A Engine Redesign

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For the 1974 season, the Nissan A-series engine was redesigned. The previous 1971-1973 A12 now was different from 1974-up. Changes were needed to fit more engine accessories like power steering and emission air pump. This required moving the distributor back. The engine mounting points were also moved.

Also see: A Series Engine Swaps

Accessory-Mount Changes

• Alternator moved from lower left side, to upper right side (where the distributor formerly was positioned)
• Distributor moved from below No. 1 spark plug, to below No. 3 spark plug. This requires a new block casting.
• Oil Pump drive shaft lengthened from 69mm to 70.5 mm, but Oil pump stays in same spot
• Fuel pump location moved forward, which necessitated:
  • Longer fuel pump rod (fuel pump thus being different)
  • Camshaft change to move position of fuel pump cam
  • oil dipstick moved lower down and forward (now adjacent to oil pump)
• Air conditioning compressor now can be fitted to lower left side
  • For 1975, an additional bolt boss was added

Engine Mount Changes

• Engine mounts moved back about 2"
  • Engine pan changed to mid-sump?
• Front rubber mount fitted with roll stopper, to prevent excessive engine roll
• Rear rubber mount (transmission mount) fitted with roll stopper, which helps prevent engine from moving forward in an accident

Miscellaneous Changes

• Baffle Plate re-designed (but in same location)
• Crankshaft flywheel-flange drilled for M10 x 1.25 Metric bolts (previous engines used English 3/8" x 24 UNF threads)
• auto flex plate bolt holes increased for 10mm to 10.5mm
• Oil lip seal added to exhaust valves (previously only fitted to intake valves)

Cylinder Head Changes

• Oil passage for rocker arm now drilled in the block, intead of in the head. This is important to note for interchange of A Type Cylinder Heads
• Special metal alloy for intake and exhaust valves
• Head Drilled and tapped for water temp switch on front left side (previously, only a boss was cast)
• Boss added between spark plugs No.1 and No. 2. This is for bolting the fuel line to the head, instead of to the Rocker Cover as previously done. Allows removing the rocker without moving the fuel line.
• Stronger head bolts