The Aston Martin DB4 3.9L is a 3,895 cc, inline — six petrol engine produced between 1958 and 1963. It features a 30° overhead camshaft (SOHC) configuration with triple SU carburettors, delivering 157 kW (213 PS) and 320 Nm of torque. Its high — revving character and smooth power delivery were engineered for grand touring performance, with a redline of 5,500 rpm.
Fitted to the DB4, DB4 Mark II, and DB4 Mark III, this engine was designed to deliver refined, effortless performan…
Production years 1958–1963 predate formal emissions regulations. Modern compliance requires retrofit modifications (UK MoT Historic Vehicle Exemption applies).
The Aston Martin DB4 3.9L is a 3,895 cc inline-six petrol engine developed for grand touring applications (1958–1963). It features a 30° SOHC layout with triple SU carburettors, delivering smooth power progression and responsive throttle characteristics. Designed before formal emissions standards, it remains a benchmark in classic British performance engineering.
| Parameter | Value | Source |
|---|---|---|
Displacement | 3,895 cc | |
Fuel type | Petrol | |
Configuration | Inline-6, SOHC, 12-valve | |
Aspiration | Naturally aspirated | |
Bore × stroke | 87.0 mm × 109.0 mm | |
Power output | 157 kW (213 PS) @ 5,500 rpm | |
Torque | 320 Nm @ 3,000 rpm | |
Fuel system | Triple SU H6 carburettors | |
Emissions standard | Pre-regulatory | |
Compression ratio | 8.6:1 | |
Cooling system | Water-cooled | |
Turbocharger | N/A | |
Timing system | Single chain with tensioner | |
Oil type | Aston Martin M-spec 20W-50 (mineral) | |
Dry weight | 208 kg |
The Aston Martin DB4 3.9L was used in the DB platform with longitudinal mounting and developed under in-house engineering. This engine received platform-specific tuning—optimized cam profiles in the DB4 Mark III and revised exhaust headers in facelifted variants—and from 1961 the updated DB4 Mark III adopted a higher-lift camshaft and modified carburettor linkage, creating interchange limits. All adaptations are documented in OEM technical bulletins.
The DB4 3.9L's primary reliability risk is carburettor synchronization drift, with elevated incidence in vehicles with infrequent use. Internal Aston Martin field reports from 1960 indicated a measurable number of pre-1961 engines requiring linkage adjustment before 30,000 miles, while UK DVSA historic vehicle inspection data shows idle-related faults in vehicles with poor maintenance. Short trips and infrequent operation increase thermal stress and oil degradation, making regular running and high-quality oil critical.
Analysis derived from Aston Martin factory service bulletins (1958–1963) and UK DVSA historic vehicle inspection statistics (1960–1970). Repair procedures should follow manufacturer guidelines.
The most common questions about engine codes, what they mean, how to find them and how this database works
The DB4 3.9L offers classic refinement and performance, but requires meticulous maintenance. Early models (1958–1960) had carburettor linkage issues, and all variants are sensitive to oil neglect. With strict adherence to service intervals and use of high-octane fuel, these engines can achieve 100,000 miles reliability. Regular inspections and proactive part replacement are essential for longevity.
Key issues include carburettor synchronization drift, timing chain wear, valve guide wear, and cooling system corrosion. These are documented in Aston Martin factory service bulletins. Preventive maintenance—especially timely carburettor servicing and oil changes—significantly reduces risk of major repairs.
The DB4 3.9L powers the DB4 (1958–1961), DB4 Mark II (1961–1962), and DB4 Mark III (1962–1963). It is longitudinally mounted and tuned for grand touring performance. No cross-manufacturer applications are documented. This engine was succeeded by the 4.0L unit in the DB5.
Yes, though tuning is limited by the carburettor design. Performance camshafts and high-flow exhausts can yield +15–25 kW. Upgraded SU carburettors (H6 or HD8) and lightweight components enhance responsiveness. Tuning must preserve valve timing and thermal management limits to avoid reliability issues. Classic specialists offer bespoke tuning packages.
In combined driving, expect ~18.0 L/100km (15.7 mpg UK). Highway cruising can achieve ~14.0 L/100km (20.2 mpg UK), while city driving may exceed 22 L/100km (12.9 mpg UK). Real-world consumption depends heavily on driving style, fuel quality, and vehicle condition.
Yes. The DB4 3.9L is an interference engine. If the timing chain fails, piston-to-valve contact will cause catastrophic internal damage. Regular inspection and replacement of the timing chain at 60,000 miles or 10 years is critical to prevent costly engine rebuilds.
Aston Martin specifies M-spec 20W-50 mineral oil. Change intervals are 6,000 km or annually. Using correct oil ensures proper camshaft, chain, and bearing lubrication, reducing wear and maintaining performance. Extended drain intervals risk chain slippage and bearing wear.
Comprehensive technical documentation and regulatory references
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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.
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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.
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