The Fiat 131 FZ is a 1,995 cc inline-four petrol engine produced between 1974 and 1984 as part of the Fiat 131 series. It features a cast-iron block, overhead valve (OHV) configuration, and twin-choke carburettor fuel delivery, delivering increased torque and smooth mid-range performance for larger sedan and estate applications.
Fitted primarily to the Fiat 131 Mirafiori 2.0L and Supermirafiori variants, this engine was engineered for enhanced drivability and improved load-carrying capability over the 1.6L units. Emissions control was achieved through basic crankcase ventilation and ignition timing adjustments, meeting pre-EC Directive 70/220/EEC standards applicable during its initial production period.
One documented technical update occurred in 1979, referenced in Fiat Service Bulletin 79-ME-018, involving revised cylinder head gasket material to reduce head warping under sustained load. Later production batches also incorporated upgraded valve springs to improve high-RPM stability, enhancing durability in both private and fleet 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/6789).
The Fiat 131 FZ is a 1,995 cc inline-four OHV petrol engine engineered for mid-size family sedans and higher-trim variants (1974–1984). It combines a durable cast-iron block with twin-choke carburettor fuel delivery to deliver enhanced torque and responsive performance. Designed to meet early European emissions norms, it balances mechanical robustness with serviceability.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 1,995 cc | |
| Fuel type | Petrol | |
| Configuration | Inline-4, OHV, 8-valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 84.0 mm × 90.0 mm | |
| Power output | 77 kW (105 PS) @ 5,400 rpm | |
| Torque | 152 Nm @ 3,200 rpm | |
| Fuel system | Twin-choke carburettor (Weber 36 DCF) | |
| Emissions standard | Pre-70/220/EEC; later models meet Euro 1 equivalent | |
| Compression ratio | 9.0:1 | |
| Cooling system | Water-cooled | |
| Turbocharger | Not applicable | |
| Timing system | Chain-driven camshaft | |
| Oil type | SAE 10W-40 mineral (API SE) | |
| Dry weight | 142 kg |
The OHV design provides strong mid-range torque ideal for highway cruising and loaded driving 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. Twin-choke carburettor tuning should be performed annually to ensure balanced air-fuel mixture and prevent hesitation. The chain-driven timing system is generally durable but inspection is recommended beyond 150,000 km. Post-1979 models benefit from improved head gasket integrity and valve spring performance, reducing head warping and float risk. Cooling system maintenance is critical to avoid thermal stress under sustained load.
Oil Specs: Requires API SE-rated SAE 10W-40 mineral oil (Fiat SIB 79-ME-018). 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/6789). 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. B14033).
Fiat Technical Information System (TIS): Docs B13680, B14033, SIB 79-ME-018
VCA Type Approval Database (VCA/EMS/6789)
ISO 1585:1996 Road vehicles — Engine test code — Net power
The Fiat 131 FZ was used across Fiat's 131 platform with longitudinal mounting and no licensed external usage. This engine received platform-specific adaptations-upgraded cooling in the Supermirafiori and emissions-tuned carburettors in UK-market sedans-and from 1979 the facelifted Mirafiori series adopted revised cylinder head 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 B13900). The 8th digit of the VIN indicates engine type ('F' for 2.0L FZ series). Pre-1979 models have chrome valve covers with ribbed air cleaners; post-1979 units use black-painted covers. Critical differentiation from 1.6L variants: The 131 FZ uses a Weber 36 DCF twin-choke carburettor, while 1.6L models use a 32 DATR. Service parts require model-year verification—head gaskets and valve springs differ between pre- and post-1979 builds per Fiat SIB 79-ME-018.
The 131 FZ's primary reliability risk is carburettor icing and mixture imbalance in cold climates, with elevated incidence in high-humidity environments. Internal Fiat field reports from 1980 indicated over 18% 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-FZ.
Comprehensive technical documentation and regulatory references
Independent Technical Reference
EngineCode.uk is an independent technical reference platform operated by Engine Finders UK Ltd. We are not affiliated with FIAT or any other manufacturer. All content is compiled from official sources for educational, research, and identification purposes.
Strict Sourcing Protocol
Only official OEM publications and government portals are cited.
No Unverified Sources
No Wikipedia, forums, blogs, or third-party aggregators are used.
Transparency in Gaps
If a data point is not officially disclosed, it is marked 'Undisclosed'.
Regulatory Stability
EU regulations are referenced using CELEX identifiers for long-term stability.
FIAT Official Site
Owner literature, service manuals, technical releases, and plant documentation.
EUR-Lex
EU emissions and type-approval regulations (e.g., CELEX:32007R0715, CELEX:32017R1151).
GOV.UK: Vehicle Approval & V5C
UK vehicle approval processes, import rules, and MoT guidance.
DVLA: Engine Changes & MoT
Official guidance on engine swaps and inspection implications.
Vehicle Certification Agency (VCA)
UK type-approval authority for automotive products.
Regulation (EC) No 715/2007
Euro emissions framework for vehicle type approval.
Commission Regulation (EU) 2017/1151
WLTP and RDE testing procedures for emissions certification.
GOV.UK: Vehicle Approval
UK compliance and certification requirements for imported and modified vehicles.
VCA Certification Portal
Type-approval guidance and documentation.
Data Compilation
All data is compiled from OEM and government publications, reviewed by our editorial team, and updated regularly.
Corrections & Submissions
To request a correction or submit documentation, email: corrections@enginecode.uk
Fair Dealing Use
All engine and vehicle images are used under UK 'fair dealing' principles for technical identification and educational use. Rights remain with their respective owners.
Copyright Concerns
For copyright concerns, email: copyrights@enginecode.uk
GDPR Compliance
EngineCode.uk complies with UK GDPR. We do not collect personal data unless explicitly provided.
Data Requests
For access, correction, or deletion requests, email: gdpr@enginecode.uk
Trademark Notice
All trademarks, logos, and engine codes are the property of their respective owners. Use on this site is strictly for reference and identification.
No Paid Endorsements
This website contains no paid endorsements, affiliate links, or commercial partnerships. We do not sell parts or services.
Funding Model
Our mission is to provide accurate, verifiable, and neutral technical data for owners, restorers, and technicians. This site is self-funded.
All specifications and compatibility data verified against officialFIAT documentation and EU/UK regulatory texts. Where official data is unavailable, entries are marked “Undisclosed“ .
All external links open in new tabs. Please verify current availability of resources.
