Guide: Ford Escort Mk1 RS1600
Background
Released in January 1968, the Twin Cam was the first true high performance Mk1 Escort. It combined the venerable DOHC 1.6-litre engine that had powered the legendary Lotus Cortina with the smaller and lighter bodyshell of the recently introduced Mk1 Escort.
Like the Lotus Cortina, the Escort Twin Cam was conceived primarily as Ford’s premier motor sport weapon for the Group 2 class of international competition. In order to qualify, 1000 examples had to be completed within a twelve month timeframe; Ford accomplished the task by spring ‘68 and Group 2 homologation was approved from May 1st. By this time the Twin Cam had also been approved for the Group 3 Grand Touring class with its 500 car production requirement.
Over the next couple of years, the Escort Twin Cam went on to achieve great things in Touring cars and rallying. However, during 1969 it became apparent that the Lotus Twin Cam engine, which had first appeared on the scene way back in 1962, was approaching the end of its frontline motor sport career.
Around this time, Ford was also in the process of establishing a dedicated new Advanced Vehicle Operations department (AVO) in Aveley, Essex.
Ultimately, the AVO division would be staffed by 350 personnel who were tasked with the development and manufacture of Ford’s high performance models. By late 1970, all such cars would be constructed at Aveley as opposed to the Halewood plant in Merseyside which was struggling to integrate comparatively low volume models with the day-to-day churn of mainstream variants which were built in comparatively vast quantities.
Although not yet geared up for production, the AVO team was tasked with creating a replacement for the Escort Twin Cam during the summer of 1969. Ford wanted production to begin in early 1970 which meant assembly would provisionally have to take place at Halewood until the AVO plant at Aveley was ready.
When it came to sourcing a new power unit for the Escort Twin Cam’s replacement, there was only one place the fledgling AVO team needed look: Cosworth Engineering.
Thanks to funding from Ford UK, Cosworth had developed the venerable DFV V8 which had taken the world of Formula 1 by storm since its arrival in early 1967.
Prior to this, Cosworth had also developed a Ford-based Formula 2 engine, the FVA, which not only served as a test-bed for the DFV but also became the premier engine of the 1.6-litre F2 era which had kicked off in 1966.
Ford thought a productionised version of the four cylinder FVA would be ideal for the Escort Twin Cam’s successor and accordingly a revamped iteration suitable for road use was commissioned. The Cosworth BDA motor (Belt Drive A-series) was the result and effectively combined a crossflow Kent block with a state-of-art 16 valve head.
The BDA-powered Escort was dubbed RS1600 and the first example rolled out of Ford’s Halewood plant on January 11th 1970. Customer deliveries of the new Rallye Sport Escort began that spring, Group 2 homologation was approved on September 1st and production was subsequently transferred to AVO’s new Aveley plant with the first example emerging from here in early November.
Engine / Gearbox
Under the RS1600’s hood was the first iteration of Cosworth’s legendary BDA motor which went on to have such a stellar motor sport career.
The cast-iron Kent crossflow cylinder block was essentially a standard production item while up top was Cosworth’s light alloy DOHC head with four valves per cylinder. Unlike the FVA upon which it was based, the BDA used a toothed belt to drive the camshafts as opposed to the expensive gear-driven arrangement of the FVA.
Displacement was 1601cc thanks to a bore and stroke of 80.98mm and 77.72mm respectively.
As per the Twin Cam, a special four-to-one exhaust manifold was fitted along with an oil cooler.
With a 10.0:1 compression ratio and two Dellorto 40 DHLA sidedraught carburettors, peak output was 115bhp at 6500rpm and 110lb-ft at 4500rpm.
This rose to 122bhp at 6500rpm if the optional Weber 40 DCOE carburettors also homologated were installed.
For comparison, the outgoing Escort Twin Cam had pumped out 110bhp at 6000rpm and 107lb-ft at 4700rpm.
Again like the Escort Twin Cam, the RS1600 transmitted its power through a four-speed manual Type 3 2000 E Cortina gearbox with a hydraulic clutch and conventional differential. The same gear ratios and rear axle ratios were also carried over.
Chassis
Another feature of the Escort Twin Cam carried over to the RS1600 was the special Type 49 pressed steel bodyshell which was in turn an uprated and stiffened incarnation of the Type 48 used by the two-door 1300 GT. As per every Mk1 Escort, both variants shared a 2400mm wheelbase and rear-wheel drive layout.
The Type 49 shell came with inner wing strut towers that had small flitch plate strengtheners and a wing-rail-to-strut-top strengthener on the top of the strut tower. The front suspension top plates had a double skin spot welded in place.
In terms of the floor, the centre and rear exhaust hangers were modified. The back of the floor had axle tramp bars mounted to it. Rear spring hangers were of the skidded type. A stone deflector bolted in place underneath the boot floor.
Offset engine mounts were used that pushed the nose of the engine towards the left-hand side of the car (a hangover from the Twin Cam’s wide Lotus cylinder head with its pair of sidedraught Weber carburettors that fouled the right-hand side inner wing). For similar reasons, the brake and clutch master cylinders were mounted on the front bulkhead.
Type 49 shells also received modifications to the gearbox tunnel with the gear lever cavity moved further back and a supplementary plate welded in place.
To improve weight distribution (and because there was no longer sufficient space in the engine bay), the battery was housed in the left-hand side rear fender. Moving the battery to the trunk meant that the spare wheel now had to be bolted to the boot floor (instead of the usual upright position) which resulted in reduced luggage space than a regular Escort of the time.
Also housed in the trunk was a 9 gallon (40.9-litre) fuel tank located in the right-hand side rear fender.
Independent front suspension was via coil springs with Capri-sourced MacPherson struts and track control arms. Ford also added an anti-roll bar.
The back end employed a live axle with semi-elliptic leaf springs, radius arms and double-action telescopic dampers. The biggest change compared to the 1300 GT was the Type 49’s adoption of different radius arms which were essential to keep the beefier rear axle (sourced from the Lotus Cortina) in position.
As a consequence of the uprated suspension configuration, ride height was lower than normal.
Like the Twin Cam, the hydraulically-operated and servo-assisted brake system ran 244mm discs up front and 229mm drums at the rear.
Similarly, 5.5 x 13-inch pressed steel rims with chrome hub caps from the Lotus Cortina were used and originally shod with 175HR70 tyres.
Bodywork
Like the Twin Cam, at first glance the RS1600’s all steel body looked like any other Mk1 Escort. However, there were a handful of subtle differences.
At the front, Ford fitted a special two-piece front bumper that allowed increased airflow to the engine bay.
A black instead of natural alloy front grille was also installed and all four wheelarches were subtly flared.
Otherwise, aside from the wider than normal wheels, the only external change were RS1600 badges affixed to the boot lid and front fenders.
Initially only one colour was available: Ermine White.
Interior
Inside, the Twin Cam and RS1600 were broadly similar to the Escort 1300 GT with a couple of special items thrown in.
Behind the imitation leather-rimmed three-spoke sports steering wheel was an oval six-gauge oval binnacle with a natural alloy fascia. The two large dials (an 8000rpm rev counter and 140mph speedometer) were flanked by a cluster of four smaller read outs (fuel, oil pressure, water temperature and battery charge). The original natural aluminium dash fascia and deep-dish ‘Springalex’ steering wheel were later switched a satin black and flat RS-branded item respectively. The seat pattern was also changed in later years (as depicted above).
Upholstery was a mix of vinyl PVC and carpet. Fluted seat centres matched the door trim panels.
The windscreen washer control was a foot-operated button mounted on the floor to enable the driver to keep both hands on the steering wheel.
Standard equipment included wind-down windows, a heater / de-mister, two-speed wipers with non-lift blades, sun visors and an ashtray.
Options
Customers could upgrade their RS1600 with a number of optional extras to include a heater, a Webasto sunroof, faux wood cockpit trim, a vinyl roof, a cigar lighter and map reading light.
Performance-inspired options included Rallye Sport alloy wheels, Bilstein dampers, a limited slip differential, a roll cage, a fire proof rear bulkhead, a sump guard, a supplementary oil cooler, a battery isolator switch, flared wheelarches, wider magnesium alloy Minilite wheels and spot lights.
Weight / Performance
In standard trim, the RS1600 weighed 785kg which was the same figure that Ford had quoted for the Rwin Cam.
Top speed went from 113mph to 115mph for the Dellorto-equipped version and to 120mph if fitted with Webers.
The 0-62mph time dropped from 8.7 seconds to 8.5 and 8.4 seconds respectively.
Production Changes
The first RS1600 to roll out of Ford’s AVO plant at Aveley did so on November 2nd 1970, a little under ten months after production had started at Halewood. From this point customers could choose Sunset Red and Maize Yellow as well as the original Ermine White. Soon afterwards, Sebring Red, Daytona Yellow, Monza Blue and Electric Blue were offered and other shades became available as a special order.
In early 1971 Ford began to offer two option packs: Custom and Clubman.
The Custom Pack was created for those customers that wanted a slightly more refined vehicle than the standard offering. It came with extra sound deadening (to include floor and under bonnet), plush deep-pile black carpet, special ‘comfort contoured’ front seats, Bri-Nylon fabric upholstery, a new centre console complete with oddments tray, a map reading light and a heated rear window.
The Clubman Pack was aimed at those buyers who wanted to go rallying. It comprised four seven-inch spot lamps complete with plastic covers (two driving lights and two fog lights), uprated front springs with heavy-duty top mountings, dual gas/oil dampers, a map reading light, front bucket seats and a rollcage. At extra cost customers could also specify stone guards for the spot lights along with a magnesium alloy sump shield and off-road tyres.
During 1972 Ford introduced the AVO Special Build programme that enabled customers to choose from the full range of competition upgrades direct from the factory in order to create what they called an International Rally car, Club Rally car or Hi-Series Street car.
The list of potential upgrades was extensive. It included: a heavy duty front chassis crossmember, a heavy duty rear axle assembly, heavy duty rear axle shafts and bearings, a rear axle cooler kit, a rear axle diff protection shield, a front strut brace, thicker stabilising mounts, reinforced lower suspension arms, uprated front hubs, rear disc brakes, larger diameter brake discs with uprated calipers, alloy wheels, an uprated steel crankshaft, uprated connecting rods and main bearing caps, a dry-sump conversion kit, a magnesium alloy sump shield with mounting bar, a five-speed ZF gearbox, a magnesium alloy bellhousing for the five-speed ZF ‘box, a twin or triple-plate clutch, a steel flywheel, a wheelarch extension kit, a fibreglass hood and trunk lid, lightweight doors (a mixture of steel and aluminium), plastic side and rear windows and a competition-spec. four-gauge instrument cluster.
The most significant change to the RS1600’s specification came in October 1972 when the original cast-iron cylinder block was replaced with a purpose-built light alloy version created that enabled competition engines to be taken out to two-litres (the existing cast-iron block had a maximum capacity of 1835cc).
End of Production
Ford discontinued RS1600 production in November in 1974 having completed 1137 examples. However, significantly more than 137 were built after September 1970 (when Group 2 homologation was approved following completion of 1000 cars) which places a question mark over whether Ford had actually built the requisite number needed to go racing when they claimed to have done so.
The RS1600’s successor, the Mk2-based RS1800 was produced from March 1975.
Competition History
The RS1600 went on to have an extremely successful career in Touring car racing.
Although it picked up a brace of wins during its debut 1971 European Touring Car Championship campaign (at the Salzburgring Trophy and Jarama 4 Hours), Alfa Romeo’s 2000 GTAm was the class of the ‘71 field in and the Italian firm was crowned that year’s Manufacturers’ champion.
However, between 1972 and 1975, the RS1600 emerged as the car to beat in the Division 2 and later Division 1 category. It won five of the nine races in 1972 as Ford won the first of four consecutive ETCC titles.
Another four wins in 1973 was followed up by a historic clean sweep in 1974 when the RS1600 won every ETCC event it contested. The car delivered Ford its final ETCC Manufacturers’ crown in 1975 with four wins from six events.
Elsewhere, various domestic titles were won around Europe while in rallying, the RS1600 most notably went on to record victories on the 1972 Safari and RAC Rallies that made up the forerunner to the World Rally Championship (the International Championship for Manufacturers). The 1973 and ‘74 seasons saw Ford win the 1000 Lakes and RAC rallies two times apiece.
Text copyright: Supercar Nostalgia
Photo copyright: Ford - https://www.ford.com
