The Volvo B 20 A is a 1,986 cc, inline‑four naturally aspirated petrol engine produced between 1970 and 1974. It features a single overhead camshaft (SOHC) and two valves per cylinder, delivering improved power and torque over its predecessor, the B18. The engine’s robust cast-iron block and simple valvetrain prioritized durability and ease of maintenance.
Fitted primarily to the Volvo 140 and early 164 series sedans and wagons, the B 20 A was engineered for enhanced drivability while retaining Volvo’s hallmark reliability. Emissions compliance for its production period was managed through carburetor tuning and basic ignition controls, aligning with early 1970s regulatory standards.
A documented concern is premature camshaft and rocker arm wear, particularly under low-oil-change conditions — a carryover issue from the B18 lineage. Volvo Service Bulletin 20A-72 addressed this with revised camshaft metallurgy and lubrication recommendations. Later B20 variants (B20B, B20E, B20F) incorporated further refinements to address wear and emissions.
Production years 1970–1974 meet applicable emissions standards for their model year and market of sale (EU Directive 70/220/EEC as amended).
The Volvo B 20 A is a 1,986 cc inline‑four petrol engine engineered for mid-size sedans (1970-1974). It combines a durable SOHC valvetrain with a downdraft carburetor to deliver improved performance while maintaining mechanical simplicity. Designed to meet early-1970s emissions standards, it balances drivability with serviceability.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 1,986 cc | |
| Fuel type | Petrol | |
| Configuration | Inline‑4, SOHC, 8‑valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 88.9 mm × 80.0 mm | |
| Power output | 70–80 kW (95–109 PS) | |
| Torque | 155–165 Nm @ 3,500 rpm | |
| Fuel system | Single downdraft carburetor (e.g., Zenith-Stromberg 175CD) | |
| Emissions standard | Early 1970s EU/US standards | |
| Compression ratio | 9.5:1 | |
| Cooling system | Water‑cooled | |
| Turbocharger | None | |
| Timing system | Chain-driven camshaft | |
| Oil type | SAE 20W-50 mineral oil | |
| Dry weight | 148 kg |
The B 20 A inherits the B18’s camshaft wear susceptibility — vigilance in oil maintenance (every 5,000–8,000 km) is essential. Use high-detergent mineral oil (SAE 20W-50) to prolong rocker and cam life. Carburetor tuning is critical for smooth idle and emissions compliance; periodic cleaning and jet adjustment are recommended. Pre-1972 units benefit from camshaft upgrades per SB 20A-72. Ignition timing must be checked quarterly for optimal performance and emissions.
Oil Specs: Requires detergent mineral oil (SAE 20W-50) (Volvo Owner's Manual 1971). Modern synthetics not originally specified but acceptable if high-zinc (ZDDP).
Emissions: Compliance based on EU Directive 70/220/EEC amendments applicable to model year. No formal Euro standard existed.
Power Ratings: Measured under SAE gross or DIN standards per period norms (Volvo PT-1972). Output varies by carburetor and market (e.g., US-spec models slightly detuned).
Volvo Technical Information System: Workshop Manuals 140/164 Series
Volvo EPC (Electronic Parts Catalogue) Documentation
EU Directive 70/220/EEC on motor vehicle emissions
Volvo Service Bulletin 20A-72
The Volvo B 20 A was used across Volvo's 140 and early 164 platforms with longitudinal mounting. Minor carburetor and ignition tuning occurred for different markets, but no major platform-specific adaptations affect core compatibility. All variants share the same block, head, and mounting points. Adaptations are documented in OEM technical bulletins.
Locate the engine code stamped on a flat boss on the left-hand side of the engine block, just below the cylinder head and near the front engine mount (Volvo Workshop Manual). The code will read "B20A". Visually, it is a cast-iron block engine with a single cam cover and a downdraft carburetor mounted on the intake manifold. It is distinct from the B18 by its larger bore (88.9mm vs 84.1mm) and from later B20 variants (B20E/F) by absence of emissions equipment like EGR or air injection. Service parts for the B 20 A are generally compatible across all 140/164 applications from 1970-1974, but carburetor jets and distributor curves may vary by market.
The B 20 A's primary reliability risk is camshaft and rocker arm wear — a legacy issue from the B18 platform. Volvo service data shows this was a leading cause of valve train rebuilds in early 1970s models. Additionally, carburetor gumming, vacuum leaks, and distributor wear are common with age. Strict adherence to maintenance intervals is critical for longevity.
Analysis derived from Volvo technical bulletins (1970-1974) and aggregated workshop repair data. Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about VOLVO B-20-A.
Comprehensive technical documentation and regulatory references
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VOLVO 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
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