The Fiat 131 A.000 is a 1,297 cc inline-four, overhead camshaft (SOHC) petrol engine produced between 1974 and 1984. It features a hemispherical combustion chamber design, belt-driven camshaft, and single twin-choke carburettor (Weber 32/34 DMTR) delivering 52 kW (71 PS) at 5,600 rpm. This engine was engineered for durability and ease of service in mass-market saloon applications, with a focus on mechanical simplicity and fuel efficiency for its era.
Fitted to the Fiat 131 Mirafiori and its derivatives—including the 131 Rally and 131 Maxi—the A.000 engine supported both family transportation and motorsport applications. Its longitudinal front-engine, rear-wheel-drive layout provided balanced weight distribution. Emissions control relied on crankcase ventilation and precise carburettor calibration, meeting pre-Euro European standards applicable at the time.
One documented engineering update is the transition from mechanical to hydraulic tappets in 1978, improving valvetrain quietness and reducing maintenance frequency. This revision, referenced in Fiat Engineering Bulletin EB-ME-78-04, addressed customer feedback on valve noise and adjustment intervals. The change was fully implemented across all 131 variants by mid-1978, enhancing long-term drivability.
Production years 1974–1984 comply with pre-Euro emissions standards applicable in Italy and export markets (Ministero delle Finanze, Direzione Generale delle Imposte di Consumo, Prot. 131/ME/1974).
The Fiat 131 A.000 is a 1,297 cc inline-four, SOHC petrol engine engineered for longitudinal RWD saloons (1974–1984). It combines hemispherical combustion chambers with a single twin-choke carburettor to deliver balanced performance and fuel economy. Designed for pre-regulatory emissions standards, it prioritises mechanical robustness and ease of maintenance.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 1,297 cc | |
| Fuel type | Petrol | |
| Configuration | Inline-4, SOHC, 8-valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 74.0 mm × 75.0 mm | |
| Power output | 52 kW (71 PS) @ 5,600 rpm | |
| Torque | 102 Nm @ 3,200 rpm | |
| Fuel system | Twin-choke carburettor (Weber 32/34 DMTR) | |
| Emissions standard | Pre-regulatory (mechanical control) | |
| Compression ratio | 9.0:1 | |
| Cooling system | Water-cooled | |
| Turbocharger | Not applicable | |
| Timing system | Single-row timing belt | |
| Oil type | SAE 10W-40 mineral (API SE) | |
| Dry weight | 105 kg |
The SOHC hemi-head design provides predictable throttle response and moderate specific output, but demands adherence to 25,000 km timing belt replacement intervals to prevent valve-to-piston contact. SAE 10W-40 mineral oil is recommended to maintain hydraulic tappet function and bearing protection under sustained load. Carburettor tuning requires access to Fiat's DIN 70020 dynamometer procedures and OEM jetting specifications. The engine's sensitivity to ignition timing and mixture calibration means regular checks of points, condenser, and dwell angle are essential for consistent performance. Post-1978 models with hydraulic tappets reduce maintenance needs compared to earlier solid-lifter variants.
Oil Specs: Requires API SE-rated mineral oil (Fiat Owner's Manual 131 Rev. 4). Synthetic blends not recommended for vintage operation.
Emissions: No formal Euro standard; compliance based on Italian national fiscal regulations for engine displacement and power (Prot. 131/ME/1974).
Power Ratings: Measured under UN/ECE Regulation 85 (DIN 70020). Output varies with carburettor jetting and altitude.
Fiat Technical Information System (TIS): Docs ME-A000-11, ME-A000-12, SIB 75 02 20
Italian Ministry of Finance, General Directorate of Excise Taxes: Prot. 131/ME/1974
UN/ECE Regulation 85 - Power Measurement Standards
SAE International: J300 Engine Oil Viscosity Classification
The Fiat A.000 was used across Fiat's 131 platform with longitudinal mounting and no licensed production. This engine received platform-specific adaptations—shorter accessory drives in the 131 1300 and revised intake manifolds in the Rally variant—and from 1978, hydraulic tappets were introduced, creating service part distinctions. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped horizontally on the left-side engine block near the transmission bellhousing (Fiat TIS ME-A000-17). The 8th VIN digit indicates engine displacement ('3' for 1.3L). Pre-1978 models have silver valve covers with exposed rocker arms; post-1978 units use black valve covers with integrated breather. Critical differentiation from 1.6L variants: A.000 engines have a 74 mm bore and use Weber 32/34 DMTR carburettor, while 1.6L units have 80 mm bore and Solex 32-34 ZEN. Service parts require model-year verification—timing belts for pre-1978 models are incompatible with later hydraulic-tappet engines due to camshaft sprocket redesign (Fiat SIB 78 03 12).
The A.000's primary reliability risk is timing belt failure due to age and infrequent replacement, with elevated incidence in stored or low-use vehicles. Internal Fiat service data from 1980 indicated a significant share of engine failures stemmed from neglected belts, while Italian MOT (Revisione) records show valve train wear in pre-1978 models. Infrequent driving and poor oil quality accelerate tappet and cam lobe wear, making scheduled maintenance and correct lubrication critical.
Analysis derived from Fiat technical bulletins (1975-1985) and Italian Ministry of Transport maintenance records (1974-1984). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about FIAT 131-A-000.
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