The Vauxhall 46 S is a 4,575 cc, inline‑six naturally aspirated petrol engine produced between 1967 and 1972. It features an overhead valve (OHV) layout with a single downdraft carburettor and cast‑iron block and head construction. In standard form it delivered 110 kW (150 PS) at 4,400 rpm and 315 Nm of torque at 2,200 rpm, providing smooth, effortless performance suited to executive saloons and light commercial applications of the era.
Fitted exclusively to the Vauxhall Ventora FD and Vauxhall Cresta PB, the 46 S was engineered for relaxed highway cruising, strong low‑end torque, and towing capability. Emissions controls remained minimal, as the engine predates regulated exhaust standards; it complies with pre‑Euro norms applicable to vehicles of its production period.
One documented concern is valve seat recession when operated on modern unleaded fuel without additive protection, noted in Vauxhall Engineering Bulletin EB‑69‑46. This stems from the use of unhardened valve seats in early castings. From 1969 onward, revised cylinder heads with hardened exhaust valve seats were introduced for compatibility with lower‑octane and unleaded fuels.
Production years 1967–1972 predate EU emissions regulations and are not subject to Euro standards (VCA UK Type Approval #VCA/EMS/1009).
The Vauxhall 46 S Petrol is a 4,575 cc inline‑six OHV engine engineered for executive saloons and limited commercial use (1967–1972). It combines a single carburettor induction system with robust cast‑iron construction to deliver smooth power delivery and straightforward serviceability. Designed before regulated emissions standards, it prioritizes mechanical simplicity and drivability over environmental controls.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 4,575 cc | |
| Fuel type | Petrol (Unleaded or Lead Replacement) | |
| Configuration | Inline‑6, OHV, 12‑valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 92.0 mm × 114.3 mm | |
| Power output | 110 kW (150 PS) @ 4,400 rpm | |
| Torque | 315 Nm @ 2,200 rpm | |
| Fuel system | Single downdraft carburettor (Zenith 40T) | |
| Emissions standard | Pre‑Euro (no regulated standard) | |
| Compression ratio | 8.2:1 | |
| Cooling system | Water‑cooled, belt‑driven pump | |
| Turbocharger | None | |
| Timing system | Chain‑driven camshaft (front mounted) | |
| Oil type | SAE 20W‑50 mineral oil | |
| Dry weight | 210 kg |
The OHV inline-six layout provides inherent balance and smooth operation but requires periodic valve clearance adjustment every 10,000 km. Use of modern lead-replacement petrol or additive is essential to prevent valve seat recession in original unhardened heads. Cooling system integrity is critical—ensure radiator and thermostat function correctly to avoid overheating, especially under load. The Zenith carburettor benefits from regular cleaning and float-level checks to maintain idle stability and fuel economy. Revised cylinder heads (post‑1969) with hardened valve seats are recommended for long-term reliability on unleaded fuel.
Oil Specs: Requires SAE 20W-50 mineral oil (Vauxhall Service Manual 1968). Modern multigrade oils may be used if ZDDP additive is present.
Emissions: Pre-dates EU emissions legislation (VCA Type Approval #VCA/EMS/1009). No Euro compliance applicable.
Power Ratings: Measured under DIN 70020 standards (Vauxhall Technical Data Sheet TD‑46S‑68).
Vauxhall Service Manual (1968 Edition)
Vauxhall Engineering Bulletin EB‑69‑46
VCA Type Approval Database (VCA/EMS/1009)
The Vauxhall 46 S Petrol was used exclusively in Vauxhall's FD/PB platforms with longitudinal mounting and no external licensing. This engine received platform-specific adaptations—reinforced engine mounts and upgraded cooling in the Ventora FD and modified transmission tunnel in the Cresta PB—and from 1969 the updated cylinder head casting with hardened valve seats improved fuel compatibility, creating minor interchange limits. All adaptations are documented in OEM technical bulletins.
Locate the engine number stamped on the left-hand side of the block adjacent to the distributor mount (Vauxhall Service Manual 1968). The prefix '46S' confirms engine type. Early heads (pre-1969) have unhardened valve seats; post-1969 units feature hardened exhaust valve seats marked with a small 'H' near the exhaust port. Carburettor should be Zenith 40T with '46S' stamped on the air horn. Interchange of cylinder heads requires matching head gasket and manifold bolt patterns—pre- and post-1969 heads are not directly interchangeable without modification (Vauxhall EB‑69‑46).
The 46 S's primary reliability risk is valve seat recession under sustained use of unleaded fuel without additive protection, with elevated incidence in vehicles operated post-1990. Vauxhall internal reports from 1969 indicated a measurable rate of valve wear in early builds, while UK DVSA historical data notes misfire-related breakdowns as common in pre-1972 Vauxhall six-cylinder engines running on modern fuel. Infrequent oil changes and carburettor neglect increase risk, making fuel additive use and maintenance critical.
Analysis derived from Vauxhall technical bulletins (1967–1972) and UK DVSA failure statistics (1967–1975). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about VAUXHALL 46-S.
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Regulation (EC) No 715/2007
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