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Chapter 16 – Luxury Cars – The “S” and The “Twin-Cam SS”

by John Watson

Lotus Seven "S" (damaged)


In standard form, the Ford crossflow engine supplied with the Series Three Lotus Seven produced a mere 84bhp. This was no great shakes compared with the 120bhp rated 1500cc Cosworth pre-crossflow unit that was available as an option with the previous Seven model. Lotus were already using Suffolk specialists, Holbay, in an exclusive deal, for the engines in their Formula Ford models, and it was this company that modified the 1600cc Ford engine fitted in the Seven to produce 120bhp at 6,200rpm. Dubbed the ‘CFR’ it was specially balanced unit having, a gas-flowed cylinder head, a pair of Weber 40DCOE2 sidedraught carburettors, R120 high lift camshaft, special pistons and a 10.0:1 compression ratio.


An ‘Ultimate Seven’ car was made for the Racing Car Show of January 1970. Chassis # SB2402 had a fully painted livery of Rolls Royce Regal Red metallic and boasted luxury trim previously unknown in a Seven, consisting of better padded and contoured seating, interior trim panels and weather equipment all in an ivory colour, as well as a brushed aluminium finish to the dashboard. Also included were seat belts, heater and GKN manufactured Dunlop cast alloy wheels shod with Dunlop SP41 tyres as standard and even, for the first time, a push-button radio (Pye Major) hung to the right of the steering column with a speaker mounted in the boot. It was planned to produce a number of cars with this specification, but at £1600 on the road there were no takers and in the event only one was made.

Lotus Seven "S" dashboard

Lotus Seven "S" interior (with Radio!)


Following the show, the car was registered for the road TNG7G and tested by several magazines including Car, Hot Car, Autocar, Motor, Car & Car Conversions and Motorsport. According to these tests, several gear ratios were employed. Car magazine’s figures for the vehicle were: Top speed 108mph, O to 60mph 7.4 seconds and a thirsty fuel consumption of 18.4mpg.


TNG7G, the Lotus Seven ‘S’ remained with the factory for 18 months before being sold on. Over the intervening years it has had at least 8 owners before arriving with it’s current owner in Hampshire in 1985. Currently undergoing a ground-up restoration, it will soon be seen on the road in it’s original glorious state.


Whilst an obvious development of the Seven was to install Lotuses own twin-cam engine from their Elan and Cortina models; the factories official line was that this was not possible, as the unit would not physically fit in the Seven’s engine bay. Strangely despite this official line, the factory records clearly show that some years earlier, in March 1965, a Cosworth twin-cam engine was supplied by the factory in a Seven bound for Australian Lotus dealer and racer, Leo Geoghegan. As ever with the Seven, modifications and improvements went on both within and outside the confines of the factory and by the middle of 1969 already the ‘impossible’ had been accomplished. Despite this, Lotus stuck to their guns and it was only when Graham Nearn of Caterham Cars Sales arrived at Hethel in a customers twin-cam powered Seven that the factory finally conceded that it could be done.

Lotus wheel catalogue


With the Motor Show just weeks away, Lotus Components set about producing a twin-cam powered Seven for their stand. Whilst by using their own in-house produced engines, there were cost savings, there were also some badly needed structural chassis modifications as well. The Series Two had originally been designed around engines producing less than 50bhp. Now with nearly treble this power, some racing owners using sticky tyres were experiencing broken chassis tubes etc. If Lotus were to offer a more powerful model to the public, these issues had to be addressed or there would be future problems. To increase chassis strength, triangulation was added both around the bottom of the engine bay and to the chassis sides. In addition steel side panels were welded directly to the frame which was to become a feature of the future Series Four model.

Lotus Seven "SS" at the Earls Court Motor Show


There was no time to get the car running for the show, infact work carried on right through the night before just to get it ready as a static display. With its ivory white paintjob and special GKN Brand Lotus cast alloy wheels, it really did ‘cut a dash’ on the stand. Called the ‘SS’ (standing for Super Seven) but also hinting at the romance of the pre-war Jaguar SS cars, the car’s powerhouse was a special Holbay tuned version of the Lotus twin-cam engine rated at 126bhp at 6,200rpm.


During the show Graham Nearn took enough deposits against the kit form price tag of £1,225 for another dozen cars to be made. The chassis frames for the production versions did not have the steel side panels, but just the added triangulated members. These frames were given the reference SS80 and were coated in black as opposed to the traditional grey.

Lotus Seven "SS", rear view


Special features of the twin-cam SS include: Body colour to customer’s choice, GKN manufactured 13” x 5½J Dunlop or sometimes Brand Lotus cast alloy wheels shod with Dunlop SP41 tyres, Lower mounted front indicators, Semi flush rear lamp clusters, Improved contour padded seating in grey PVC, Interior trim panels and weather equipment in matching grey colour, Additional trim to scuttle top, Brushed aluminium finish and engraving to the dashboard, Seat belts, Twin-cam engine with Lotus Holbay cam cover labelling, 3.77:1 limited differential ratio, Heater, Maserati twin tone air horns,


According to the Lotus records there were just 13 Twin-cam SS cars made by the factory. With the chassis # prefix ‘SC’ and suffixes ‘TC1 to 13’ they were not given consecutive numbering, but they all left Lotus by the end of January 1970. Just one was left hand drive, but there were clearance problems between the steering column and the dynamo so a Holbay Clubmans crossflow engine had to be fitted instead of the twin-cam unit. Of the 13, one went to Iran, three to the USA, one to Germany, one to Scotland and one to Spain; the remainder being sold to customers in England.

Lotus Seven Twin-Cam “S” – engine detail

Twin Cam engine detail


Of these rare and highly desirable cars, three are known to be in the UK in nicely restored condition, one is reportedly in Germany, four are in the US or Japan and one is presumably still in Iran where it was originally sold to; leaving just four whose whereabouts is unknown. In addition to the left hand drive car, one other has since had a crossflow engine fitted.

(Article first published in July 2005)

Sources and further reading:

Lotus Seven by Jeremy Coulter (1986/1995)

Lotus Seven Preparation/Restoration/Maintenance by Tony Weale (1991)

Pictures by kind permission of Ferret Photographic.



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