Ford Kent engine

The name

This series of engines became known as the Kent engine because Alan Worters, the company's Executive Engineer (Power Units), lived across the river from Ford's Dagenham plant in the English county of Kent.

Originally within Ford, it is said that the Kent name was actually born with the A711 and A711M blocks (commonly called the 711M block) with square main bearing caps for the Crossflow series, which represented a vast improvement in the durability of the engines. However, the name caught on to be used outside the company to include pre-711M engines as well.

Pre-Crossflow

The original OHV three main bearing Kent engine appeared in the 1959 Anglia with a capacity of 996.70 cc developing 39 bhp (29 kW) at 5,000 rpm - unusually high for the time. With a 3-3/16 in (80.9625 mm) bore and 48.40 mm (1.906 in) stroke, combined with independent (non-siamesed) four intake and four exhaust ports, it was a departure from traditional undersquare English engine design.

The same engine, with its bore unchanged, but with longer 65.00 mm and 72.75 mm stroke and thus larger capacities were subsequently used in the Ford Consul Classic (1339 cc) and Consul Capri (1339 cc and 1498 cc), the Mk1 and early Mk2 Cortinas (58.20 mm stroke 1198 cc, 63.00 mm stroke five main bearing 1297 cc and the 1498 cc), and the early Corsairs.

In addition to its 'over-square' cylinder dimensions, a further unusual feature of the Kent engine at its introduction was an externally mounted combined oil filter/pump unit designed to facilitate efficient low-cost production and easy maintenance.

The engine is now referred to as the pre-crossflow Kent, in reverse-flow cylinder head configuration with both the inlet and exhaust being on the same side of the head.

Applications:

The Pre-Crossflow Kent engine was also used by Lotus on Lotus Mk.VII.

Crossflow

A 1967 redesign gave it a cross-flow type cylinder head, hence the Kent's alternative name Ford Crossflow. It would go on to power the smaller-engined versions of the Ford Cortina and Ford Capri, the first and second editions of the European Escort as well as the North American Ford Pinto (1971, 1972 and 1973 only). In South Africa it also powered the 1.6 L Mk II, Mk III, Mk IV, & Mk V Ford Cortina and 1.6 L Ford Sierra.

The Crossflow featured a change in combustion chamber design, using a Heron type combustion chamber in the top of the piston rather than in the head. The head itself was flat with each engine capacity (1098 and 1298 cc) featuring different pistons with different sized bowls in 681F and 701M blocks. The 1599cc 691M block had the stronger 'square' bearing caps later used in the 711M, and small combustion chambers in the near-flat head (the bulk of the volume being in the piston bowl). In 1970, the new A711 block for 1298 cc and A711M block for 1599 cc were introduced with thicker block wall, square main bearing caps, large diameter cam followers and wider cam lobes, with the latter block having a 7/16" taller deck height, together with a return to the flat head. These changes represented a significant improvement in the reliability of the engines, and the blocks are commonly referred to as '711M' blocks.

The Ford Crossflow engine (1298 cc and 1599 cc) also powered the Reliant Anadol (1968–1984). Other makes such as Morgan used the Crossflow on Morgan 4/4, Caterham on Caterham 7, and TVR used the engine in the Grantura, Vixen, and 1600M. It has been fitted in countless other applications as well, being a favourite of kit-car builders not only in Great Britain.

Destined for the American market, beginning with the 1977 model year, the Valencia plant began manufacturing a 1.6L, 63BHP, five-main bearing version that included a low emission bowl-in-pistons combustion chamber design based on the Crossflow head, and was equipped with a Dura-Spark electronic ignition. This version was used in the short-lived (1977-1980) USA-market Mk1 Fiesta. This engine would be later used in the XR2 version of the Mk.1 Fiesta, using the US 1600 bottom end and GT spec head and cam. 1.3L versions of the Mk I Fiesta also used the Crossflow, as opposed to the Valencia (see below).

Valencia

A redesigned version of the Kent engine was conceived to suit transverse installation in 1976, primarily for the Mk.1 Ford Fiesta, although base model versions of the Escort Mk.III also used the engine. This derivative would go through two major revamps in 1988 and 1995 and would be a mainstay of Ford's entry level compact range for nearly 25 years.

Original Valencia (1976-1988)

The Valencia was initially available in 957cc (in both high compression and low compression versions ) and a high compression 1117cc version.

For adapting the Kent Crossflow for front wheel drive the ancillaries were repositioned, and the cylinder block shortened by 30mm. This decision was taken in order for the engine to fit transversely across the Fiesta engine bay, whilst still allowing the transmission unit to be comfortably removed for clutch replacement. This difference however means that very few parts of the Valencia engine are interchangeable with a Crossflow. Interestingly however, Ford ended up installing the Crossflow engine into the Fiesta anyway, when the market demanded a 1.3L capacity, and later a 1.6L version for the North American market models - ultimately the 1.6L Crossflow also was used in the Mk1 Fiesta XR2 when the North American market Fiesta ceased production in 1980.

In addition to these changes, the Valencia featured a new transmission flange to suit the BC4/5 transaxle and the cylinder head redesigned using flat-top pistons and the traditional combustion chamber in the head. Although internally named within Ford as "L-Series" it became better known as the Valencia to the wider world, after the new Spanish factory built for its manufacture, but eventually the name was officially adopted by Ford as well - although in sales literature it was always called simply OHV. It was available in 957cc and 1117cc versions.

A five bearing 1.3 L (1296cc) version of the Valencia became available in 1986 for the facelift "Erika-86" version of the Escort and Orion, replacing the similarly sized CVH unit, which increased to 1392cc for higher specification models. The cylinder heads and pistons were modified in 1986 for unleaded fuel and the cams changed to meet the new European emissions standards along with the addition of electronic ignition.

HSC (1988-1997)

In 1988 the second generation of the Valencia unit was launched to meet with tightening European emissions legislation. The redesign included an all-new cylinder head with reshaped combustion chambers and inlet ports, and a fully electronic distributorless ignition system. The engine was renamed the Ford HSC (standing for High Swirl Combustion), although some internal Ford service publications call it the Valencia-HSC in reference to its heritage.

It first appeared in 1118cc and 1297cc guises on the Ford Escort and Orion for the 1989 model year, and on the then new Ford Fiesta Mark III the same year, which also offered a smaller 999cc version to replace the older 957cc Valencia.

The HSC is distinguishable from the original Valencia by the "mirrored" arrangement of the spark plugs (they appear to "point inward" towards each other), the block, head and rocker cover being painted gray (the original Valencia was painted black), the presence of a crankshaft position sensor just above the starter motor, and the absence of a distributor drive on the rear face of the cylinder block.

Endura-E (1995-2002)

The final redesign came in 1995, with the launch of the fourth-generation Ford Fiesta. This edition was effectively another redesign of the Valencia/HCS derivative, known as the Endura-E, and featured many revisions to combat noise and harshness, including a thickened cylinder block. This engine would also be used in the Ka until 2008 and the 1.3 Escort until 2002.

This type of engine still has tappet noise even after adjustment. This noise is said to come from the cams due to incorrect valve setup (when setting valve clearance each cylinder must be set to TDC) or from age and use of incorrect oil grade. The correct oil grade is 5W-30 semi synthetic oil. Another reason is the large tappet clearance on the exhaust valve. This could of course be reduced to lower the noise level but the engine would then suffer from a rough idle and usually stalled.

Despite Ford's engines being well regarded for their ease of service, the Endura-E has a very awkward placing for its oil filter, at the back of the engine and facing from left to right rather than pointing downwards or out, this being a leftover from the original Kent which was normally mounted longitudinally for rear-wheel drive. This mounting position makes it very difficult to access from underneath the car (without a mechanic's ramp), and despite being very short, the can-type oil filter still manages to protrude past the tip of the adjacent starter motor, meaning it is very difficult to remove using chain-type grips.

Motorsport

Ford Kent engines had a profound influence on motorsport, possibly more so than any other mass-produced engines did in the history of motorsport. Satta/Hruska designed Alfa Romeo 750/101 1290cc DOHC unit, and Alex von Falkenhausen designed SOHC 1773cc BMW M118 engine may have had similar influence on the motorsport scenes in Italy and Germany respectively, but not even comparable internationally.

Lotus used Ford Kent engines on Lotus Mk.VII to establish its corporate foundation, and subsequently used most of the Cosworth early racing engines for the legendary success in motorsport. Lotus also built the successful Lotus TwinCam engine for Lotus Elan on the Kent block, crank and conrods.

Cosworth's initial products were all Ford Kent based, and the later SCA, FVA and the BD series used Kent blocks to dominate many FIA categories including Formula 2 and Formula 3.

In addition, many respected racing engine builder/tuners, such as Holbay, Vegantune, Novamotor, Brian Hart, Richardson and Wilcox owe their foundations to the Ford Kent-based engines.

Furthermore, the Kent Crossflow engine was used as the regulation engine in Formula Ford, although it was originally proposed to be the pre-crossflow 1498cc Cortina GT unit in 1967 (before the establishment of the series). In Europe, Formula Ford switched to the Zetec, but American Formula Ford continued to be Kent-powered until 2010; the SCCA having approved the use of the Honda L15A i-VTEC for Formula F.

As it was nearly impossible to succeed in motorsport without some activities in Formula 2, 3 or Formula Ford, most of the well-known racing drivers in the 1960s, 1970s and 1980s owe their careers to Ford Kent to some extent, and the current historic motor racing depends heavily on the Kent-based engines.

On 16 October 2009, Ford announced that it would be putting the Kent block back into production in order to supply the historic racing community with spares. According to a Ford press-release, engineering work began at Ford Racing's Performance Parts division in the US, with sales scheduled to start in 2010. Link to Kent block in Ford Motorsports Parts online catalog

The 1300cc was the engine of choice for BriSCA F2 until a rule change about carburettors pushed people towards the 2000cc Ford Pinto engine.

Trivia

Harry Mundy designed the Lotus TwinCam engine for Colin Chapman, who needed the replacement for the Coventry Climax FWE engine used in Lotus Elite. As Keith Duckworth and Mike Costin, the co-founders of Cosworth, used to be Lotus Development Ltd employees, the initial racing adaptation of Lotus TwinCam was carried out by Cosworth, and the Kent block Cosworth SCA was designed using the basic SOHC reverse-flow cylinder head configuration of the FWE. Due to Mundy being also the co-designer of the FWE, the Kent block Lotus TwinCam initially used the cam profile of the FWE, and shared the same valve clearance adjustment shims with Coventry Climax FWA, FWB, and FWE in production.

The Endura-DE and Endura DI diesels bear no similarities to their petrol namesake. Ford did produce a diesel HCS engine.