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 (Series 3), Zodiac Mark IV (Series 3), and Thames 400E commercial variants, the EYDJ was engineered for relaxed cruising and durability in both passenger and light-commercial applications. Its design prioritised mechanical simplicity and ease of service, with cooling managed via a conventional radiator and belt-driven water pump. Emissions control was minimal by modern standards, reflecting pre-regulatory era engineering practices.
One documented service concern is cylinder head warping under sustained high load or incorrect cooling system maintenance, noted in Ford Service Bulletin 68/21. This issue stems from the engine’s thin-cast head and sensitivity to overheating, particularly in commercial variants with frequent stop-start operation. Later production batches included revised head bolt torque sequences to improve sealing integrity.
Production years 1967–1972 predate mandatory European emissions standards; no Euro classification applies (VCA UK Type Approval Archive, 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 OHV inline-six design provides smooth, linear power delivery well-suited to heavy saloons and commercial chassis, but requires regular valve clearance checks every 6,000 miles to maintain performance. SAE 20W-50 mineral oil is essential due to the engine’s clearances and lack of modern anti-wear additives in original design. Overheating must be avoided—especially in stop-start operation—as the thin-cast cylinder head is prone to warping. The SU carburettor demands periodic adjustment and float-level checks to prevent running issues. Cooling system maintenance, including thermostat replacement and radiator descaling, is critical for long-term reliability. Use of lead-substitute additive is recommended when running unleaded fuel to protect valve seats.
Oil Specs: Requires SAE 20W-50 mineral oil (Ford Service Bulletin OIL/67/09). Multi-grade synthetics not advised without valve seat modification.
Emissions: No Euro standard applies; engine predates emissions legislation (VCA Historical Archive, Pre-1970).
Power Ratings: Measured under SAE Gross standards. Output reflects carburetted, non-catalysed configuration (Ford Brochure F-67-Zeph-03).
Ford UK Workshop Manual No. SM-4023-3 (Zephyr Mark IV Series 3)
VCA Historical Type Approval Archive (Pre-1970 Vehicles)
SAE International: J272 Engine Power Measurement
Ford Engineering Drawings ED-Z6/40H
Ford Service Bulletins 68/21, OIL/67/09, PET/67/05
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.
Locate the engine number stamped on a machined pad at the front of the cylinder block, just below the cylinder head (Ford TIS SM-4023-3). The prefix "EYDJ" identifies this engine variant. Visually, it can be identified by the single SU HD8 carburettor, exposed valve cover, and absence of emission control hardware. Critical differentiation from the smaller 3.0L EV30H engine: EYDJ has a longer engine block and distinct exhaust manifold routing. Service parts require casting number verification—cylinder heads from pre-1969 and post-1969 models differ in port design per Ford Engineering Drawing ED-Z6/40H Rev. 4.
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.
Find answers to most commonly asked questions about FORD EYDJ.
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