Basic Identity

What the model codes mean

• Weber model numbers start with one or two numbers that relate to the venturi (throttle bore) sizes in millimeters — e.g., 28/30 means two venturi sizes (smaller and larger) for progressive fueling. 32 refers to a single 32 mm venturi application. The trailing letters (like DHTA or DATRA) are Weber’s internal design codes that differentiate specific carb designs and variants — often indicating things like choke type, linkage, or application version — but there’s no simple dictionary of letter meanings from Weber itself.

Two distinct carburetor types

• 28/30DHTA ? a progressive two-venturi downdraft Weber carb with a smaller and larger throat.

• 32 DATRA ? a 32 mm single-bore downdraft Weber carb.
  Both are OEM style Weber units rather than performance-race only carbs.

Applications & Fitment

These carbs weren’t random aftermarket pieces — they were factory or dealer-approved Webers for European 4-cylinder cars in the ’70s and early ’80s:

28/30DHTA

• Commonly fitted to Fiat 128 / X1/9 (1.3 L) engines in the mid-1970s.

• Also available on some Lancia 4-cylinder models around the same era.

• Typical part numbers stamped or tagged include variants like 28/30DHTA5/…, 28/30DHTA7/…, etc.

32 DATRA

• Used on slightly larger-displacement SOHC engines — e.g., later Fiat X1/9s and 128s with larger head and manifold, and some Lancia Beta variants.

• It was basically the next step up in size from the 28/30 carb for more airflow/fuel capacity.

Weber 26/34 DHSA

What it is:
A progressive 2-venturi downdraft Weber carburetor used mainly as an OEM carb on small-displacement European engines.

Key traits:

• 26 mm primary venturi

• 34 mm secondary venturi

• Progressive throttle plates (small barrel opens first, large opens later)

• Manual or automatic choke depending on variant

• Designed for low-to-mid displacement engines (typically 1.0–1.3L)

Typical factory applications:

• Fiat 127, 128, Panda, Uno (various SOHC engines)

• Some Lancia small-displacement installs

• Also used as a Weber replacement unit on older Solex or Zenith setups

Design purpose:
Fuel economy + decent part-throttle performance for small engines. These were Weber’s “daily driver” economy carbs.

Weber 30 DIC

What it is:
A single-venturi downdraft Weber carb used widely across European cars in the 1960s-1970s.

Key traits:

• 30 mm main venturi

• Single-barrel carb

• Simple, reliable, and easy to tune

• Came in multiple variants (DIC, DIC1, DIC32, etc.)

Typical factory applications:

• Fiat 850, 127 early models, 128 early models

• Some SEAT variants

• Small marine and industrial versions exist

Design purpose:
A dead-simple, low-maintenance carb feeding small engines that didn’t require progressive barrels.

In a Nutshell