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| [[A12|A12T]] is the twin carb engine fitted to Datsun Sunny [[B210]] and Nissan Cherry PE10. It uses the [[Hitachi Twin Carb]] system, dual 38mm Hitachi sidedrafts. These mainly differ from the [[A12GX Engine]] Hitachis in that they are have a new idle speed and idle mixture system. They can be easily distinguished by their flat tops. | [[A12|A12T]] is the twin carb engine fitted to Datsun Sunny [[B210]] and Nissan Cherry PE10. It uses the [[Hitachi Twin Carb]] system, dual 38mm Hitachi sidedrafts. These mainly differ from the [[A12GX Engine]] Hitachis in that they are have a new idle speed and idle mixture system. They can be easily distinguished by their flat tops. | ||
| + | {{Hitachi Twin Carb Navbox}} | ||
| = Overview = | = Overview = | ||
| [[JDM]] 1973-1975 B210 GX models had either an A12S (single-carb) or optional A12T (twin-carb) engine. While the A12T is very similar to the A12 GX Engine, it used different flattop Hitachis and a slightly different intake manifold with a few more fittings. These are good carburetors that are not jetted leaner, but instead have a closed fuel bowl vent system. They are almost identical to the dome-top carburetors except for the IMS fittings on the top of the carbs. They total system (inlet manifold and hoses) is more complicated to allow idle mixture and speed adjustments and capture all the gasoline fumes into the air cleaner. | [[JDM]] 1973-1975 B210 GX models had either an A12S (single-carb) or optional A12T (twin-carb) engine. While the A12T is very similar to the A12 GX Engine, it used different flattop Hitachis and a slightly different intake manifold with a few more fittings. These are good carburetors that are not jetted leaner, but instead have a closed fuel bowl vent system. They are almost identical to the dome-top carburetors except for the IMS fittings on the top of the carbs. They total system (inlet manifold and hoses) is more complicated to allow idle mixture and speed adjustments and capture all the gasoline fumes into the air cleaner. | ||
| - | |||
| - | [http://datsun1200.com/modules/myalbum/photo.php?lid=776 http://datsun1200.com/uploads/photos/776.jpg] | ||
| JDM Datsun Cherry (E10) models also used the A12T engine, including the famous Cherry X1-R vehicle. | JDM Datsun Cherry (E10) models also used the A12T engine, including the famous Cherry X1-R vehicle. | ||
| - | == Competition Flat-Tops == | + | {{Photo2|10.jpg}} {{Photo2|11.jpg}} {{Photo2|12.jpg}} |
| - | NOTE: Competition versions of flat-tops do not have IMS. | + | |
| - | They are simply the old style carbs with the new tops. | + | |
| - | + | ||
| - | Datsun Competition ([[Nissan Competition]]) sold a open-vented, non-IMS, system: | + | |
| - | <br>[http://datsun1200.com/modules/myalbum/photo.php?lid=7554 http://datsun1200.com/uploads/thumbs/7554.jpg] | + | |
| - | <br>Supplied with simple vent tubes. Production A12T vents the carburetors to the air cleaner. | + | |
| = Idle Mixture System = | = Idle Mixture System = | ||
| Ummm... smells good, and works good too. JDM non-competition (stock) Hitachi sidedraft flat-top carburetors come with an advanced Idle Mixture System (IMS), for fine tuning of the idle mixture. | Ummm... smells good, and works good too. JDM non-competition (stock) Hitachi sidedraft flat-top carburetors come with an advanced Idle Mixture System (IMS), for fine tuning of the idle mixture. | ||
| - | [http://datsun1200.com/modules/myalbum/photo.php?lid=1132 Thick hoses]: Idle Mixture System (IMS) | + | [http://datsun1200.com/modules/myalbum/photo.php?lid=1132 Album]: Thick hoses are for Idle Mixture System (IMS) |
| <br><img size=400>http://datsun1200.com/uploads/photos/1132.jpg</img> | <br><img size=400>http://datsun1200.com/uploads/photos/1132.jpg</img> | ||
| - | [http://datsun1200.com/modules/myalbum/photo.php?lid=23191 Idle Mixture System] | + | [http://datsun1200.com/modules/myalbum/photo.php?lid=23191 Album]: Idle Mixture System |
| <br><img size=400>http://datsun1200.com/uploads/photos/23191.jpg</img> | <br><img size=400>http://datsun1200.com/uploads/photos/23191.jpg</img> | ||
| - | [http://datsun1200.com/modules/myalbum/photo.php?lid=21385 IMS body] with Mixture Screw | + | [http://datsun1200.com/modules/myalbum/photo.php?lid=21385 Album]: IMS body with Mixture Screw<div Title="click 'Album' to view comments" style="width:400px; border:thin solid black;"><img size=400>http://datsun1200.com/uploads/photos/21385.jpg</img></div> |
| - | <br><img size=400>http://datsun1200.com/uploads/photos/21385.jpg</img> | + | |
| == Adjustments == | == Adjustments == | ||
| Line 43: | Line 35: | ||
| # Lean out Mixture until speed drops to 725 rpm | # Lean out Mixture until speed drops to 725 rpm | ||
| - | [http://datsun1200.com/modules/myalbum/photo.php?lid=21386 Green]: Hoses to air cleaner (including the curved IMS hose) | + | <br>[http://datsun1200.com/modules/myalbum/photo.php?lid=21386 Album]<div Title="click 'Album' to view comments" style="width:400px; border:thin solid black;"><img size=400>http://datsun1200.com/uploads/photos/21386.jpg</img>Green: Hoses to air cleaner (including the curved IMS hose) |
| - | <br><img size=400>http://datsun1200.com/uploads/photos/21386.jpg</img> | + | Blue: Fuel lines to fuel bowls |
| - | <br>Blue: Fuel lines to fuel bowls | + | Red: Idle speed system (air bypass system), connects to IMS body vents</div> |
| - | <br>Red: Idle speed system (air bypass system), connects to IMS body vents | + | |
| - | Blue: Fuel bowl vent lines | + | <br>[http://datsun1200.com/modules/myalbum/photo.php?lid=21387 Album]<div Title="click 'Album' to view comments" style="width:400px; border:thin solid black;"><img size=400>http://datsun1200.com/uploads/photos/21387.jpg</img> |
| - | <br>[http://datsun1200.com/modules/myalbum/photo.php?lid=21387 Green]: IMS inner vent line (to Air Cleaner) | + | Blue: Fuel bowl vent lines |
| - | <br><img size=400>http://datsun1200.com/uploads/photos/21387.jpg</img> | + | |
| - | <br>Red: IMS (Idle Mixture) | + | Green: IMS inner vent line (to Air Cleaner) |
| + | Red: IMS (Idle Mixture)</div> | ||
| + | |||
| + | = Competition Flat-Tops = | ||
| + | Datsun Competition (Nissan Competition) sold a open-vented, non-IMS, twin carb system. | ||
| + | |||
| + | See main article: [[Hitachi_Twin_Carb#Nissan_Competition|Competition Carburetors]] | ||
| + | |||
| + | http://datsun1200.com/uploads/thumbs/7554.jpg | ||
| + | |||
| + | {{quote|text=NOTE: Competition versions of flat-tops do not have IMS. They are simply the old style carbs with the new tops.}} | ||
| + | |||
| + | {{quote|text=Competition flat-tops are Similar (or the same) as the Datsun 810 SSS twin carbs (200B or Euro 810 carbs).}} | ||
| - | {{Hitachi Twin Carb Navbox}} | ||
| [[Category:Hitachi Twin Carb]] | [[Category:Hitachi Twin Carb]] | ||
Current revision
A12T is the twin carb engine fitted to Datsun Sunny B210 and Nissan Cherry PE10. It uses the Hitachi Twin Carb system, dual 38mm Hitachi sidedrafts. These mainly differ from the A12GX Engine Hitachis in that they are have a new idle speed and idle mixture system. They can be easily distinguished by their flat tops.
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Contents |
[edit]
Overview
JDM 1973-1975 B210 GX models had either an A12S (single-carb) or optional A12T (twin-carb) engine. While the A12T is very similar to the A12 GX Engine, it used different flattop Hitachis and a slightly different intake manifold with a few more fittings. These are good carburetors that are not jetted leaner, but instead have a closed fuel bowl vent system. They are almost identical to the dome-top carburetors except for the IMS fittings on the top of the carbs. They total system (inlet manifold and hoses) is more complicated to allow idle mixture and speed adjustments and capture all the gasoline fumes into the air cleaner.
JDM Datsun Cherry (E10) models also used the A12T engine, including the famous Cherry X1-R vehicle.
[edit]
Idle Mixture System
Ummm... smells good, and works good too. JDM non-competition (stock) Hitachi sidedraft flat-top carburetors come with an advanced Idle Mixture System (IMS), for fine tuning of the idle mixture.
Album: Thick hoses are for Idle Mixture System (IMS)
Album: Idle Mixture System
[edit]
Adjustments
Idle mixture (IMS) is possible with the new flat-top Hitachi design.
- First of all, check the ignition timing and set it correctly
- Next, check the float levels. Nothing will work correctly if this is off
- Check oil damper level, and top off with 10W-30 if needed
- Loosen balance adjusting screw completely
- Set idle speed to 750 rpm by turning idle speed screw
- Clockwise: speed decreases
- Anti-clockwise: speed increase
- Synchronize the twin carbs by turning Balance screw
- Turn Mixture screw back and forth until best lean idle is achieved
- Reset idle speed to 750 rpm
- Lean out Mixture until speed drops to 725 rpm
Album
Green: Hoses to air cleaner (including the curved IMS hose)
Blue: Fuel lines to fuel bowls
Red: Idle speed system (air bypass system), connects to IMS body ventsAlbum
Blue: Fuel bowl vent lines
Green: IMS inner vent line (to Air Cleaner)
Red: IMS (Idle Mixture)[edit]
Competition Flat-Tops
Datsun Competition (Nissan Competition) sold a open-vented, non-IMS, twin carb system.
See main article: Competition Carburetors
NOTE: Competition versions of flat-tops do not have IMS. They are simply the old style carbs with the new tops.
Competition flat-tops are Similar (or the same) as the Datsun 810 SSS twin carbs (200B or Euro 810 carbs).