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Revision as of 23:45, 3 August 2015

The A14 and A15 engines fit in the 1200 with only minor changes. 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 engine. Remember: "There is no replacement for displacement" (aka "theres no substitute for cubic inches").

Overview

The A14 and A15 engines are "tall deck" engines, and are 3/4 inch higher than A12. 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").

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
A15 calls for stronger transmission
A15 needs stronger differential than 1967-1974 H145 type

A14/A15 bolts directly into newer 1200 (1974 & newer utes).

Exhaust Pipe

A14/A15 use a 3-bolt exhaust flange. Datsun 1200 uses a 2-bolt exhaust pipe.

So get a short section of the exhaust pipe, and have it welded to your exhaust system.

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. Be sure to get the matching set: Flywheel, clutch release sleeeve, engine plate and transmission.

The early 1200 4-speed will work fine with an A14 if you drive it smoothly. But the A15 has a bit to much torque to be reliable. It may work for a long time, but it may give out. Chipped teeth is the normal problem.

If your 1200 already has the 56A 4-speed it is strong enough for an A15.

Peek under the car, on the right side of the gearbox for the letter 56A and you are golden:
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Or in this area (56A late ute super strong):
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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.

An A14 or low-torque A15 will be OK in front of an H145. A15 after 1981 is low torque.
While some club members have had their H145 last behind an A15, many have had it break. It is the ring & pinion gears (CWP) that break, not the axles.

For upgrades you can either: 1) Fit an H150 diff center into your 1200 housing. See H150 center swap or 2) Swap an entire rear axle assembly into your 1200. See Rear Axle Swaps.

Engine Mounts

The easiest thing to do is use simple flat plates to adapt the motor.

The most elegant way is to swap crossmembers. If you can find the right crossmember. For example: 1975 A12 with 1974-up crossmember. Or 1972 A12 with 1970-1973 crossmember.

1974-up engines (including all A14/A15 engines) 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:

Stock left-side mount in Datsun 1200, but Newer A12 engine. All it needs is a simple flat plate with two holes drilled in it. Alternatively, you could 1) use the 1974-up 1200 crossmember or 2) modify the crossmember or 3) modify the engine brackets.

Crossmember Swap

Be sure to get a matched set:

Late Engine + Late Engine mounting brackets + Late Engine Crossmember

Early Engine + Early Engine mounting brackets + Early Engine Crossmember

Early engines are 1967-1973, and late engines are 1974-up.

Swap the crossmember? 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.

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Early vs Late Engine crossmembers
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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.

Perhaps a 3mm difference.

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.

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

5mm higher from bottom of block

1. Remove this Late LH bracket:

2. 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:

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

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:

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.

154 mm: Early block front face to center of mount

189 mm: Revised block front face to center of mount

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.

Two types of right-side brackets:

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, instead of using adaper plates, 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.

custom engine mounts

Discussions and Details

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

full

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.

Three different RH mounts. Which is best for a swap?
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cheater_5 wrote up a detailed conversion here: Cheaters a15 into 1200 conversion
An A14 installation Mildman undertook has been quite significantly detailed at the following web link: Mildman's A14 Installation
There is also a technical article at the datsun1200.com site that discusses this installation too: Datsun1200.com Tech Section

Early Engine onto Late Crossmember

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

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.

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

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

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.

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.

Swap Notes

1200 wiring will reach either Distributor (under #1 or under #3)
Alternator fits on opposites sides. Late engines have right-side alternator.
- 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) wire as original.
- Newer engine may have an alternator marked S-L. If so, simple wiring mods can be done.
Radiator hoses are different for the original 1200 low-mount alternator.

HB210

North American B210 came with A14 fitted with mid-sump engine pan.

if swapping this HB210 engine into 1200, swap the pan and pickup tube with the newer B310 A14 pan and pickup tube.
If swapping an engine into a North America B210, see B210 Engine Swaps#North America

B310

B310 fits all A-series engines from 1974 on.

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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A-series Engine Swaps