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[Datsun 1200 encyclopedia]

A-series Engine Swaps

(Redirected from A-Series Engine Swaps)

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Categories: Engine Modifications | Engine Swaps

The A14 and A15 engines are "tall deck" engines, and are 3/4 inch higher than A12s. However, they fit in the 1200 with only minor changes. This also applies to the 1974 A13 engine. The A14 and A15 are by far the most popular swapping candidates since the bigger displacement of the A14 and A15 means both more power (peak HP) and more low-speed power (torque) than the A12, A13 or A12A. Remember: "There is no replacement for displacement" (aka "theres no substitute for cubic inches").

Contents

Swap Factors

These factors are different when swapping:

  • 1967-1973 motor mounts vs 1974-up mounts
  • increased deck height raises exhaust pipe
  • 3-bolt vs 2-bolt exhaust flange
  • A14 & A15 call for stronger transmission
  • Call for stronger differential than 1967-1974 H145 type


776.jpg A14T Engine

4779.jpg A15 Engine deck

4780.jpg A15 Engine (left side)

Like all 1974-up engines. the A14/A15 have the motor mount bosses in a different place compared to the 1971-1973 A12 engines. So the engine mounts are a bit different. This photos illustrates the difference:
1779.jpg
Stock left-side mount in Datsun 1200, but Newer A12 engine. A better way is to move the brackets on the engine, to get the engine lower. You could also 1) use the 1974-up 1200 crossmember or 2) modify the crossmember.

Transmission

If upgrading a 1970-1972 Datsun 1200 to an A14 or A15, use the stronger 4-speed that comes with the A14 or A15. It is a bolt-in replacement.

If your 1200 has the 56A 4-speed (from 1973 up) it is strong enough for an A15. Look on the right side of the gearbox for the letter 56A and you are golden.

Differential

The stock H145 from a Datsun 1200 coupe/sedan/wagon is not rated for the torque of an A14 or A15. It can handle the horsepower, but not the torque.

While some club members have had their H145 last behind an A14, more have had it break. It is the ring & pinion gears (CWP) that break, not the axles.

You can either:

  • Fit an H150 diff center into your 1200 housing. H150 came with 1975-1978 B210 and 1979-1982 B310

or

Engine Mounts

The easiest thing to do is use a matching set:

Or the complete set of early items if swapping an early engine into a later 1200. For more details and comparison photos, see Engine Mounts.

20925.jpg

20924.jpg

Early vs Late Engine crossmembers
8487.jpg

RH engine mount brackets (old) 55mm bolt center (new) 50 mm bolt center
Lower bolt is 5mm higher on new engine, so mounts actually bolt at the same level.
23553.jpg

Perhaps a 3mm difference. Then add thickness of your adapter plate.
23552.jpg


Late Engine onto Early Crossmember

When fitting a 1974-or-newer engine into an orginal Datsun 1200, and using the original crossmber, modifications to the engine mount brackets are needed.

There is no need modify the crossmember, although that can be done. It is easy to modify the brackets.

25421.jpg Engine Mounts dimensions

Left Side Mount Location

Left Side (manifold side) of A-series engine

  • Engine mount bolt bosses were moved back 35mm (1-3/8") on the late blocks
  • 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


Engine mount boss is 35mm farther back on newer blocks
19202.jpg
5mm higher from bottom of block


Remove this Late LH bracket:
2564.jpg

And obtain another RH bracket, and then fit it to the LH side. Old A12 brackets won't fit, but new A12/A14/A15 brackets will:
20923.jpg

The mounts are also 35mm (1-3/8") further back. So drill two holes in a flat plate and mount it like this:
1779.jpg

If the engine is centered and the plate holes drilled correctly, it will fit straight as above.

If the engine is not centered, the plate can be skewed:
th_Photo-0283-1.jpg

There are three different RH mounts, some allow the engine to sit higher or lower than the others. If the mount is now up too high, slot the bolt holes for the engine bracket, and slide the mount up on the block the thickness of the plate, then tighten. This will lower the engine a bit.

Three different RH mounts. Which is best for a swap?
20945.jpg

154 mm: Early block front face to center of mount
23475.jpg

189 mm: Revised block front face to center of mount
23474.jpg

Alternatively, you can put the mount on the last accessory bosses (as in the photo of the Yellow A14 block), which is 26mm (1") farther forward. To do this, you will need to redrill the lower hole on the engine mount bracket, 8mm over. And you will still need to slot the mounts and use a flat plate. Nothing gained, but it takes a little more work this way.

Right Side Mount

Right side (spark-plug/oil pump/starter side) engine mount bracket is practically the same Late vs Early.

2563.jpg

Two types of right-side brackets:
20923.jpg

The only thing you might need to do is Measure engine installed angle and if you need to lower it a little bit, slot the bracket bolt holes (where it bolts to the engine) slow you can mount it slightly higher.

Custom Brackets

For the cleanest look, you may cut and re-weld the brackets so they fit just so. You can fabricate the LH and RH brackets to have the 35cm offset and be a bit lower.

Discussions and Details

The simplest way to fit the motor mounts is a flat plate:

Photo-0283-1.jpg

However, this might makes the engine sit about 5/16" too high. You could slot the bolt holes in the engine bracket so it will slide slightly to level the engine. Or if you use the correct new bracket it will be very close as-is. Only about 4mm higher.

Early Engine onto Late Crossmember

You can either fit an early crossember to the newer 1200, OR just use the newer mounts with simple metal plates on each side.

Crossmember Swap

Swap the crossmeber? Swapping crossmembers is fairly easy. There are two bolts on each side, plus the LCA bushing mount. But you don't have to swap crossmembers -- it's just one way of doing it. Perhaps the most elegant way. See Changing Crossmembers.

23609.jpg

Use Newer Mounts

Or use newer engine mounts? You can modify the engine mount brackets to fit an early A12 engine (GX, anyone?) into your later 1200.

The only trick is to drill a flat plate to bridge the 35mm difference in back-to-front location.

  1. Use Datsun 1200 RH mount
  2. Use 120Y A12 or B210 A14, or any B310 LH mount with a longer bolt
  3. Drill two holes in 4mm flat plates

4mm thick plates. The mount bracket overlaps the insulator so it is partially supported by it.
23572.jpg 23573.jpg

Use the 1200 lower radiator hose to clear the alternator.

Right Mount Bracket

The original A12 RH bracket is very similar to the newer bracket (but the newer RH bracket doesn't fit the old engine).

Left Mount Bracket

On the LH side, use a LH engine bracket from a late engine. The newer LH bracket will match the newer or older LH crossmember horn. The height is perfect and no adjustment is needed.

Old A12 uses stepped bracket (upper boss is set back). To fit New A12 bracket, remove the stud and use a longer stud, or a bolt.
23554.jpg

To fit the new A12 bracket, use 19mm worth of washers and a longer bolt or stud. Bolt centers are the same for the original A12 stepped bracket and the revised A12 flat bracket.
23555.jpg

Swap Notes

  • 1200 wiring will reach either Distributor (under #1 or under #3)
  • Alternator fits on opposites sides
    • Can refit alternator to other side, but not necessary
    • use extension wires to reach across (Ground, Battery, and FN/LS wires). Be sure to use the same thickness (gauge) as original.
    • If you newer 1200 does not have a voltage regulator, fit an Internally Regulated alternator. Later Datsun 620/720 is a direct bolt on. See Hitachi LR Alternator
  • Radiator hoses are different for the original 1200 low-mount alternator.

HB210

North American B210 with A14 engine pan changed to mid-sump. So if swapping this engine in, swap the pan and pickup tube with the newer B310 A14/A12A unit.

B310

B310 fits all A-series from 1974

th_B310-crossmember-3.jpg th_B310-crossmember-1.jpg th_B310-crossmember-2.jpg

Questions

  • What's Better? A14 or A15?
  • But isn't the A15 stroke to long to rev high?
  • Isn't the rods too short in the A14?

For answers, see: Engine Swaps, section "A-series Nissan Engines"

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This page has been accessed 17,864 times. This page was last modified 03:40, 2 April 2014. Content is available under Datsun 1200 Club.