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North American A-series engine Changes
Contents |
1973
- 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
1974
Why the A13? To bring performance back after the Sunny becomes heavier and (in North America)2nd-gen emisssions controls reduce engine output-
<li>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
<li>EGR introduced. Both intake and exhaust have fittings for EGR
<li>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.
<li>New oval intake ports, (midsize oval) of 28 mm x 30 mm
<li>Oil pan is now a mid-sump design (1200s used a front sump). Oil capacity increased to 3.5 liter. Oil gasket shape changes
<li>rocker oil passage around head bolt enlarged. No longer requires a special head bolt
<li>Carb: EGR port added. Venturis up from 20/26 to 22/27
<li>Radiator, same as Datsun 1200 except more fins, so efficiency is up 13%. Fan is now 330mm up from 310mm.
<li>new fuel pump with longer lever (not compatible with A12)
<li>Water temp switch moved from right side of head to left side. This means the head gasket is different
<li>valve seat alloy changed <li>head bolts are strengthened, and have a higher torque setting
<li>head has new boss to clamp fuel line between #1 and # 2 cylinders on spark plug side
<li>piston heads have a 1cc larger dish
<li>valve sizes increased, in: up 2mm to 37, ex: up 1mm to 30
<li>intead of umbrella-type valve seals, now using lip-type
<li>because the stroke and deck height changed, rods are now 11.5 mm longer
<li>crank now uses Metric M10 1.25 bolts to attach flywheel instead of english-system 3/8" x 24 UNF bolts
<li>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
<li>flywheel weight increased for smoother running
<li>auto trans driveplate bolt holes are 0.5 mm larger
<li>engine mount spring constant lowered for decreased noise at medium and high speeds. Also a roll stopper is added.
<li>exhaust and intake manifolds have larger cross-section, but intake has partially-siamesed ports. New heat riser design for faster warmup.
- 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. Now they are similar to 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 cannister 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.
1975
A14 North America 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
1976
<li>The usual year-by-year changes to emissions controls <li>California models get catalytic converter <li>exhaust manifold outlet angled 37 degrees back (instead of 25) <li>Radiator: M/T cars get smaller radiator (404 x 330 x 32) <li>oil pan baffle plate added, with plug on bottom. Oil level lowered, dipstick L-H now 1 liter (from 1.3 liter previously) <li>
1977
<li>Head: US models get threaded hole at left rear for TCS valve. Canada remains unchanged. <li>Intake manifold: PCV hole raised, so new PNs for all intakes <li>USA Exhaust manifold: EGR hold increased from M16 to M22 <li>New improved A/C, now integrated into heater system <li>On GFU models (F = 5-speed, U = USA), The A14 engine gets round ports, lowered and have quench wedge chambers to increase swirl. These are round-port heads. 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.
1978
<li>canada heads change to quench wedge chamber as on 1977 GFU heads. <li>USA 5-speed cars get 9.0 compression (4.08 mm piston dish), other engines stay at 8.5 (5.37 mm piston dish). <li> Introduction of optional reduction gear starter (standard in Canada). All engines have mount brackets modified to accomomdate this. The mounts are push outside 31.4 mm, and lowered 5.9 mm. <li> Canada exhaust manifold now same as 1977 USA models <li>Alternator with integral IC regulator introduced
1979
<li> New distributor with "black box" electronic ignition debuts <li>For 5-speed models, main and rod bearings get low-fricion metal blend <li> ... to be continued
1980
<li>Carb: A12A primary venturi is 20 mm (same as '73 A12) <li>Carb: A14 & A15 primary venturi lowered to 22 mm (down from 23) <li>A15 engines get moly-coated piston skirts for lowered friction