Emboldening the Spridget has become an industry.
The most prolific period for Spridget engine transplants was the 1970s. By then there was a good supply of second-hand Midgets and Sprites cheap enough for experimentation, and a far broader range of suitable engines. Fiat twin-cams were a popular choice, available cheaply from rotten or written-off 124s and 125s, and often with the added attraction of a five speed gearbox. In the USA and Australia, some Japanese engines found favour, including the twin rotor Mazda 12A. In Britain, the Ford Kent variants were the default choice, plentiful and easily fitted, with far more power than could be cheaply and reliably extracted from an A-series.
Creating these hybrids was not a task to be taken lightly, requiring mechanical knowledge, a variety of skills, a well-equipped workshop, and often an iron will and determination.
In 1971, Formula 2 racing driver David Martell saw a potential market for off-the-shelf re-engined Midgets, in part emulating Jack Brabham’s Sprite-Climax venture ten years previously, but with a different business strategy. His Bedfordshire-based company, Car Preparations built and marketed Midgets fitted with Ford crossflow engines and re-branded as the Atlantis 1600GT. Despite the unfamiliar name, the cars were distinguished from the Abingdon original only by rather egregious decals and front quarter-bumpers in place of the usual full-width items.
Only new ex-factory Midgets, bought complete, were used and they came specified with a number of options appropriate to the increased power; brake servo, 3.721:1 rear axle ratio and a 5/8 inch gauge front anti-roll bar. The cooling systems were upgraded with a larger capacity cross-flow radiator with a remote header tank, and at the rear, the stock Midget axle was more effectively located with a pair of radius arms and a Panhard rod. A modified MGB fuel tank was fitted, providing a ten gallon capacity, rather than the original’s barely adequate six.
As well as the extra engine capacity, the Ford engine had some significant advantages over the Midget’s 65bhp A-series. The crossflow cylinder head gave each valve its own port, and far more porting room than the A series, whose five ports (two inlet, three exhaust) were on the same side of the engine as the pushrods. The Ford engine was oversquare, with a crankshaft stroke almost four millimetres shorter than the A-series. That crankshaft ran in five main bearings, two more than the A-series had.
Ford did not share the BMC and Rootes fetish for twin carburettors; those used to the pestilential task of balancing pairs of SUs or Zenith-Strombergs would have welcomed Ford’s choice of a single twin-choke Weber. The Ford single-rail close ratio gearbox would have been a revelation to users of the old A35 derived transmission; synchromesh on first gear, near-silent running, and class leading shift quality.
There was an impressive thoroughness about the management and promotion of the Atlantis conversion. Installations on pre-owned cars were not offered, although part exchanges were an option. The A series engines were sold complete and as new to a trade customer, keeping down the price of a new 1600GT to £1166. For comparison, a Midget cost £970, and an MGB roadster £1308. With its 86bhp (DIN) Ford engine the Atlantis easily outperformed the MGB; Autocar recorded a top speed of 110mph and a 0-60mph figure of 10.8 seconds.
At the Atlantis launch in spring 1971, David Martell promoted the car widely to the media, with road tests published in Motor Sport, Autocar, Cars and Car Conversions, Safety Fast, and Hot Car. Reports were favourable, highlighting value for money and the beneficial change of character achieved with the Ford engine and gearbox. Hot Car described the Atlantis as “the Ford-British Leyland merger the Financial Times didn’t hear about”.
Their evaluation was more thorough than other publications, and criticised the disturbing axle tramp experienced during standing-start acceleration tests, while noting that Car Preparations were re-thinking the axle location geometry to address the problem. A half-shaft broke during Hot Car’s tenure. The tester tactfully observed that this may have resulted from six publications road testing the car, but nevertheless “Atlantis owners who modify their Ford engines may get trouble”.
Although the Atlantis received widespread and favourable media attention and was advertised in a manner reflecting the attitudes and preoccupations of the time, little is known of how many were delivered, or how long they were available. Perhaps it arrived a few years too late. The target customers’ aspirations had moved from traditional two-seaters to rally-inspired tin-tops, especially the Ford Escort Mexico which shared the Atlantis’s powertrain and cost £1219 in May 1971.
In the decades which followed, the fervour and ingenuity of Spridget engine-swappers was unabated. The portfolio of donor engines had expanded, along with the imagination and budgets of converters. Some Rover V8 conversions are said to exist, and there were further Jaguar XK installations. However, some serious four cylinder power was available by the late 1980s and into the following decade, with Toyota 4a-GE, Nissan SR20DET, Ford Sierra Cosworth and BMW S14 units appearing in Spridget engine bays.
One enterprising individual even set out to out-fright The Fright, taking a 73/74 round-arch Midget and extending the wheelbase by 100mm to accommodate a Jaguar V12 engine. Drive was taken to the rear wheels by way of a Porsche 928 transaxle. The V12’s cooling load was handled by a large radiator and cooling fans mounted in the Midget’s boot.
Motorcycle engined Midgets include several with the 1300cc Suzuki Hayabusa in-line four, and one example fitted with an 1100 cc V4 from a Honda Magna V65 custom bike.
For the less ambitious, the more suitably sized and shaped Ford Zetec 1.6-2.0, Rover K-series and Mazda B6ZE engines became widely available in the 1990s and continue to find favour.
As I write this, almost 43 years have passed since the last MG Midget left Abingdon, yet the Spridget engine transplant industry thrives. Sussex-based Barratt Engineering offer kits to fit the Nissan CG engine, with or without a five speed RM7E Suzuki gearbox. All necessary installation parts are supplied, at a cost of between £2200 and £2600. That excludes fitting, and the engines and gearboxes themselves, still readily available but likely to require overhauling before installation. Not a cheap pursuit, but the reader will have already realised that the love for these cars and the urge to perfect them transcends vulgar money or – some might think – rational judgement.
Even British Leyland could not resist the engine swapping bug. In late 1974 the Midget, got its own power unit transplant, although the sprawling conglomerate’s extensive arsenal could not provide anything as well suited to the Midget as David Martell’s chosen Ford Crossflow.
To be continued.
 According to one description, the extra inches were inserted within the bulkhead zone, with the visual giveaway of an extended external panel between the trailing edges of the front wings and the leading edge of the door opening.
 The Nissan CG “Clean Green” engine is an all-aluminium 16 valve twin cam unit mainly used in the 1992-2003 Micra. Not only is it close in size and proportions to the BMC A-series, it also has 998cc and 1275cc capacities, as well as a longer bore and stroke 1348cc version.
 The Suzuki gearbox was used in the 2001-2005 Jimny.
Reference sources: Hot Car July 1971/ Autocar May 20, 1971 /jacobsmidget.com/ midgetandspriteclub.com/ spridgetguru.com/ sebringsprite.com/ barrattengineering.co.uk