A missed opportunity or a masterpiece of compromise? We look at the unassuming little engine that drove the Fiesta’s success.
CAR March 1974 was confident in its prediction about the Fiesta’s engine; “it is a completely new water-cooled, in-line four with single overhead cam and Heron head. It will come in two sizes – a little over 900cc and 1090cc for the top of the range model.” As we now know, the “scoop report” could scarcely have been more wrong, but it is easy to understand the reasons for their conjecture. The engine was to be built in a new plant in Spain, on all-new tooling. The Heron “bowl-in piston” head was a feature of the existing Kent and Essex engines. The new car’s competition might have given some clues to the level of sophistication Ford would be aiming for. The Fiat 127 and Renault 5 used 1950’s pushrod designs which did a far better job than might have be expected.
The Peugeot 104’s all-new, all-aluminium ohc engine was way beyond the level of sophistication Ford were able or willing to achieve in a mass-produced engine in the mid-‘70s. Indeed its intricacy suggests something which could have originated in the watches and micromechanics valley stretching from Switzerland into Besançon, not so far from Sochaux.
A more realistic benchmark would be VW’s EA111 engine, in production since early 1974. This was an iron-blocked near-square in-line four with an alloy crossflow head and a belt driven overhead camshaft.
The engine which arrived with the first generation Fiesta may have surprised many. With its iron head and block, pushrod valve operation, and three main bearing crankshaft it appears to belong more in the mid-fifties than the enlightened 1970s.
The Seidler book consistently infers that it is an adapted version of the Kent ohv unit first seen in the 1959 Anglia. It’s true that the Kent served as the template for the engine officially known as ‘L-series’ (The ‘Valencia’ toponym was officially adopted after years of informal use), but it was altered in so many ways that it is a different engine with virtually no interchangeability of parts with the older engine.
The shock is that the adaption process seemed so regressive. Pushrod operated valves and an iron cylinder head might be expected, but three main bearings instead of five seems merely tight-fisted. The justification given was that as the block was shortened – bore centres were drawn closer in line with a reduction of the bore dimension from 81mm to 74mm – the block was stiffer and the two intermediate main bearings were unnecessary. It took ten years for mean old Ford to relent and give the newly introduced 1.3 litre Valencia five main bearings.
The 1976 abridged Kent engine was 30.5mm shorter and 7kg lighter than the 81mm bore original edition. The weight reduction seems unimpressive considering the level of re-working, but with a target capacity of 400,000 engines per year, must have saved a considerable quantity of iron.
There’s a myth that the Fiesta’s engine is a revived version of the 1959 Anglia unit. It’s not, but the confusion may arise from the 1976-on Kent being commonly referred to as the “Crossflow”, and the Fiesta engine as the “OHV”, although it also has a crossflow head; the Anglia’s was reverse-flow.
Ford made a perfectly rational choice in developing a cheap, simple engine for their B-sector car. The R5 and 127 were not held back by their ageing engines, and when more power was called for, the full-size Kent, and eventually CVH were there to do the job.
There are other explanations for Ford’s conservatism in the engine matter. The 1959 Kent had been something of a bullseye; short stroke small capacity engines with eight port heads and string bottom ends were a rare commodity, and delighted racing engine builders and fleet managers alike.
Dagenham built on its success with five main bearing 1300 and 1500 cc versions, followed in 1967 by a major rework, with a crossflow head layout, bowl-in piston combustion chambers and across the board adoption of the five main bearing bottom end.
The Kent was a triumphant achievement for a company which only abandoned side valves for its smallest engines in 1959, but Ford’s other European engines of the period were less of an ornament to their reputation. The 1965 Essex V4 was unrefined, inefficient, and prone to head gasket failure – and there were two to fail. Its 1969 in-line replacement, the Pinto OHC unit showed more promise, but the all-iron engine’s clever valve-gear design quickly developed a bad reputation for premature wear. This was later mitigated by positive lubrication and nitriding of wear-prone components.
Linking the Fiesta’s engine with Ford’s most trusted European power unit looks like a sound managerial decision, but there wasn’t much Kent left in the Valencia, or L-Series, to give it its Sunday name.
The biggest Valencia departure was the abandonment of the Heron head in favour of a wedge shaped in-head combustion chamber with inclined valves, following Renault and Fiat practice at the time. In the Ford context this is surprising. The bowl-in piston combustion chamber is particularly effective in very oversquare engines, as it overcomes the problem of quench surfaces, areas of the combustion chamber which remain cool enough to retain “wet” fuel which makes its way to the exhaust unburnt. The 957cc and 1117cc Valencias were still well oversquare, but the volte-face suggests that Ford were already embracing the new emissions-led thinking which put effective combustion chamber design ahead of maximisation of valve areas.
What we have is an engine of strictly limited ambitions. There was no need for room to expand since the Kent, and later the CVH, could fulfil the 1300cc and upwards jobs. The early global ambitions for the Bobcat project most probably played some part in the conservative specification of its engine. Pushrods and all-iron construction are well suited to labour-intensive low-precision manufacturing. The Almusafes plant was as advanced as the best in Europe, but in the context of Ford’s ambitions to conquer Spain the simplicity of the engine it produced made eminent sense. Ford had to establish a dealer network from a base of zero. A powertrain as intricate as the Peugeot XA, would have been disadvantaged in a country familiar only with the worthy pushrod engines made by SEAT, Renault, Simca, and BMC.
Capacities were set as a tax-friendly 957cc, and a longer stroke 1.2 litre, which would have given a useful advantage in the sector. Within weeks of the Yom Kippur war in October 1973, Ford management took a decision to reduce the capacity of the larger Valencia to 1117cc. At launch in September 1976, the 957cc units were offered in 40 and 45bhp tunes, while the 1117cc version gave 53bhp, well up to the standards of its rivals. Those lusting after real Kent power had to wait until October 1977 for the 66bhp 1300, available only in the S and Ghia.
So was the Valencia a bad engine? Not at all. It was designed in the image of the heroic little four cylinder engines which mobilised much of Europe, and at least on that continent, it outlived the disappointing CVH by ten years, eventually bowing out in 2002, to be replaced by the rather good Rocam, an 8 valve OHC unit with capacities from 1.0 to 1.6 litres, built in Brazil and South Africa.
In between, the Valencia demonstrated an ability to answer every question it was asked, much in the manner of the Austin A series and Renault Cleon. It was never going to be the most refined, powerful or efficient in its class, but it was dependable and easy to fix in the rare event of failure.
Of all the Valencias, my favourite is the humble 957. It has a mere 45bhp at 6000rpm. That last number is telling. The little Valencia has shares with the VW flat fours the ability to be driven flat-out for as long as conditions will allow without feeling as if it will explode at any time. It’s a short-stroke thing. The piston speed is lower than an equivalent undersquare engine, and the changes in piston direction happen less violently. We should regret that the predominance of long-stroke engines, and the petty strictures of the law have made such simple pleasures a thing of the past.