The Ford EYDJ – Petrol is a 4,942 cc, overhead — valve (OHV), inline — six engine produced by Ford of Britain between 1967 and 1972. It was developed as a high — torque variant of the Ford Zephyr inline — six family, featuring a single carburettor and pushrod valvetrain. This engine delivered 150 bhp at 4,300 rpm and 260 lb — ft of torque at 2,400 rpm, making it ideal for full — size saloons and commercial chassis requiring strong pulling power.
Fitted to the Ford Zephyr Mark IV (Serie…
Production years 1967–1972 predate mandatory European emissions standards; no Euro classification applies , Pre-1970 Series).
The Ford EYDJ – Petrol is a 4,942 cc inline-six OHV engine engineered for full-size saloons and commercial vehicles (1967–1972). It combines a robust pushrod valvetrain with a single SU carburettor to deliver strong low-RPM torque and smooth cruising performance. Designed in a pre-emissions-regulation era, it prioritises mechanical reliability and serviceability over environmental compliance.
| Parameter | Value | Source |
|---|---|---|
Displacement | 4,942 cc | |
Fuel type | Petrol (Unleaded RON 95 compatible with additives) | |
Configuration | Inline-6, OHV, 12-valve | |
Aspiration | Naturally aspirated | |
Bore × stroke | 95.0 mm × 116.0 mm | |
Power output | 150 hp (112 kW) @ 4,300 rpm | |
Torque | 260 lb-ft (352 Nm) @ 2,400 rpm | |
Fuel system | Single SU HD8 carburettor | |
Emissions standard | Pre-regulatory (no Euro classification) | |
Compression ratio | 8.7:1 | |
Cooling system | Water-cooled, pressurised radiator | |
Turbocharger | Not applicable | |
Timing system | Chain-driven camshaft | |
Oil type | SAE 20W-50 mineral oil | |
Dry weight | 225 kg |
The Ford EYDJ – Petrol was used across Ford's Mark IV Series 3 platform with longitudinal mounting and applied to both passenger and commercial derivatives. This engine received platform-specific adaptations-fuel pump revisions in the Thames 400E and dual-exhaust options in performance-oriented Zodiac trims-and from 1969 minor carburettor and ignition tuning changes were introduced, creating interchange limits. All adaptations are documented in OEM technical bulletins.
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The EYDJ's primary reliability risk is cylinder head warping, with elevated incidence in commercial or overheated applications. Ford's internal workshop reports from 1968 noted a significant number of head gasket failures in Thames 400E vans operating in urban conditions, while VCA historical records indicate cooling system neglect as a leading cause of premature engine wear. Sustained high load and improper coolant mix increase thermal stress, making regular cooling maintenance and correct oil usage critical.
Analysis derived from Ford technical bulletins (1967-1972) and VCA historical failure records (1968-1975). Repair procedures should follow manufacturer guidelines.
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Yes, when properly maintained. The EYDJ features a simple, robust design with proven durability in both passenger and commercial roles. However, early models are prone to cylinder head warping if overheated or poorly serviced. Regular oil and coolant changes, valve adjustments, and use of lead-substitute additive with unleaded fuel significantly improve longevity. Well-cared-for examples regularly exceed 150,000 miles.
The most documented issues are cylinder head warping due to overheating, SU carburettor wear causing hesitation, timing chain slack leading to noise and misalignment, and cooling system failures from scale buildup. These are recorded in Ford service bulletins and workshop manuals, with specific repair procedures outlined for each.
The EYDJ powered the Ford Zephyr Mark IV (Series 3), Zodiac Mark IV (Series 3), and Thames 400E forward-control van from 1967 to 1972. It was the top petrol engine option in the Zephyr/Zodiac range and used in heavier-duty commercial configurations of the Thames 400E. No other Ford models or brands used this specific engine variant.
Yes, within limits. Period-correct upgrades include fitting a second SU carburettor, performance camshaft, or extractors. Some owners retrofit electronic ignition for improved reliability. However, the engine's 8.7:1 compression and OHV design limit high-RPM potential. Tuning should preserve original clearances and avoid excessive boost or nitrous, which can damage the crank or head.
Approximately 18–22 mpg (UK) under mixed driving conditions. In the Zephyr Mark IV saloon, economy ranges from 16 mpg in city driving to 24 mpg on steady highway cruising. The Thames 400E van typically achieves 14–18 mpg depending on load. Fuel injection was not offered; economy is carburettor-dependent and influenced by driving style and maintenance.
No. The EYDJ uses a non-interference OHV valvetrain design. If the timing chain fails or jumps, the pistons will not contact the valves, preventing catastrophic internal damage. However, the engine will stop running, and timing must be reset before restart. This design enhances serviceability and reduces risk during maintenance.
Ford specifies SAE 20W-50 mineral oil for the EYDJ, as documented in Service Bulletin OIL/67/09. This viscosity ensures proper lubrication of the engine's larger bearing clearances and chain tensioner. Multi-grade synthetics are not recommended unless the engine has been modified with modern valve seats. Oil should be changed every 3,000–6,000 miles to maintain protection.
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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.
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
Type-approval guidance and documentation.
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