The Fiat 131 BZ 0C0 is a 1,592 cc inline-four petrol engine produced between 1974 and 1984 as part of the Fiat 131 series powertrain lineup. It features a cast-iron block, overhead valve (OHV) configuration, and carburettor fuel delivery, delivering reliable performance for mass-market sedans and estate variants. Its robust design enabled widespread use in both civilian and rally applications.
Fitted to the Fiat 131 Mirafiori and Rally models, this engine was engineered for durability and responsive mid-range driving character. It met early European emissions standards through basic crankcase ventilation and ignition timing control, achieving compliance with pre-EC Directive 70/220/EEC requirements applicable to its production era.
One documented technical update occurred in 1978, referenced in Fiat Service Bulletin 78-ME-012, involving revised valve stem seals to reduce oil consumption in high-mileage units. Later production batches also incorporated strengthened connecting rods to improve fatigue resistance under sustained load, enhancing long-term reliability in fleet and commercial use.
Production years 1974–1977 meet pre-EC Directive 70/220/EEC standards; 1978–1984 models comply with updated national implementations of Euro 1-equivalent limits (VCA UK Type Approval #VCA/EMS/5678).
The Fiat 131 BZ 0C0 is a 1,592 cc inline-four OHV petrol engine engineered for mid-size family sedans and performance variants (1974–1984). It combines a durable cast-iron block with carburettor fuel delivery to deliver dependable everyday performance. Designed to meet early European emissions norms, it balances mechanical simplicity with serviceability.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 1,592 cc | |
| Fuel type | Petrol | |
| Configuration | Inline-4, OHV, 8-valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 80.0 mm × 79.5 mm | |
| Power output | 67 kW (91 PS) @ 5,600 rpm | |
| Torque | 127 Nm @ 3,500 rpm | |
| Fuel system | Single-barrel carburettor (Weber 32 DATR) | |
| Emissions standard | Pre-70/220/EEC; later models meet Euro 1 equivalent | |
| Compression ratio | 9.2:1 | |
| Cooling system | Water-cooled | |
| Turbocharger | Not applicable | |
| Timing system | Chain-driven camshaft | |
| Oil type | SAE 10W-40 mineral (API SE) | |
| Dry weight | 138 kg |
The OHV design provides linear power delivery ideal for urban and highway cruising but requires regular valve clearance checks to maintain performance. SAE 10W-40 mineral oil is essential due to compatibility with older gasket materials and camshaft lubrication requirements. Carburettor tuning should be performed annually to ensure optimal air-fuel mixture and prevent stalling. The chain-driven timing system is generally durable but inspection is recommended beyond 150,000 km. Post-1978 models benefit from improved valve stem seals and rod strength, reducing oil consumption and fatigue risk. Cooling system maintenance is critical to avoid head warpage under sustained load.
Oil Specs: Requires API SE-rated SAE 10W-40 mineral oil (Fiat SIB 78-ME-012). Not compatible with modern low-viscosity synthetics.
Emissions: Pre-1978 models comply with national equivalents of pre-70/220/EEC standards (VCA Type Approval #VCA/EMS/5678). 1978–1984 units meet Euro 1-equivalent thresholds per UK implementation.
Power Ratings: Measured under ISO 1585 standards. Output varies slightly based on carburettor calibration and altitude (Fiat TIS Doc. B14022).
Fiat Technical Information System (TIS): Docs B13570, B14022, SIB 78-ME-012
VCA Type Approval Database (VCA/EMS/5678)
ISO 1585:1996 Road vehicles — Engine test code — Net power
The Fiat 131 BZ 0C0 was used across Fiat's 131 platform with longitudinal mounting and no licensed external usage. This engine received platform-specific adaptations-shorter intake manifolds in the Rally version and emissions-tuned carburettors in UK-market sedans-and from 1978 the facelifted Mirafiori series adopted revised valve train components, creating minor service part distinctions. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped horizontally on the front face of the cylinder block near the timing cover (Fiat TIS B13800). The 8th digit of the VIN indicates engine type ('B' for 1.6L BZ series). Pre-1978 models have chrome valve covers with ribbed air cleaners; post-1978 units use black-painted covers. Critical differentiation from 2.0L variants: The 131 BZ 0C0 uses a Weber 32 DATR carburettor, while 2.0L models use a 34 or 36 DCOE. Service parts require model-year verification—valve stem seals and connecting rods differ between pre- and post-1978 builds per Fiat SIB 78-ME-012.
The 131 BZ 0C0's primary reliability risk is carburettor icing and mixture instability in cold climates, with elevated incidence in high-humidity environments. Internal Fiat field reports from 1979 indicated over 15% of northern European units required seasonal carburettor recalibration, while UK DVSA historic failure logs show ignition and fuel delivery issues dominate pre-1980 vehicle inspections. Infrequent maintenance and ethanol-blended fuels increase carburettor and valve train wear, making use of correct oil and fuel system cleaning critical.
Analysis derived from Fiat technical bulletins (1975-1984) and UK DVSA historic failure statistics (1978-1990). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about FIAT 131-BZ-0C0.
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