Longer stroke for increase displacement
  • 5-bearing crank compared to 3-bearing for the A10
  • closed crankcase emission with PCV valve (CRANK emission control)

A12 Details, improvements upon A10

  • Crank stroke is 11mm longer, now 70 mm, up from 59mm
  • Block height 10mm higher
    • Connecting rods are 4 mm longer
    • push rods are 10.5 mm longer, now 152 mm, up from 141.5 mm
  • Oil slinger at rear
  • closed blow-by tube for PCV system
  • T-shaped crankshaft oiling
  • connecting rod cap lightened yet strengthened with 1mm longer bolt boss
    • Same improvement added starting with A10-728641
    • Oil pump driveshaft decreased 1.5 mm to clear the new cap design
  • F770 (copper-lead) main and rod bearings
  • Improved piston shape with larger relief cut in the skirt
  • combined oil ring
  • New dual-pitch valve springs
  • Flywheel is 9kg, up from 8kg for the A10. Disc face is moved 3mm backward
    • "flywheel contacting face of the gear case has been ground 0.1772 in (4.5 mm)". A12 starter will work on A10, but not vice-versa. A12 uses Hitach S114-87L starter
  • Oil pan shape differs
    • Oil pickup differs
  • Engine Fan increased 20 mm to 300mm for 20% more efficiency, and material changed from press steel to polypropylene for quieter operation
  • Radiator tank sized decrease, core size retained, efficiency increased
  • larger carburetor (DCG-306) fitted, replacing DCG-286
    • Stud mounted air cleaner instead of band-secured type
  • Fuel pump now 2.6 psi, up from 2.3 psi (via stronger spring)
  • Intake manifold carb flange now at 5 degrees, up from 3 degrees due to engine mounting angle change.
    • Plenum changed to dual primary/secondary passages
  • Exhaust manifold inside diameter increased to 34mm up from 30 mm
    • Straighter bends
  • Alternator changed to 2-conductor T-shape connector, instead of previous 4-conduction connector


  • All A12s feature CRANK emission control (PCV system)
  • USA models feature EXHAUST emission control (carb & spark timing changes)
  • USA models feature EVAPO emission control (closed fuel tank/carb system)


  • does not implement EXHAUST or EVAPO
  • uses non-EXHAUST distributor advance curves

Cast iron crankshaft, 5 bearing (as opposed to 3-bearing crank for A10 engine).


  • Cam specs: 62-62 degrees, lift in: 5.33 mm ex:5.33 mm, intake opens 14 BTDC closes ABDC 54, exhaust opens BBDC 56 closes ABDC 12


    Why the A13? To bring performance back after the Sunny becomes heavier and (in North America) 2nd-gen emisssions controls reduce engine output. This is the start of the A Engine Redesign.
      • To make room for more engine accessories, engine mount points moved back, and distributor moved back from under #1 spark plug to between #2 and #3 plug, fuel pump moved. In turn this means the camshaft is changed to drive the new fuel and distributor locations
      • EGR introduced. Both intake and exhaust have fittings for EGR
      • A13 tall-deck engine introduced. This is the only engine available for North America. It is a stroked A12, but with a new block that is 15mm (0.59 inch) higher than other A-type engines.
      • New oval intake ports, (midsize oval) of 28 mm x 30 mm
      • Oil pan is now a mid-sump design (1200s used a front sump). Oil capacity increased to 3.5 liter. Oil gasket shape changes
      • rocker oil passage around head bolt enlarged. No longer requires a special head bolt
      • Carb: EGR port added. Venturis up from 20/26 to 22/27
      • Radiator, same as Datsun 1200 except more fins, so efficiency is up 13%. Fan is now 330mm up from 310mm.
      • new fuel pump with longer lever (not compatible with A12)
      • Water temp switch moved from right side of head to left side. This means the head gasket is different
      • valve seat alloy changed <li>head bolts are strengthened, and have a higher torque setting
      • head has new boss to clamp fuel line between #1 and # 2 cylinders on spark plug side
      • piston heads have a 1cc larger dish
      • valve sizes increased, in: up 2mm to 37, ex: up 1mm to 30
      • intead of umbrella-type valve seals, now using lip-type
      • because the stroke and deck height changed, rods are now 11.5 mm longer
      • crank now uses Metric M10 1.25 bolts to attach flywheel instead of english-system 3/8" x 24 UNF bolts
      • cam profile changed to 62-64 degree (up from 62-62 for '73 A12). Exhaust lift increased 0.27 mm to 5.6 mm. Exhaust valve closes 8 degrees additional ABDC
      • auto trans driveplate bolt holes are 0.5 mm larger
      • engine mount spring constant lowered for decreased noise at medium and high speeds. Also a roll stopper is added.
      • exhaust and intake manifolds have larger cross-section, but intake has partially-siamesed ports. New heat riser design for faster warmup.


      The A14 engine debuts in North America B210 models.

      Why the A14? To bring performance back after the Sunny becomes heavier yet. This increased torque also calls for stronger H150 diff and stronger 60-series 4-speed, and stronger clutch cover (up from 694 to 794 kg), as well as stronger front springs

        • cold air intake added to air cleaner
        • 1974 A13 design is now bored out to 76mm to give 1397 cc. This uses a new block with a boss for the air pump
        • Head center exhaust ports are no longer siamesed
        • Larger intake oval ports, up from 28x30 to 28x34 mm, though still smaller than the ports on the A12GX engine. Intake manifold ports are larger to match (and no longer semi-siamesed)
        • Exhaust outlet changed from 2-bolt to 3-bolt design
        • heat riser improved with waved stove plate. New heat shield added
        • Rod small-end bore increased 1.6 mm for strength
        • Carb: Auto choke now uses PTC heater for more consisten t operation
        • Heat shielding introduced: under carb, between throttle plate and carb body, between intake & exhaust manifolds, and stainless bolts for carb, intake & exhaust (stainless transmits less heat)
        • New larger diameter distributor. Both points and electric units use same. California gets electronic ignition.
        • Flywheel weight increased 1kg over the A13. It's also 3mm thicker
        • Carb: primary venturi upped to 23mm from 22 previously
        • Radiator: 474 x 330 x 32, up from 334 x 330 x 32. Auto models have a smaller fin pitch, and new cooler lines (previously the auto trans used a separate air cooled radiator)
        • engine mount spring constant increased (because of the extra torque of the engine) after being decreased for 1974. A heat shield is added to the left mount to deflect exhaust heat
        • Air injection introduced. Air passage added to cylinder head
        • Factory air-conditioning (A/C) introduced for first time in Sunny line. Previously only dealer-installed or aftermarket A/C was available. AC models use a larger 350 mm fan with a hydraulic coupling. Fan spacer for non-A/C models increased to 28.5 mm to match (up from 18.5 mm).
        • charcoal canister added, so the Flow-control valve is no longer needed. Now rocker cover can vent to outside of air cleaner element, thus preventing eventual sludging of carburetor jets.


        The usual year-by-year changes to emissions controls for North America:

        • California models get catalytic converter
        • exhaust manifold outlet angled 37 degrees back (instead of 25)
        • Radiator: M/T cars get smaller radiator (404 x 330 x 32)
        • oil pan baffle plate added, with plug on bottom. Oil level lowered, dipstick L-H now 1 liter (from 1.3 liter previously)
        • 1976-1/2: GFU models debut (F = 5-speed, U = USA), The A14 FU engine gets round-ports to increase swirl. Intake manifold is modified to match. [comment: Now it becomes obvious the 63a 5-speed was added for fuel economy, not for performance]. Other models continue with open chamber oval-port heads.
        • FED models drop pre-muffler at half of the year


        • Head: US models get threaded hole at left rear for TCS valve. Canada remains unchanged.
        • Intake manifold: PCV hole raised, so new PNs for all intakes
        • USA Exhaust manifold: EGR port size increased from M16 to M22
        • New improved A/C, now integrated into heater system
        • CAL engines get altitude-compensating carburetor
        • USA engines get variable choke-break
        • Larger catalyst, floor modified (CAL)


        • Canada heads change to quench wedge chamber as on 1977 GFU heads.
        • USA 5-speed cars get 9.0 compression (4.08 mm piston dish), other engines stay at 8.5 (5.37 mm piston dish).
        • Introduction of optional reduction gear starter (standard in Canada). All engines have mount brackets modified to accomomdate this. The mounts are pushed outside 31.4 mm, and lowered 15.9 mm.
        • Canada exhaust manifold now same as 1977 USA models
          • 32mm EGR boss now 32mm M22 thread (up from 25mm M16 thread)
        • Alternator with integral IC regulator introduced
        • Longer oil filter employeed to eliminate 1,000 mile service interval
        • Slightly smaller converter adopted (only CAL and FU have converter)
        • Transistor ignition used by 1977 FU model now used for all USA
          • Canada still uses points
        1977 GFU: 8.5:1 with 5.37 mm dish
        1978 CAN: 8.5:1 with 5.37 mm dish
        1978 GFU: 9.0:1 with 4.08 mm dish


        4th Generation Sunny (B310) model marketed in North America as "Datsun 210"

        • A15 engine introduced in Wagon with Automatic transmission
        • New D4K distributor with "black box" electronic ignition debuts
        • For 5-speed models, main and rod bearings get low-friction metal blend
        • No A12A engine offered
        • Auto: 3.889, MT: 3.700 H150 differentials
        • FS5W60L 5-speed dogleg one-year only
        • FU=KFU FED only (A14) MPG motor. Other FUs this year are traditional
          • 4-angle valve seat (same as CAL/CAN)
          • 8.9 (same as CAL) instead of 8.5 compression ratio
          • Fuel Shut-Off System (instead of Throttle Opener)
            • Hitach DCH306-67
            • Dual-mode spark Vacuum Advance (intake vacuum works at idle, improving fuel economy)
            • Double-lead anti-diesel valve
            • 16767-H7280 UNIT-ENGINE REVOLUTION A14 FED(KFU) B310 [Engine Rev Switch, 1000-1150 RPM)
            • 16024-H7281 THROTTLE SWITCH ASSY A14 FED(KFU) B310 [Throttle Valve Switch]
            • 32130-H9011/32130-H9010 EXTENSION ASSY-REAR [unique, but others may work]
            • 32006-K2401 SWITCH COMP-NEUTRAL COUPE 5-SPEED(CAL),FED KFU Neutral Detecting Switch replaced 32130-H9705 32006-K2400
            • 10mph switch in speedometer
          • Catalyst w/o air pump (has AIS)
          • BP5EQ-13/L46PM-13 [large gap]
        • Fan: Torque Coupling with CAL A/C, limits fan speed to 2900 RPM
        • Fan: TEM Coupling with FED A/C, 2900 RPM except when ambient cool, 2050 RPM
        • Accelerator Pump stroke limiter
        • Altitude Compensator eliminated from CAL models


        • Carb: A12A primary venturi is 20 mm (same as '73 A12)
        • Carb: A14 & A15 primary venturi lowered to 22 mm (down from 23)
        • A15 engines get moly-coated piston skirts for lowered friction


        • All USA engines get medium-oval port heads with a shrouded swirl ports. A12A, A14 and A15 all use the same head.
        • ... to be continued


        No changes from 1981

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