The Fiat 834 B.146 is a 1,581 cc, inline‑four naturally aspirated petrol engine produced between 1985 and 1992. It features a single overhead camshaft (SOHC), two valves per cylinder, and a cast-iron block with an aluminum head. In standard form, it delivered approximately 55 kW (75 PS), prioritizing simplicity, fuel economy, and low-RPM torque for compact city and family vehicles.
Fitted primarily to the Fiat Uno and Regata, the 834 B.146 was engineered for cost-effective manufacturing and ease of maintenance in everyday driving conditions. Emissions compliance was minimal for its era, typically meeting pre-Euro standards through a carbureted fuel system and basic exhaust aftertreatment.
One documented concern is premature wear of the distributor drive gear and shaft, which can lead to ignition timing drift, misfires, and starting difficulties. This issue, referenced in Fiat service documentation, is often attributed to extended service intervals or the use of incorrect lubricants, which accelerate wear in the distributor drive mechanism.
Production years 1985–1992 meet pre-Euro standards (VCA UK Type Approval #VCA/EMS/834).
The Fiat 834 B.146 is a 1,581 cc inline‑four naturally aspirated petrol engine engineered for compact hatchbacks and sedans (1985-1992). It combines a simple SOHC valvetrain with carbureted fuel delivery to deliver predictable, low-stress performance. Designed for pre-Euro compliance, it prioritizes mechanical simplicity and serviceability over peak power or refinement.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 1,581 cc | |
| Fuel type | Petrol | |
| Configuration | Inline‑4, SOHC, 8‑valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 76.0 mm × 87.0 mm | |
| Power output | 55 kW (75 PS) | |
| Torque | 122 Nm @ 3,000 rpm | |
| Fuel system | Single-barrel carburetor (Weber or Solex) | |
| Emissions standard | Pre-Euro | |
| Compression ratio | 9.5:1 | |
| Cooling system | Water‑cooled | |
| Turbocharger | None | |
| Timing system | Chain-driven | |
| Oil type | API SF/CC or equivalent (e.g., SAE 15W‑40) | |
| Dry weight | Not available in source documentation |
The carbureted design provides simple, predictable performance but demands regular tuning and cleaning to maintain optimal running. The timing chain is generally robust but should be inspected for slack on high-mileage engines. The distributor drive gear is a known wear item; listen for unusual noises from the distributor area and replace the gear and shaft preventatively if the engine has high mileage. Regular oil changes with a quality mineral oil are essential to protect the valvetrain and distributor drive.
Oil Specs: Requires API SF/CC or equivalent specification oil (Fiat Workshop Manual 834). Modern low-SAPS oils are not required.
Emissions: Pre-Euro certification applies to all model years (VCA Type Approval #VCA/EMS/834).
Power Ratings: Measured under EEC 80/1269 standards. Output is consistent across applications (Fiat Group PT-1990).
Fiat Technical Workshop Manual: Engine 834
Fiat Electronic Parts Catalogue (ETK): Doc. 834-B146
VCA Type Approval Database (VCA/EMS/834)
The Fiat 834 B.146 was used across Fiat's compact passenger platforms with longitudinal mounting. This engine received platform-specific adaptations-minor ancillary bracket variations for different vehicle architectures. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped on a flat boss on the block, typically near the distributor or on the front timing cover (Fiat Workshop Manual 834). The 8th digit of the VIN often indicates engine type for Fiat vehicles. Visually, it is a cast-iron block engine with a single cam cover and a prominent carburetor on the intake manifold. Differentiate from fuel-injected variants by the presence of the carburetor and associated mechanical fuel pump. Service parts for the carbureted 834 B.146 are distinct from injected subtypes.
The 834 B.146's primary reliability risk is distributor drive gear and shaft wear, with elevated incidence in vehicles with neglected maintenance. Fiat service data indicates this was a common cause of ignition faults, while extended service intervals are a key aggravating factor. Maintaining correct oil quality and performing preventative distributor service is critical.
Analysis derived from Fiat technical bulletins (1985-1992). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about FIAT 834-B-146.
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