The Ford Kent Crossflow: A Timeless Classic

The Ford Kent engine, and in particular its famed Crossflow variant, is a powerplant that evokes a strong sense of nostalgia and respect within the automotive community. More than just a collection of metal and moving parts, the Crossflow represents a significant chapter in Ford's history, powering a generation of popular vehicles and continuing to find favour with enthusiasts today. Its enduring appeal lies not just in its robust design and accessible tuning potential, but also in its rich heritage and widespread application.

The Genesis: The Pre-Crossflow Kent Engine

To understand the success of the Crossflow, we must first look back to its predecessor, the original Ford Kent engine. Unveiled in 1959 for the Ford Anglia, this was a departure from the conventional engine designs of the era. It was an inline four-cylinder, overhead-valve (OHV) pushrod engine, featuring a robust cast-iron cylinder head and block. What set it apart was its 'over-square' cylinder dimensions – a bore of 80.96 mm and a stroke of 48.41 mm – which contributed to a surprisingly high power output for its time, developing 39 bhp at 5,000 rpm. The engine also boasted independent intake and exhaust ports, a design choice that facilitated efficient airflow. An innovative feature for its day was the externally mounted combined oil filter and pump unit, designed to simplify production and maintenance, making it a more practical and cost-effective option.

The original Kent engine was initially designated for the Anglia, but its versatility soon saw it adopted by other Ford models. With modifications to stroke length, it appeared in the Ford Consul Classic and Consul Capri, offering capacities of 1339 cc and 1498 cc. The iconic Ford Cortina also benefited from the Kent's adaptability, with versions ranging from 1198 cc to 1297 cc and 1498 cc finding their way into the Mk1 and early Mk2 models. Even the early Ford Corsairs were equipped with this engine. The 1500cc pre-Crossflow variant even served as the foundation for the renowned Lotus Twin Cam, with selected blocks being bored out to accommodate larger capacities. The naming of the engine family as 'Kent' is attributed to Alan Worters, Ford's Executive Engineer for Power Units, who resided in the English county of Kent, across the river from Ford's Dagenham plant. While the name was officially adopted to include the improved '711M' blocks with their square main bearing caps, it broadly came to encompass all engines in the family, including the earlier pre-711M units.

Key Applications of the Pre-Crossflow Kent:

The pre-Crossflow Kent was a workhorse, found in a variety of popular vehicles:

• Ford Anglia
• Ford Cortina (Mk1 & early Mk2)
• Ford Consul Classic and Consul Capri
• Ford Corsair
• 107E Ford Prefect
• Marcos 1500 GT
• Otosan Anadol 1.2 L – 1.3 L (1966–1984)
• TVR Grantura
• Lotus Mk.VII

The Evolution: The Ford Crossflow Engine

The year 1967 marked a significant redesign, giving birth to the engine that would become arguably the most prolific and recognisable of the Kent family: the Crossflow. The key innovation was the adoption of a 'cross-flow' cylinder head, a design where the intake and exhaust ports were positioned on opposite sides of the cylinder head. This improved the engine's breathing efficiency and performance. The Crossflow went on to power a wide array of Ford vehicles, including the smaller-engined versions of the Ford Cortina and Ford Capri, the first two generations of the European Ford Escort, and for a brief period, the North American Ford Pinto (1971-1973).

A notable feature of the Crossflow was the shift in combustion chamber design. Instead of being solely within the cylinder head, the combustion chamber was integrated into the top of the piston. This 'Heron' type combustion chamber design, with its flat cylinder head, allowed for different piston bowl designs to be used for various engine capacities (such as 1098 cc and 1298 cc) in blocks like the 681F and 701M. The more robust 1599 cc 691M block, which featured stronger 'square' bearing caps (later refined in the 711M block), used smaller combustion chambers in a near-flat head, with the majority of the volume residing in the piston bowl. The introduction of the A711 block (1298 cc) and the A711M block (1599 cc) in 1970 brought further improvements, including thicker block walls, the aforementioned square main bearing caps, larger diameter cam followers, and wider cam lobes. The A711M block also had a slightly taller deck height. These enhancements significantly boosted the reliability and durability of the engines, with the '711M' blocks becoming particularly sought after for their strength.

BIP Engines: A Closer Look

The term 'BIP' engine, often associated with the Ford Mk2 Cortina, refers to a specific characteristic of the Crossflow design. It signifies the 'Bowl In Piston' combustion chamber. These engines also differed from their pre-Crossflow counterparts by having the carburettor on the left side of the engine and the exhaust manifold on the right, hence the 'crossflow' nomenclature. This configuration was a key differentiator and contributed to the engine's improved efficiency.

Crossflow Specifications and Tuning Potential

The Ford Crossflow was produced in various capacities, commonly including 940 cc, 1098 cc, 1298 cc, and 1599 cc. In South Africa, it was a popular choice for the Ford Cortina (Mk II through Mk V) and the Ford Sierra, both in their 1.6-litre configurations. The engine's inherent robustness and widespread availability have made it a favourite for tuners and modifiers. Achieving 'GT spec' is a popular upgrade path, typically involving the largest capacity block (often the 1599 cc 711M), slightly larger valves (often facilitated by a performance cylinder head), a performance camshaft, a free-flow exhaust system, and a twin-choke Weber carburettor. Such modifications can typically yield around 80-90 bhp. Stepping up to a more aggressive camshaft, such as a Kent BCF2 or 224, can push power figures towards 110 bhp. For more serious tuning, reinforcing the valvetrain with steel posts, spacers, and rocker shafts is crucial to handle the increased stresses from high-lift cams, heavy-duty valve springs, and higher RPMs. A double timing chain kit is also recommended to ensure reliability under these demanding conditions. Upgrades like ARP rod bolts and a one-piece steel front pulley further enhance the engine's durability for performance applications.

The versatility of the Crossflow extended beyond Ford's own lineup. It powered the Reliant Anadol from 1968 to 1984 and was a popular choice for specialist manufacturers like Morgan (on the Morgan 4/4), Caterham (on the Caterham 7), and TVR (in models such as the Grantura, Vixen, and 1600M). Its reputation as a reliable, tunable, and relatively simple engine has made it an enduringly popular choice for kit car builders, not just in the UK but across the globe.

Crossflow Applications:

• Ford Cortina (smaller-engined versions)
• Ford Capri (smaller-engined versions)
• Ford Escort (Mk1 & Mk2 European)
• Ford Pinto (North American, 1971-1973)
• Ford Cortina (South Africa, 1.6L Mk II-V)
• Ford Sierra (South Africa, 1.6L)
• Reliant Anadol (1968–1984)
• Morgan 4/4
• Caterham 7
• TVR Grantura, Vixen, and 1600M

Why is the Kent Crossflow Still Popular?

The enduring popularity of the Ford Kent Crossflow can be attributed to several key factors:

• Historical Significance: It powered a generation of iconic vehicles, making it a piece of automotive history.
• Robust Design: The core engineering is sound, particularly the later '711M' blocks, offering good durability.
• Tunability: The engine responds very well to modifications, allowing for significant power increases from relatively simple upgrades.
• Availability: Parts are still relatively easy to find, and the engines themselves can often be sourced affordably.
• Simplicity: Its OHV pushrod design is less complex than many modern engines, making it easier for home mechanics to work on.
• Versatility: It has been fitted into countless different vehicles, especially kit cars, showcasing its adaptability.

Frequently Asked Questions

Is the Ford Kent Crossflow a good engine?

Yes, the Ford Kent Crossflow is widely considered a very good engine, particularly for its era. It's known for its robustness, ease of maintenance, and excellent tuning potential. While not the most powerful from the factory compared to some contemporaries, its ability to be upgraded reliably makes it a favourite among enthusiasts.

What does 'Crossflow' mean in relation to the engine?

'Crossflow' refers to the design of the cylinder head where the intake ports and exhaust ports are located on opposite sides of the head. This allows for a more efficient flow of the air-fuel mixture into the cylinders and exhaust gases out, improving performance.

What is the difference between a pre-Crossflow and a Crossflow Kent engine?

The main difference lies in the cylinder head design. The pre-Crossflow has both intake and exhaust ports on the same side of the head (a 'reverse-flow' configuration), while the Crossflow has them on opposite sides. The Crossflow also introduced changes to the combustion chamber design, moving it partly into the piston.

What are the common capacities for the Ford Crossflow engine?

The most common capacities for the Ford Crossflow engine are 1098 cc, 1298 cc, and 1599 cc.

Can you still get parts for a Ford Crossflow engine?

Yes, parts for the Ford Kent Crossflow engine are still widely available, both new and used, from specialist suppliers and classic car parts retailers.

What is the typical power output of a standard Ford Crossflow?

A standard Ford Crossflow engine typically produced between 50 bhp and 75 bhp, depending on the specific variant and carburetion. However, as mentioned, tuning can significantly increase this figure.

In conclusion, the Ford Kent Crossflow engine is far more than just an engine; it's a testament to clever engineering, adaptability, and enduring appeal. Whether found in a classic Cortina or a custom-built kit car, its distinctive character and mechanical integrity ensure its place in automotive history.