From Datsun 1200 Wiki

The Hitachi DCH340 series carburetor is larger than the stock Datsun 1200 Hitachi DCH306 carburetor, yet runs smoother and makes more power than a Weber 32/36 Carburetor. They came as standard equipment on mid-to-late 1970s Datsun L-series engine, and Jet Kits for the A12 engine were available. It was first used on 1973 L16 and L18, and on all the L20Bs that followed.

 (http://datsun1200.com/modules/myalbum/photo.php?lid=15574) A12 Jet Kit

 (http://datsun1200.com/modules/myalbum/photo.php?lid=1992) DCH340 on A14 Engine

• Technical article comparing to Weber DGV and Hitachi DAF328 (L16) carburetors (http://dimequarterly.tierranet.com/articles/tech_carb_tuning_guide.html)
• DCH340 parts diagram (http://www.carburetorfactory.com/expvw29.html)
• Tercel Swap DCH340 (http://www.tercel4wd.com/forums/viewtopic.php?t=2826&sid=0100ee7c4579cbae2c61270a40f38b51)

  "The car has never run better, pulls strong (even with the AC on—a real miracle), and the gas mileage is back up."

CFM

Weber DGV (32/36): 235 to 330 cfm. Most are 270 cfm Hitachi DCH306: Hitachi DCH340:

NOTE: 270 CFM @ 3 inches mercury is equivalent to a 4-barrel type rating of 193 CFM (4-barrel carbs are rated at 1.5 inch mercury)

NOTE: an L20B revving at 6,000 RPM only needs 211 CFM 7,700 RPM requires 270 cfm with the 2-liter engine

Hitachi Carb Lineage

Hitachi DCx Series

• better venturis than the DAF series it replaced
• vacuum operated secondaries
• Used on Datsuns and 1973-1976 Honda Civic 1200/1250

Models

• DCG286: 28 mm secondary bore - Datsun 1000, A10 engine
• DCA306: 1967-1969 520 with J13 engine
• DCG306: 30 mm secondary bore - Datsun 1200, A12 engine, manual choke. Honda Civic.
• DCH306: 30 mm secondary bore - Datsun 1200, A12 engine, auto choke. Also used by A13, A14, A15
• DCR306: 1981-1982 A15, E15, E16
• DCH340: 34 mm secondary bore - Datsun 510, 610, 710, 620, 720. L16, L18
• DCH340 with high-speed enrichment system - L20B engine. Isuzu Chevrolet LUV
• DCR360: 1980 L20B, Z20
• DCR342: 1981 L20B, Z20 California, 1982 CA20 Stanza
• DCH342: 1981 L20B, Z20 non-California
• DCH328: 32 mm secondary bore -
• DCR384: 1983-1986 Z24 engine

DFx Series

• DFP306: 1981-1983 MPG Pulsur, MPG Sentra E15, E16
  • Also Geo 1985-1986 M/T 1.0 liter
• DFC328: 1983 Pulsur, Sentra E15, E16
• DCZ328: 1983 Pulsur, Sentra E15, E16
• DFE2832: 1984-1985 Pulsur, Sentra E15, E16
• DFP384: 1983-1986 Z24 engine

Hitachi DAF series - Solex-style primary venturi

• DAF328 - Most L16
  • Ford Courier
  • Also 1987-1988 Ford Ranger 2.0 (Mazda engine)