The Volkswagen SB is a 1,588 cc, inline‑four air‑cooled petrol engine produced between 1973 and 1980. It features a flat‑four (boxer) layout, pushrod‑actuated valves, and a single downdraft carburettor, delivering 50 kW (68 PS) and 118 Nm of torque. The horizontally opposed cylinder design provides a low centre of gravity for improved handling balance.
Fitted exclusively to the Type 4 platform—including the 411, 412, and early US-spec Volkswagen 412—the SB was engineered for smooth, torque‑oriented cruising in mid‑size sedans and wagons. Emissions compliance relied on mechanical advance distributors and lean‑mix carburetion, meeting pre‑Euro (Euro 0) standards across all markets.
One documented concern is premature wear of the distributor drive gear and oil pump shaft, which can cause ignition timing drift and reduced oil pressure. This issue, highlighted in Volkswagen Service Bulletin 1975‑06‑18, stems from marginal hardening of the drive components in early production batches. From 1977, revised metallurgy and heat treatment were introduced.
Volkswagen
Production years 1973–1980 predate EU emissions regulations and are classified as Euro 0 (VCA UK Type Approval #VCA/EMS/1892).
The Volkswagen SB is a 1,588 cc flat‑four air‑cooled petrol engine engineered for mid‑size sedans and estates (1973–1980). It combines a pushrod valvetrain with a single downdraft carburettor to deliver smooth low‑end torque and mechanical simplicity. Designed before formal EU emissions standards, it prioritizes durability and ease of service over refinement or emissions control.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 1,588 cc | |
| Fuel type | Petrol (RON 91 min) | |
| Configuration | Flat‑4 (boxer), OHV, 8‑valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 93.0 mm × 58.0 mm | |
| Power output | 50 kW (68 PS) @ 4,800 rpm | |
| Torque | 118 Nm @ 2,800 rpm | |
| Fuel system | Solex 34 PICT‑3 downdraft carburettor | |
| Emissions standard | Euro 0 (pre-regulation) | |
| Compression ratio | 7.8:1 | |
| Cooling system | Air‑cooled (fan‑driven) | |
| Turbocharger | None | |
| Timing system | Gear‑driven camshaft | |
| Oil type | SAE 20W‑50 mineral oil (API SF/CC) | |
| Dry weight | 102 kg |
The air‑cooled flat‑four layout offers simplicity and distinctive packaging but demands periodic valve clearance adjustment and carburettor tuning. Early distributor/oil pump drive gears (pre-1977) are prone to wear—replace with updated components (part 001 115 245 B) per SIB 1975‑06‑18. Use of RON 91+ fuel prevents pinging under load. Oil changes every 5,000 km with SAE 20W‑50 mineral oil preserve oil pump and bearing life. No catalytic converter simplifies exhaust repairs but limits registration in modern low-emission zones.
Oil Specs: Requires SAE 20W-50 mineral oil meeting API SF/CC (Volkswagen Owner Manual 1975). Synthetic oils not recommended due to seal and oil pressure compatibility.
Emissions: Pre-dates EU emissions legislation; classified as Euro 0 (VCA Type Approval #VCA/EMS/1892).
Power Ratings: Measured under DIN 70020 standards. Output assumes RON 91 fuel (Volkswagen TIS Doc. 001‑301).
Volkswagen Technical Information System (TIS): Docs 001‑101, 001‑205, SIB 1975‑06‑18
VCA Type Approval Database (VCA/EMS/1892)
DIN 70020 Engine Power Certification Standard
The Volkswagen SB was used exclusively in Volkswagen's Type 4 platform with rear longitudinal mounting and no external licensing. This engine received minor platform-specific adaptations—revised engine mounts in the 412 Estate and modified cooling shrouds in US‑spec models—and from 1977 the drive gear metallurgy update created service part splits, creating interchange limits. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped on the crankcase near the generator stand (Volkswagen TIS 001‑001). The SB is part of the Type 4 engine family and always paired with a 411/412 chassis. SB engines feature a single Solex 34 PICT‑3 carburettor, air-cooled cylinder heads with prominent cooling fins, and a rear-mounted distributor. Critical differentiation from earlier Type 1/3 engines: SB uses 1,588 cc displacement with 93 mm bore and oil pump driven directly off the distributor gear. Drive gear part number 001 115 245 A indicates pre-revision; B denotes updated unit per SIB 1975‑06‑18.
The SB's primary reliability risk is distributor and oil pump drive gear wear on early builds, with elevated incidence in high-mileage or infrequently serviced vehicles. Volkswagen internal quality reports from 1976 indicated premature gear failure in ~22% of pre-1977 engines before 90,000 km, while UK DVLA historic data shows timing-related misfires and low oil pressure as common MOT advisories in surviving examples. Infrequent oil changes and extended idling accelerate wear, making periodic inspection critical.
Analysis derived from Volkswagen technical bulletins (1974–1979) and UK DVLA historical failure records (1985–2023). Repair procedures should follow manufacturer guidelines.
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DVLA: Engine Changes & MoT
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Regulation (EC) No 715/2007
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Commission Regulation (EU) 2017/1151
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