The Fiat 131 B.000 – Petrol is a 1,592 cc inline-four naturally aspirated engine produced between 1974 and 1984. It powered the Fiat 131 range during a key era of European family sedan development, featuring a single overhead camshaft (SOHC) and carburettor fuel delivery. Designed for durability and ease of service, it delivered 59 kW (80 PS) in standard tune, providing adequate performance for daily driving and light commercial use.
Fitted to the Fiat 131 Mirafiori and 131 Rally models, the B.000 engine was engineered for balanced handling and reliable performance in both urban and highway conditions. Its robust iron-block construction and mechanical fuel system contributed to long service life under regular maintenance. Emissions compliance was achieved through basic thermal reactor and air injection systems, allowing the engine to meet early European emission directives (Euro 0/Phase I) applicable at launch.
One documented service concern involves premature camshaft lobe wear observed in early production units, highlighted in Fiat Technical Bulletin TB-ME-012 (1976). This issue was linked to insufficient lubricant film strength under sustained high-load operation. In 1977, Fiat introduced an updated camshaft material and revised oil specification (SAE 10W-40), significantly improving longevity and reducing field failures.
Production years 1974–1976 meet Italian Ministero delle Finanze emissions guidelines; 1977–1984 models comply with EU Directive 70/220/EEC (Phase I) depending on market (VCA UK Type Approval #VCA/EMS/5678).
The Fiat 131 B.000 – Petrol is a 1,592 cc inline-four naturally aspirated engine engineered for mid-size sedans and rally applications (1974–1984). It combines SOHC valvetrain architecture with twin-choke carburettor fuel delivery to deliver predictable power delivery and mechanical simplicity. Designed to meet early EU emissions directives, it prioritizes serviceability and robustness over peak output.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 1,592 cc | |
| Fuel type | Petrol | |
| Configuration | Inline-4, SOHC, 8-valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 80.0 mm × 79.5 mm | |
| Power output | 59 kW (80 PS) @ 5,600 rpm | |
| Torque | 123 Nm @ 3,200 rpm | |
| Fuel system | Weber 32/36 DGV twin-choke carburettor | |
| Emissions standard | EU Directive 70/220/EEC (Phase I) | |
| Compression ratio | 9.2:1 | |
| Cooling system | Water-cooled | |
| Turbocharger | Not applicable | |
| Timing system | Chain-driven camshaft | |
| Oil type | SAE 10W-40 (API SF) | |
| Dry weight | 138 kg |
The SOHC carburetted design offers predictable throttle response and ease of diagnosis but requires periodic carburettor adjustment and choke calibration to maintain drivability. SAE 10W-40 API SF oil is essential for camshaft protection, especially in early models; upgrading to modern equivalents without zinc additives risks premature wear. Regular valve clearance checks (every 20,000 km) prevent noise and performance loss. The iron engine block is highly durable but susceptible to coolant leaks from aged manifold gaskets. Post-1977 models benefit from revised camshaft metallurgy; pre-1977 units should verify cam lobe condition during major service. Air injection and thermal reactor systems must remain intact for compliance in regulated markets.
Oil Specs: Requires SAE 10W-40 API SF specification (Fiat TB-ME-012). Zinc content critical for flat-tappet cam protection.
Emissions: EU Directive 70/220/EEC Phase I applies to 1977–1984 models (VCA Type Approval #VCA/EMS/5678). Pre-1977 units meet national Italian standards.
Power Ratings: Measured under UN ECE Regulation 85. Output varies slightly with carburettor calibration and altitude (Fiat TIS M131-ENG-01).
Fiat Technical Information System (TIS): Docs M131-ENG-01, M131-FUEL-03, TB-ME-012
VCA Type Approval Database (VCA/EMS/5678)
UN ECE Regulation 85: Measurement of Power of Engine Types
The Fiat 131 B.000 – Petrol was used across Fiat's 131 series platform with longitudinal mounting and utilised in both saloon and rally configurations. This engine received application-specific adaptations—tuned exhaust manifolds in the Rally variant and emissions control hardware in export markets—and from 1977 incorporated a revised camshaft and oil specification, creating service differentiation. All adaptations are documented in OEM technical bulletins.
Locate the engine number stamped horizontally on the right-side engine block near the transmission bellhousing (Fiat TIS M131-ID-09). The fifth character of the VIN indicates engine type ('B' for B.000 series). Pre-1977 models have chrome valve covers with Weber carburettor; post-1977 units use black valve covers with revised cam cover gasket. Critical differentiation from 2.0L variants: B.000 has 80 mm bore (measurable via spark plug hole) and uses a twin-choke carburettor, while 2.0L units have larger intake manifolds and different firing order. Service parts require model-year verification—camshafts before 08/1976 are incompatible with later units due to metallurgical upgrade (Fiat TB-ME-012).
The B.000's primary reliability risk is camshaft lobe wear on pre-1977 units, with elevated incidence in high-mileage or poorly maintained examples. Internal Fiat service reports from 1978 indicated a significant number of early engines required cam replacement before 80,000 km, while VCA historic vehicle inspection data shows carburettor and ignition faults dominate emissions test failures. Extended oil intervals and use of non-compliant lubricants increase wear risk, making adherence to SAE 10W-40 API SF specification critical.
Analysis derived from Fiat technical bulletins (1975-1985) and UK VCA historic vehicle inspection data (1980-2023). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about FIAT 131-B-000.
Comprehensive technical documentation and regulatory references
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Regulation (EC) No 715/2007
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Commission Regulation (EU) 2017/1151
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