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Some Datsuns were fitted with sidedraft carburetors right from the factory. Usually fitted with twin Hitachi variable venturi carburetors which are very similar to S.U. (Skinners Union) carburettors from Britain. The Datsun 1200 GX models were fitted with twin Hitachi HJE38W 38 mm carburetors. Some Japan-market B210s were fitted with A12T or A14T engines which also used twin-Hitachi carbs. Many Datsun fans refer to the Hitachis sidedraughts as "SUs", so keep that in mind when you read information. It may be about the factory Hitachi sidedrafts, or it may be about the (non-Datsun) British SU sidedrafts.

Overview

Reportedly, Hitachi licensed the SU design, but I have yet to see a reference for that (Nissan manual, etc).

Datsun twin-carb setups used two basic Hitachi sizes:

38 mm (1-1/2 inch bore) on most cars
46 mm (1-7/8 inch bore) on Z-cars. These are too big for Nissan A engines (even if you use one) and reportedly the late model flat top 46s are a bad design.

Identification

Hitachi ID markings are inked (not stamped) onto the float bowl housing.

Other identifying features include shape of tops, type of fittings, etc.

Three Different Designs

Factory Hitachi setups for A-series engine include the A12GX, A12T and A14T types. These were fitted to JDM B110, B210 and Datsun Cherry vehicles. South Africa also sold many Twin-Carb B110s.

A12GX for B110 (1971-1973) - Extra Large Oval Ports (30 x 34.5 mm)
A12T for B210 (1974-1975) - Extra Large Oval Ports
A14T for B210 (1976-1978) - Standard Oval Ports (28 x 34 mm)

A12 GX Engine

The Datsun 1200 GX (Grand Luxe Twin-carb) models were always fitted with the A12 GX Engine. This engine featured a matched pair of left- and right- hand Hitachi HJE38W sidedraft carbs. These are the true "dome-top" Hitachis, already setup for performance. They can use standard SU needles so tuning it quite easy.

11041-H2300 HEAD ASSY-CYLINDER A12 GX B110

See main article A12GX Engine

Note: A12GX was not fitted with flat-top carburetors.

A12T Engine

See main article: Hitachi Twin Carb A12T

JDM 1973-1975 B210 GX models cam with A12S single-carb engines or the A12T twin-carb engine. While very similar to the A12 GX Engine, the A12T engine used flat-top Hitachis and a slightly different intake manifold with a few more fittings. These are decent carburetors and contrary to talk are not watered-down "emission carbs".

Flat-tops from A12T.

NOTE: B210 "GX" (Grand Luxury) refers to the car and does not necessarily mean the car included a twin-carb engine as the B110 GX did. While some 1973-1975 Japan-market B210 GX models did include the A12T engine, most were fitted with a single-carb (A12S) engine.

JDM Datsun Cherry (E10) models also used the A12T engine, including the famous Cherry X1-R vehicle.

A14T Engine

Starting in July 1976, the B120's A12T was replaced by the A14T. This corresponded with the B211 model change (B210 minor facelift). Some (but not all) GX models used the Twin-carb engine; even in Japan other 1976-1978 GX models used a single carb engine. Unlike the A12GX and A12T engines with their monster intake ports, the A14T used standard A14 oval ports (28x34 mm), which are smaller than A12GX ports (30x35mm). A14T used a single tube exhaust manifold (A12 twin-carb engines used twin-outlet exhaust manifold).

11041-M2460 HEAD ASSY-CYLINDER A14T

Datsun Cherry (F10) models with A14T engine also used the very same cylinder head.

A14T Manifold matches standard A14 gasket

One improvement over the A12GX engine is that the A14T uses a small thermostat where the water goes into the manifold

A14T engines used flat-top carbs, heavily modified from the A12 type Hitachis apparently to manage emission control.

Nissan B211 Parts catalog showing some GX models were fitted with single-carb (A14S) engine:

A14T Features:

Normal oval-ports (instead of the large GX size)
A lot of emission controls
EGR port on top of manifold
Throttle servo
Flat-top triangular-bell Hitachis
Automatic chokes (electric)
Vacuum ports on each end, top of manifold
No PCV valve fitting

Carb side:

4-bolt pattern on 3.5 in. circle
1.5 inch bore
Carb spacing approx 7-1/8 inch
Water ports at bottom

SU manifold is different:

Retro-fitting

For true bolt on experience, you will need a complete setup:

Intake manifold
Exhaust manifold (twin down-pipe cast headers). The clearance differently than regular manifolds
Two carbs
Fuel lines
Accelerator cable & linkage
Choke cables
Air cleaners

In general on a given manifold you can use SU, Zenith-Stromberg (ZS) or Hitachi sidedrafts, but note that the linkage, hose locations and air cleaner attachment will vary.

NOTE: The Hitachi sidedraught carbs are on the left side of the A-series engine. On a RHD car there is clearance aplenty, but on a LHD car fitting an air cleaner it a bit tricky. But this is more easily fitted to LHD than a twin-Weber setup.

Variations

Dome Tops vs Flat tops:

Dome Tops are early models
Flat Tops are 1974-up (from July 1973) some with emission controls

NOTE Linkage differs between different models.

38 mm

38 mm (1-1/2")

HJB

38 mm (1-1/2"):

HJB38W-1: 1963-1964 SP310 1500 Roadster G engine
HJB38W-3: May 1965-1967 Roadster SPL311-1600 (R16 engine), CSP311 Silvia

HJE

38 mm

HJE38W-1: 1964 DP410MTK (410 Bluebird)
16010-10615
- Used two right-hand carbs, with right-angle forward-facing fuel inlets
- Used twin-snorkel air cleaner, with dual interior right-angle air horns.

HJE38W-2: 1966 411 SS Bluebird (DR411)
16010-16710
HJE38W-3: 411 Bluebird 1600 (DP411MTK)
16010-15800, 16010-18810
- Used two right-hand carbs, with right-angle engine-facing fuel inlets
- Different mounting angle
- Same air cleaner as 410
- Used bar linkage, (similar to a twin Mikuni setup)

HJE38W: B110GTK, KB110GTK Datsun Sunny 1200 GX
16010-H2330 front
16010-H2331 rear
A12 GX from '70-Jul
16010-H2332 front
16010-H2333 rear
A12 GX from '71-11
16010-H2334 front
16010-H2335 rear
From '73-1
16010-H2336 front
16010-H2337 rear
- Fuel bowl outlets: Banjo fitting
- Fuel bowl inlets: Engine-facing nipples

HJE38W
16010-H2332 PE10 A12T front
16010-H2333 PE10 A12T rear
HJE38W-5C PE10 A12T (from '71-11)
16010-M0830 front
16010-M0850 rear
HJE38W-5E PE10 A12T (from '73-1)
16010-M0831 front
16010-M0851 rear
HJE38W-8A PE10 A12T (from '73-3)
16010-M0832 PE10 A12T front [flat tops]
16010-M0852 PE10 A12T rear [flat tops]

HJE38W-8 B210 A12T
16010-H5731 front [flat top]
16010-H5751 rear [flat top]
- OPTION hot air cleaner

Unknown Type 38mm

B210 A14T [Flat Tops, new type]
- Triangular shaped throttle plates

HJL/HTL

38mm

HJL38W-1A: 1969 P510 SSS [P510TK], CSS [KP510TK]
16010-22002, 16010-22004
- Fuel inlet, engine facing banjo
HJL38W-2A: P510 SSS, CSS OPTION
16010-22005
1971 510 SSS P510TK (1600), KP510TK, H510TK (1800), H510ATK, KH510ATK
- same fuel inlets as B110 GX
HJL38W-5 L14T circa 1972 PB110
- Fuel bowl outlets: upward pointing nipples
- Fuel bowl inlets: Engine-facing nipples angled up
- Fat air cleaner from 7110
1972 510 SSS
- Fat air cleaner
HTL28W-6: 1972-1973 610 twin carb ass'y
16010-U0800
HJL38W-6A: 1973 610 L16T, L18T (from '72-7)
16010-U0831 front [flat top]
16010-U0851 rear [flat top]
HTL38W-7: 1973 610 L16T, L18T (from '73-3)
16010-K1430 front [flat top]
16010-K1450 rear [flat top]
1975 610
16010-K1431 front [flat top]
16010-K1450 rear [flat top]
HJL38W-8 PB210 L14T [Flat Tops]
HJL38W-7 710 L16T [flat tops]
16010-K1430 front
16010-K1450 rear
HJL38W-7 710 (from '73-6)
16010-K1431 front
16010-K1451 rear

N510 1971 catalog
- 16010-N0410 L16T, 1800 SSS
- 16010-U0800 L16T
- 16010-U0831 L16T
- 16010-U0851 L16T
- 16010-A8700 1971 L18T, late 1600 SSS

46 mm

46 mm (~1-13/16)

HJL46W: ?
HJG46W: Roadster U20 (SRL311-2000)
HJG46W-3A: S30 (240Z) Manual Trans -0871
- HJG46W-R3A rear carb
- HJG46W-F3A front carb
HJG46W-4: S30 Automatic 0870-0871
1972 changed to water-heated carbs
HJG46W-8: S30 1972 manual trans
- HJG46W-R8B rear carb
- HJG46W-F8B front carb
HJG46W-9: S30 1972 auto trans
- HJG46W-R9A: rear carb
- HJG46W-F9A: front carb
HBM46W-1 1973-1974 (240Z & 260Z Flat Tops)

http://www.zparts.com/zptech/articles/mal_land/ml_sucarb2/SUcarb_111601b.htm

Parts Donors

A-series import engines from Japan
Datsun Competition setups
Datsun Roadsters: Reportedly, all Roadsters were fitted with Hitachis except the 2000 Roadster (2-liter engine) which came with Solex/Mikuni carbs.
Datsun 411 SSS (circa 1966)
Datsun 510 (1600) SSS
Datsun 610 (180B) SSS
Datsun 710 (160J) SSS

Damper Oil

The damper (aka dashpot) is oil-filled. Nissan recommended 20W or 10W30 Elephant Oil, but any brand of motor oil will work. Others have reported success with ATF (automatic transmission fluid), sewing machine oil (generally 10W), or motorcyle oil. The lighter oils tend to run the carb on the lean side.

Tuning

See main article: Hitachi Twin Carb Adjustment

Troubleshooting

Go here for lots of information: The Hitachi-SU Tech Pages - Troubleshooting.

References

Nissan Motorsports catalog (#99996-CAT98 and other years)
Nissan Schematic catalog (#99996-M8015)

Parts Suppliers

Nissan sells quite a few parts for the Hitachis
Z-Therapy sells parts and complete setups http://www.ztherapy.com
- Get the 510 SSS carb setup. The jetting is slightly different but otherwise they are the same
craigslist and other local sources (from time to time)
eBay from time to time

The parts although not common, are not rare in USA. Quite a few twin setups were found on import engines in the 1980s, and quite a few were purchased from Datsun Competition, so they can be found.

ZTherapy is in the USA, and always has them on hand.

Part Numbers

See:

Nissan Competition

From the 1984 Nissan Competition catalog.

GX/SU INDUCTION SYSTEM

The GX/SU induction system was a production line option on non-USA versions of the 1200 and B210. Requires use of GX cylinder head. The GX system can be adapted to virtually any A-series engine.

16010-H2336 38MM SU CARB (FRONT)
16010-H2337 38MM SU CARB (REAR)
14003-H2330 GX INTAKE MANIFOLD
11826-H2300 BLOCK TO MANIFOLD HOSE
14035-H2300 MANIFOLD GASKET
14330-H2303 GX HEAT SHIELD (1)
16031-H2300 OVERFLOW TUBE/FRONT
16031-H2301 OVERFLOW TUBE/REAR
16174-H2300 INSULATOR (2)
16175-A5100 INSULATOR GASKET (2)
16361-H2300 THROTTLE SHAFT ASSY
16376-H2300 ACCELERATOR CABLE BRACKET
17523-H2302 FUEL TUBE (1)
18410-H2302 CHOKE CABLE (1)

Photo Index

See:

Retrieved from "http://datsun1200.com/modules/mediawiki/index.php?title=Hitachi_Twin_Carb"

Hitachi Twin Carb

Contents

Overview

Identification

Three Different Designs

A12 GX Engine

A12T Engine

A14T Engine

Retro-fitting

Variations

38 mm

HJB

HJE

HJL/HTL

46 mm

Parts Donors

Damper Oil

Tuning

Troubleshooting

References

Parts Suppliers

Part Numbers

Nissan Competition

Links

Photo Index