Mighty Midget

Just a few days after last month’s Motor Sport pages went to press I was pleasantly proved a liar. For in that issue I had noted that “in general, the traditional art of making two-seaters move that little bit faster has died out”, following this uncertain ruling up with the declaration that a modified 1275 Sprite, or Midget, call it what you will, had never passed through my hands. British Leyland Special Tuning personnel were the people responsible for this month’s about face, laying on a day of modified motoring which included four sporting two-seaters among a batch of entertaining machinery. You can read about that enthralling exercise in “Performance News”, for here we want to concentrate on the outcome of that day, which for us was one hot week with one exceedingly “hot” MG Midget. After all there are not many steel-bodied, 1,300-c.c. cars which will exceed 110 m.p.h., record 0-60-m.p.h. runs in the low nine-second bracket and average 29.1 m.p.g. under irksome conditions.

However, the introductory words above should not be taken to mean this Special Tuning Midget is a perfect form of transport for even the most ardent enthusiasts among you, for there were snags – nearly all of which arose from the lack of preparation time, in turn prompted by our eagerness to borrow the car. Activities which can be classified as enjoyable have a tendency towards being either illegal, immoral or fattening, according to the proverb, and this Midget is nearly always in the first category when travelling at its normal pace on British roads, and possibly is slightly imbued with the second quality too as anything which gives such illicit pleasure must surely be!

Before looking at these pleasures in more detail let us first look at what Abingdon’s resourceful works did to concoct such a potent little brew. The engine and ancillaries are the major story in this case because in the scramble to prepare the car chassis mods were left aside. Excepting the installation of fade-resistant, Ferodo DS11 grade, disc brake pads at the front, there are no modifications apart from power unit ones. In essence the engine is a full race example of the venerable “A” series, enlarged from 1,275 c.c. to 1,293 c.c. by means of a 20-thou. cylinder rebore (so I still have not tried a modified 1275 – J.W.).

From the top BL modifications consist of a full race 11-stud cylinder head along well proven Mini-Cooper S-type lines; this head is just one stage short of the ultimate in siamese port layout at £65, whereas the big (1.406 in.) valve head is another £10. The valve train features a number of strengthened items, as well as lightened tappets, which allows the regular use of 7,500 r.p.m. for as long as the noise is appreciated, with an absolute limit recommended at 7,800 r.p.m. The standard pistons are dished, keeping the compression down below 9 to 1, but were replaced by flat-top forged pistons giving a ratio of 11.5 to 1 within those enlarged bores.

The standard connecting rods appear to be exceptionally robust items and are not changed for racing use. The crankshaft story is slightly involved because twice during the 20,000 plus Mk. 4 “Spridget” (i.e., both badge derivatives) production run there had been a nitrided crankshaft installed as standard. Unfortunately this is not the case at present, so this £30 treated shaft was necessary on “our” current production example. As one would expect on a “works” sort of motor car the reciprocating parts which have to endure all those crankshaft revolutions are carefully balanced in a highly successful attempt to eliminate vibration anywhere throughout the usable power band. Among the sundry engine changes one also finds a larger capacity sump and revised pump pick-up, a modified distributor with vacuum advance disconnected, and a 16s. dynamo pulley which has a smaller diameter to stop the risk of the electrical system over-revving itself.

Deeper breathing for the unit comes from a pair of 1 1/2-in. choke HS4 SU carburetters (standard have 1 1/4-in. chokes) partially masked by glass-fibre inlet trumpets, a suitably re-shaped standard inlet manifold is used together with a very effective extractor exhaust system. The latter emphasises the effect of the racing camshaft profile utilised on the test car so that at certain r.p.m. one gets a smooth power bonus. The camshaft is coded C-AEG 595 which seems an insignificant detail, but remember that the oil-pump drive was changed for the 1275-powered versions so this is the current coding for the old 648 or 649 cam: the legendary device which has featured in so many successful ELMC racing engines, and lined a few sharp boys’ pockets with different manufacturer’s labels attached!

The result of all this engine work is to raise maximum power from 65 production brake horsepower at 6,000 r.p.m. to a roistering 95-97 b.h.p. at 7,500 r.p.m. In other words the output is not doubled but the 13.4-cwt. car gains an extra 30 b.h.p., to sharply boost the power-to-weight ratio to the point where it is better than that boasted by a production Lotus Seven. Of course one can buy a 120-b.h.p. Holbay unit for the Seven, but that is another story.

In order to judge this Midget against some sort of known quantity we took along a Lotus Seven S4 on the collection trip to Abingdon-on-Thames. We found the Midget as we have described it, plus a pair of headlamp cowls. A seemingly pointless item for the headlamp units suffer through a scattering effect on main beam and not even supreme optimists could claim the aerodynamics were significantly improved. SOK 94H, the Midget’s registration number, struck a chord in the author’s mind for, just two weeks previously, he had reluctantly (it was sunny!) handed back SOK 95H, another of the current Midgets which have adjustable seat backs and mock leather-rim steering wheels as standard equipment. 95H had the latest 4.5-in. rim sports steel wheels, whereas the modified Midget’s Pirelli Cinturato tyres rested on 4-in. rim width wire wheels. Latest Sprites and Midgets also suffer, in my opinion anyway, from an overdose of matt black paint, but the interior changes do improve the driving position considerably – although those over six foot are still unlikely to feel at home in the car because all seat adjustment is limited by the steel carpeted shelf behind them.

The Midget set off from Abingdon with the tonneau cover on and hood down. In the week that followed the hood lay undisturbed and only once did we have to bail out a soggy interior. There is a way of travelling from Abingdon to Henley almost entirely on country roads and this we elected to do, the two open cars being at their most enjoyable over this terrain. With a standard 3.9-to-1 final drive and a considerably extended r.p.m. range the Midget proved to be at home winding up through the gears, holding 2nd gear up to an easy 60 and 3rd up to over 80 m.p.h. Frequently the Lotus Seven pilot would look down at his gear-change in a vain attempt to find a corresponding 5th gear as the Midget accelerated away at 90, keeping up a respectable urge forward until the speedometer needle fell off the clock at 100 and the r.p.m. needle indicated 6,000 plus. A very happy cruising pace is an honest 80-85 m.p.h. with the throttle eased back. The Midget pilot had his problems though: first the tachometer was standard, reading 7,000 r.p.m., stopping abruptly at this point, and secondly the brakes and road-holding were nowhere in the same league as the super smooth and thrustful engine. To solve the first dilemma we hung on for the count of two after 7,000 r.p.m. were indicated, or simply waited for the speedometer needle to indicate two or three m.p.h. more: so far as we know the car is still giving reliable service! The second problem was a lot more fun to solve, for the Midget is one of those delightful machines that can be tossed around by even a moderate driver and still return to base unscathed. Our cornering style was to brake and change down rather earlier than one would normally, then let the engine wail away happily to push the Midget round. The back wheels can be slid out to fantastic attitudes in safety, but for public road work only the very slightest of steering corrections should ever be necessary, though one can save a little steering effort by merely applying power to turn out of a side road – leaving the rear wheels to look after the navigation.

Younger people who drive a Midget in this stage of tune will probably enjoy the same love-hate relationship with the gearbox as we did. When the non-synchromesh 1st gear goes in correctly at 25-30 m.p.h. there is immense satisfaction, but if those teeth clash, what a sadistic idiot one feels! A good blip of the throttle is an essential part of the double de-clutching routine, but even though this helps I would honestly rather have all straight-cut gear teeth and no synchronisers, or a synchromesh box to the standards offered by Ford and Fiat. Apart from this 1st gear routine, the change is excellent from the stubby lever and a competition clutch does its job superbly as one feeds in 3.000 r.p.m. plus as part of the normal getaway routine.

There is a full range of modifications to improve both handling and braking at Abingdon, but as explained we were left practically bereft in both these departments – only stopping giving us any anxious moments. The lesson is obvious, even for brisk road use the braking should be improved before the converted Sprite is used. It sounds all so obvious, but the exhilaration of new found power can lead normally safe drivers into trouble if the brakes are not up to par. This was demonstrated for me when the Midget simply could not draw back from a high-speed overtaking manoeuvre while the Lotus did, and all so easily.

The Midget was used for all our normal routine traffic work and ran steadily throughout with the water temperature needle occasionally crawling as high as the N for normal mark. Oil pressure never dropped below 40 lb. per sq. in., but was a little worrying at anything over a consistent 5,500 in 4th (90-95 m.p.h.) when it would drop back from 60 to 45lb. per sq. in. – and no less. We could detect no surge during hard cornering (nicknamed “Advanced Aerobatics” by a pilot friend who drove with us!) but were nevertheless disappointed that oil pressure was not maintained to a more reassuring level with the sump definitely full. Flexibility for traffic work depends on the driver feather-footing until 3,000 r.p.m., the bulk of the engine’s power output coming in at 4,500, which feels like 2,000 revs on a standard Sprite anyway.

Altogether a fabulous little car for blowing away the dullness of everyday life at a reasonable price. The engine modification parts cost in the region of £200, an Austin Healey Sprite is just over £800, so the final cost will be in the £1,100-£1,200 bracket, depending on who does the engine assembly and how much more one wants to do in the handling department. What is far more practical and likely is that a large number of Spridget owners will fit all or some (I would suggest a less energetic camshaft for most uses) of the parts we have discussed and will derive even more enjoyment from these likeable open sports cars. – J. W.