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[Datsun 1200 encyclopedia]

Hitachi Twin Carb

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Revision as of 05:46, 26 December 2008
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== A12 GX Engine == == A12 GX Engine ==
-The Datsun 1200 GX (Grand Luxe Twin-carb) models were fitted with the [[A12 GX Engine]]. This 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.+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 11041-H2300 HEAD ASSY-CYLINDER A12 GX B110
Line 30: Line 30:
== A12T Engine == == A12T Engine ==
-[[JDM]] 1974-1975 B210 GX models had the A12T twin-carb engine (also known as GX-T). While very similar to the A12 GX Engine, the A12T engine used different flattop Hitachis and a slightly different intake manifold with a few more fittings. Reportedly, these are decent carburetors that only need a [http://www.jetlink.net/~okayfine/su/tunacan.html few simple modifications]. The B210's A12T cylinder head is identical the A12 GX head, except the passage for old-style rocker oiling may not be drilled in B210 heads.+[[JDM]] 1973-1975 B210 GX models had the A12T twin-carb engine. While very similar to the A12 GX Engine, the A12T engine used different flattop Hitachis and a slightly different intake manifold with a few more fittings. Reportedly, these are decent carburetors that only need a [http://www.jetlink.net/~okayfine/su/tunacan.html few simple modifications]. The B210's A12T cylinder head is identical the A12 GX head, except the passage for old-style rocker oiling may not be drilled in B210 heads.
11041-H5702 HEAD ASS'Y-cylinder A12T 11041-H5702 HEAD ASS'Y-cylinder A12T
Line 37: Line 37:
-NOTE: B210 "GX" refers to the car only and does not necessarily mean the car included a twin-carb engine as the B110 GX did. While Japan-market B210 GX did include the A12T engine, however outside Japan most B210 GX models were fitted with a single-carb (A12S) engine.+NOTE: B210 "GX" refers to the car and does not necessarily mean the car included a twin-carb engine as the B110 GX did. While 1973-1975 Japan-market B210 GX models did include the A12T engine, outside Japan most B210 GX models were fitted with a single-carb (A12S) engine.
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== A14T Engine == == A14T Engine ==
-Starting around 1976, the B120's A12T was phased out and the A14T started. 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).+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 11041-M2460 HEAD ASSY-CYLINDER A14T
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* One improvement over the A12GX engine is that the A14T uses a small thermostat where the water goes into the manifold * One improvement over the A12GX engine is that the A14T uses a small thermostat where the water goes into the manifold
-A14T engines use flat-top carbs, probably the same as L18SSS engines, heavily modified from the A12 type Hitachis, apparently to manage emission control. +A14T engines used flat-top carbs, heavily modified from the A12 type Hitachis apparently to manage emission control.
LOOK! [http://ddgonzal.members.winisp.net/A14T A14T manifold photo gallery] LOOK! [http://ddgonzal.members.winisp.net/A14T A14T manifold photo gallery]
* http://ddgonzal.members.winisp.net/A14T/_thDSC03724.jpg * http://ddgonzal.members.winisp.net/A14T/_thDSC03724.jpg
 +
 +
 +Nissan B211 Parts catalog showing some GX models were fitted with single-carb (A14S) engine:
 +* ][http://datsun1200.com/modules/myalbum/photo.php?lid=18272 http://datsun1200.com/modules/myalbum/photos/thumbs/18272.jpg]

Revision as of 06:35, 26 December 2008

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.

13428.jpg 18247.jpg

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.


Contents

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.

13415.jpg

  • 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

8355.jpg 1973.jpg


A12T Engine

JDM 1973-1975 B210 GX models had the A12T twin-carb engine. While very similar to the A12 GX Engine, the A12T engine used different flattop Hitachis and a slightly different intake manifold with a few more fittings. Reportedly, these are decent carburetors that only need a few simple modifications. The B210's A12T cylinder head is identical the A12 GX head, except the passage for old-style rocker oiling may not be drilled in B210 heads.

11041-H5702 HEAD ASS'Y-cylinder A12T 

776.jpg


NOTE: B210 "GX" refers to the car and does not necessarily mean the car included a twin-carb engine as the B110 GX did. While 1973-1975 Japan-market B210 GX models did include the A12T engine, outside Japan most B210 GX models 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.

11041-M0801 HEAD ASSY-CYLINDER A12T

The M08 head looks like the A12GX head. Most likely the fittings and accessory bolts are slightly different from the A12GX version.


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

1933.jpg 13406.jpg11824.jpg

  • 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.


LOOK! A14T manifold photo gallery
* _thDSC03724.jpg


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

  • ]18272.jpg


A14T Features:

  • EGR port
  • Flat-top triangular-bell Hitachis
  • 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

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 with emission controls


38 mm

  • HJB38W: Roadster R engine (SPL311-1600)
  • HJB38W-3: Roadster with G engine, also 1968 R engine)
  • HJE38W: B110
  • HJL38W6: 510 L16 & L18

46 mm

  • HJG46W: Roadster U20 (SRL311-2000)

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

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

Troubleshooting

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

References

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


Parts Suppliers

  • 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:


Links

Photo Index

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