Engine Series – Ford Cross Flow

The Lotus engines Series

Ford Cross Flow engines: Cross examination


“You’re looking at the most ubiquitous engine ever built. If ever an engine was a blank canvas to be painted with whatever purpose a car designer needed .Ford of Britain’s small block, ohv straight four was it”


The engine series are neither technical treatise nor Haynes Manuals. This information is readily available in published form or on the net.

Rather our study concentrates on how and why Chapman and his colleagues’ selected engines and their contribution to Lotus success and sales.

In his specification of major mechanical components Chapman added both performance to a sophisticated chassis and extraordinary added value.

Lotus were not a major engine manufacturer until quite late on .Despite this they used and adopted a range of mainstream engines to extraordinary effect.

Chapman and Lotus practice provides inspiration for all Industrial Designers /Specialists in their search for urgency and added value.

Our study focuses heavily on the fitment of these engines along with a visual representation. We debate the appeal to owners / racers and the beneficial publicity accredited to the manufacturers.

We believe that subscribers will be well able from this base line to research specific topics according to their needs.

Subscribers might like to see directly related and structured A&R articles complementary with this piece: –

  • Lotus Power Plants
  • Engines that powered Lotus including Austin, MG, Ford’s, Cosworth, BMW, Coventry Climax
  • Ford Lotus Twin cam and Vegantune
  • Ford Gearbox types
  • Lotus and Formula Ford
  • Lotus Seven – various articles and related sales materials
  • Lotus Seven – Form and Function

Crossflow [edit] from wiki:-

The editors have examined many sources but wiki has advantage of brevity with reasonable comprehensiveness for our purpose.

“A 1.6 litre Kent Crossflow (711M block) in an Anadol FW11 prototype

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 cc and 1298 cc) featuring different pistons with different sized bowls in 681F and 701M blocks. The 1599 cc 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).”

Cross flow from Weale

“ a redesign in 1967 created the definitive pushrod Ford engine –the “cross flow” of 1300 and 1600 cc ……..as fitted to series 3 & 4 Seven , developed 86bhp in unmodified form , with a single twin coke carburetter –a respectable output for a very simple though well developed cast –iron engine , which was practically indestructible and not unduly heavy “

Simplicity and sophistication

The Ford cross flow possessed these qualities.

Time and time again it’s possible to see planning in Ford concepts likely to be of benefit to owners and the mass market.

The cross flow engine was economic in manufacture impacting on cost reduction.

It was simple and accessible. Maintenance and servicing were easily facilitated.

The hidden sophisticated part of the cross flow was the:-

Heron Head.

The advantages / disadvantages listed from the net are: –

  • Advantages include: simplicity of manufacture; compact dimensions; accuracy of the flat machined surface; simplified valve-gear; efficient combustion with good fuel economy.
  • Disadvantages include: the greater size and weight of each piston; volumetric efficiency poorer than conventional cylinder heads.

The Cross flow and the Lotus Seven

A&R articles deal with the Seven in some detail. We suggest reference to these for a fuller appreciation of the interrelationship between the Seven and the cross-flow engine.

In particular we suggest looking at “Seven –form and function” to see the relative ease which this unit could be incorporated.


Figure 1. Editors sketch Ford Crossflow installed in Lotus Seven


Figure 2.editors sketch/diagram of cross flow with approximate dimensions.see Lotus Seven Form and Function for better appreciation of scale and fit


Figure 3.Editors photographs of Ford Cross flow engine 1300 cc


Figure 4.Same engine seen from head on.


Figure 5editos sketch diagram of Ford crossflow and approximate dimensions


Figure 6.editors photographs cross flow in kit car


Figure 7.editors photograph cross-flow in editors Ford special

Seven with cross flow from Reece

Seven Model Series 3:1300/1600
Engine Ford 225 E Kent crossflow
Capacity 1297/1598cc
Bore x Stroke 80.96 x62.99 /80.96 x 77.62mm
Induction single Weber 32 DFM carburetter
Compr’Ratio 9.2 to 1 / 9.0 to 1
Max.Power 72 bhp [54kW]@6000 rpm /84 bhp [63kW]@6500
Max.Torque 68lb ft [92Nm]@4000 rpm /91lb ft [123Nm]@3500
Gearbox Ford Cortina 116E four speed
Brakes Girling 9 in disc front ,8in drums rear
Steering Triumph Herald Rack and pinion
Weight 1210 lb [549kg]
Top Speed 100/104mph /161/167 kph
0-60 mph n/a 7.7 sec
50-70 top n/a 7.8 sec
No.Produced approx .340 [all S3]

Learning Opportunities

Our learning /educational opportunities are intended to be challenging thought provoking and requiring additional research and/or analysis.

These opportunities are particularly designed for a museum/education centre location where visitors would be able to enjoy access to all the structured resources available in conjunction with any concurrent exhibition. The following might be appropriate: –

  • How did the Kent engines evolve?
  • How did Cosworth adapt the engine?
  • What were Ford’s engine production techniques associated with whole cross flow engine?
  • What particular qualities are associated with the cross flow?
  • What made them better than rivals?
  • Which other mass production engines have been adapted /improved like Ford – consider European and American context
  • Which motor racing /competition events and formula did the cross flow compete?
  • List the specialist marques and kit cars that have adopted the cross flow
  • List major tuners and aftermarket specialists catering for cross flow
  • How many cross-flow engines were manufactured and to what markets?
  • Calculate the number of Lotus sold with cross flow engines


Figure 8.editors photograph cross flow in Caterham Seven

Exhibitions, Education and Economics

In the museum context the editors believe that commercial considerations are both necessary and complementary with its educational objectives.

For these reasons our suggested outline Business Plan includes provision for promoting products and services which share Chapman’s ideals of mechanical efficiency and sustainability. In addition we propose merchandising that explain and interprets the social and cultural context of Chapman’s designs in period. It’s suggested there will be catalogue for on line purchasing.

The following might be appropriate:-

  • Ford Cross flow: Cross examination
  • Ford Cross flow: Cross passage
  • Ford Cross flow: Cross over value
  • Ford Cross flow: Cross wise
  • Lotus and Ford Cross flow: Cross-mix
  • Lotus and Ford Cross flow: Cross blend
  • Lotus and Ford Cross flow: Converge and hybridise
  • Lotus&Ford Cross flow:Cross-fertilise
  • Ford Cross flow: The Market cross


The Ford cross flow engine in 1,300 and 1,600 cc capacities engine powered Lotus.

It continued in the Caterham Seven.

It therefore powered racing and road cars.

It was a superb piece of industrial design; functional and utilitarian.

It was successful in racing e.g. Formula Ford gaining publicity and inspired modification, tuning and a generation chassis designers.

The engine was attractive to owners and generated sales. Exports were possible because of the international spare’s availability.

These mass-produced engines were robust, inexpensive, widely available and spawned aftermarket components industry. Furthermore, they invited experimentation, and helped facilitate competition and design diversification. Thus assisting and elevating British motor racing: design, engineering, manufacture and of course drivers.

In the case of the Ford cross flow it formed a dedicated race Formula in the 1970’s that continues to the present time. [Formula Ford] Lotus being a major beneficiary along with Ford as the positive publicity helped road car sales reputationally.

The engine has continuing legacy and relevance and being such a significant piece of industrial design is fully worthy of analysis and appreciation.

Added value is an extremely important aspect of Industrial Design, Chapman exploited to maximum effect and this engine helped sell the Lotus Seven. It was the basis of further tuned engines and helped provide continuity through the Caterham Seven. The principles of adding value are significant for a young entrepreneur with low capital wishing to enter the market.


Legendary Car Engines. Simister. Motorbooks.2004.

ISBN: 0760319413

The Lotus Book.Taylor.Coterie.

Lotus Seven.Weale.Osprey.

See exhaustive bibliography with A&R items on the Lotus Seven

Please note the editors of the A&R attempt to give the broadest spectrum of references but not all are available for consultation in an article. However by noting their existence it may assist students in their research.

*Items in italics non A&R library books.