The Volvo B 20 F is a 1,986 cc, inline‑four petrol engine produced between 1969 and 1974. It features a cast‑iron block, overhead valves (OHV) actuated by pushrods, and a twin‑choke downdraft carburettor. In standard tune for the 140 series, it delivered approximately 74 kW (100 PS), providing a noticeable power increase over the B18 for larger Volvo sedans and wagons.
Fitted primarily to the Volvo 140 series (142, 144, 145) and early 240 series prototypes, the B 20 F was engineered for smooth, torquey performance in heavier vehicles. Emissions compliance for North American models was addressed through early evaporative controls and modified carburetion, generally meeting the US Federal standards applicable for its production period.
One documented service consideration is the potential for distributor drive gear wear, particularly when paired with high-mileage mechanical fuel pumps. This issue, noted in Volvo Service Bulletin 71‑03 (which also covered the B18), can lead to ignition timing drift. The engine received minor updates throughout its run before being succeeded by the B21 with overhead camshaft design.
Production years 1969–1974 predate formal Euro emissions standards. US models complied with applicable US Federal Motor Vehicle Safety Standards (FMVSS) for the model year (NHTSA Historical Data).
The Volvo B 20 F is a 1,986 cc inline‑four petrol engine engineered for mid-size to large sedans and wagons (1969-1974). It combines a robust cast‑iron block with a simple OHV valvetrain and twin-choke carburetion to deliver smooth, tractable power. Designed to meet contemporary national emissions regulations, it prioritizes mechanical simplicity and ease of service.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 1,986 cc | |
| Fuel type | Petrol | |
| Configuration | Inline‑4, OHV, 8‑valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 88.9 mm × 80.0 mm | |
| Power output | 74 kW (100 PS) @ 5,500 rpm | |
| Torque | 155 Nm @ 3,500 rpm | |
| Fuel system | Twin-choke downdraft carburettor (e.g., Zenith 36 NDIX) | |
| Emissions standard | US Federal (Pre-Catalyst) | |
| Compression ratio | 9.0:1 | |
| Cooling system | Water‑cooled | |
| Turbocharger | None | |
| Timing system | Chain‑driven camshaft | |
| Oil type | SAE 20W‑50 (Mineral) | |
| Dry weight | Not specified in available OEM docs |
The OHV design offers simplicity and ease of repair but delivers modest power by modern standards. Regular oil changes (every 5,000-8,000 km) with quality mineral oil are critical. The twin-choke carburettor requires periodic synchronization and cleaning for optimal running. Distributor drive gear wear, documented in Service Bulletin 71-03, can cause timing issues; inspect during major services. Genuine or high-quality reproduction parts are recommended for rebuilds.
Oil Specs: Original specification was SAE 20W-50 mineral oil (Volvo Workshop Manual 1972). Modern high-detergent equivalents are often used.
Emissions: Formal Euro standards did not exist. US models complied with contemporary US Federal standards (NHTSA FMVSS).
Power Ratings: Measured under SAE gross horsepower standards common for the era (Volvo Technical Specification Sheet B20F).
Volvo Workshop Manual (1972 Edition)
Volvo EPC Archive Documentation (VEP-B20-001)
Volvo Service Bulletin 71-03
NHTSA FMVSS Historical Compliance Records
The Volvo B 20 F was used across Volvo's 140 Series platforms with longitudinal mounting. This engine received minor carburettor and emission control revisions over its lifespan, but no major facelifts created significant interchange limits. All adaptations are documented in OEM technical bulletins.
The engine code "B20F" is typically stamped on a flat pad on the left-hand side of the engine block, near the distributor. The casting number for the block is often 1225400. Visually, it is identified by its cast-iron construction, side-mounted distributor, and twin-choke downdraft carburettor. Differentiation from the B18 is by its larger displacement and specific casting numbers; it is distinct from the later B21 by its OHV valvetrain versus OHC.
The B 20 F's primary long-term concern is distributor drive gear wear, particularly in high-mileage examples or those with original mechanical fuel pumps. Volvo Service Bulletin 71-03 documented this as a cause of ignition timing drift. Consistent operation and adherence to maintenance schedules are critical for preventing drivability issues.
Analysis derived from Volvo service bulletins (1970-1975) and workshop manuals (1972). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about VOLVO B-20-F.
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