The Fiat 149 B3.000 – Petrol is a 2,997 cc, inline-six, naturally aspirated engine produced between 1983 and 1988. It was engineered as a smooth, high-torque powerplant for Fiat's executive and luxury vehicle segment. Featuring a cast-iron block, aluminium head, and twin-choke carburettor (Weber 38 DCOE), it delivers 110 kW (150 PS) at 5,000 rpm and 245 Nm of torque at 2,800 rpm. Its OHV (overhead valve) pushrod design ensures mechanical simplicity and ease of maintenance.
Fitted to flagship models such as the Fiat 132 3.0, Fiat Regata 3.0, and Lancia Gamma, the 149 B3.000 – Petrol was designed for refined cruising and strong mid-range performance. It offered a balance of linear power delivery and durability, suitable for long-distance driving. Emissions compliance was achieved through an air injection system and catalytic converter on post-1985 models, meeting early Euro 1 precursor standards in select European markets.
One documented concern is main bearing wear under sustained high-speed operation, highlighted in Fiat Service Information Bulletin 84-10-05. This issue stems from marginal oil flow design in the crankshaft main journals, particularly in vehicles subjected to extended highway driving. Later production revisions included improved oil gallery machining and revised bearing metallurgy to enhance lubrication and load tolerance.
Production years 1983–1985 meet pre-Euro emissions standards; 1986–1988 models comply with early Euro 1 equivalent regulations depending on market (EU Directive 83/351/EEC, Annex II).
The Fiat 149 B3.000 – Petrol is a 2,997 cc inline-six naturally aspirated engine developed for Fiat's executive and luxury vehicles (1983–1988). It combines a durable cast-iron block with an aluminium cylinder head and twin-choke carburettor to deliver smooth, high-torque performance. Designed for long-distance comfort and reliability, it meets early European emissions requirements while maintaining mechanical robustness.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 2,997 cc | |
| Fuel type | Petrol (Unleaded RON 95) | |
| Configuration | Inline-6, OHV, 12-valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 88.0 mm × 82.0 mm | |
| Power output | 110 kW (150 PS) @ 5,000 rpm | |
| Torque | 245 Nm @ 2,800 rpm | |
| Fuel system | Weber 38 DCOE twin-choke carburettor | |
| Emissions standard | Pre-Euro (1983–1985); Euro 1 equivalent (1986–1988) | |
| Compression ratio | 9.2:1 | |
| Cooling system | Water-cooled, thermostat-regulated | |
| Turbocharger | Not applicable | |
| Timing system | Chain-driven camshaft (single-row) | |
| Oil type | SAE 10W-40 (API SF/CC) | |
| Dry weight | 178 kg |
The naturally aspirated inline-six design provides smooth, linear power delivery ideal for relaxed cruising but requires regular carburettor tuning to maintain efficiency. SAE 10W-40 mineral oil is recommended with changes every 10,000 km to protect the chain-driven OHV system. The engine is sensitive to prolonged high-speed operation due to oil flow limitations in the main bearings; periodic inspection of bearing clearance and oil pressure is advised. Use of unleaded fuel requires hardened valve seats, retrofitted in later models per Fiat SIB 85-12-08. Pre-1986 units lack catalytic converters; post-1985 models require lead-free fuel and periodic catalyst inspection to prevent blockage.
Oil Specs: Requires SAE 10W-40 API SF/CC specification (Fiat Owner's Manual 149-OM3). Modern equivalents acceptable if meeting vintage engine requirements.
Emissions: Euro 1 equivalent applies to 1986–1988 models only (EU Directive 83/351/EEC). Pre-1986 units meet national pre-regulatory standards.
Power Ratings: Measured under UN ECE Regulation 85. Output assumes clean air filter, correct ignition timing, and fresh fuel system (Fiat TIS M149P03).
Fiat Technical Information System (TIS): Docs M149P03, SIB 84-10-05
European Commission: Directive 83/351/EEC - Emissions for Light-Duty Vehicles
UN ECE Regulation 85: Power Measurement for Compression Ignition Engines
Fiat ETK Parts Catalogue Vol. 3: Engine Components
The Fiat 149 B3.000 – Petrol was used across Fiat's 132/Regata platforms with longitudinal mounting and shared with Lancia in luxury applications. This engine received platform-specific adaptations—tuned exhaust manifolds in the 132 and reinforced engine mounts in the Regata—and from 1986, the introduction of catalytic converters on export models created emissions-related interchange limits. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped horizontally on the front-facing side of the cylinder block, near the starter motor mount (Fiat TIS M149P03). The 8th VIN digit indicates engine type ('H' for 149 B-series petrol). Pre-1986 models have chrome valve covers with air cleaners; post-1986 units feature black-painted covers with emissions vacuum lines. Critical differentiation from diesel variants: 149 B3.000 petrol has a carburettor and distributor, while diesel versions use injection pumps. Service parts require model-year verification—cylinder heads for pre-1986 models lack hardened valve seats and are incompatible with unleaded fuel systems (Fiat SIB 85-12-08).
The 149 B3.000 – Petrol's primary reliability risk is main bearing wear, with elevated incidence in vehicles used for sustained highway driving. Internal Fiat quality reports from 1986 noted a significant number of pre-1986 engines requiring bearing replacement before 120,000 km, while Italian Ministry of Transport data links a notable share of engine failures to oil system neglect. Extended high-speed operation and poor oil maintenance increase stress on the main journals, making oil quality and pressure checks critical.
Analysis derived from Fiat technical bulletins (1983-1988) and Italian Ministry of Transport vehicle failure statistics (1984-1989). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about FIAT 149-B3-000.
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