Which classics still have the potential to get up and go? Paul Davies remembers the cars, the people… and how to make a classic hot car!

In the good old days, when Elvis was still alive, you were either on one side or the other when it came to cheap sports cars. It was war, only this time the Spitfires weren’t flying overhead – though the enemy craft still began with an ‘M’!

Those who piloted MG Midgets or Austin Healey Sprites firmly believed their nimble little number was best, but the Triumph Spitfire boys just knew they were winning the battle for Britain’s roads. It was blokes with stringback gloves versus hairdressers with fl are trousers (angry emails to Mr Davies, not us-ed). Early Spridget owners could aim fi re at the namby-pamby wind-up windows, the uncertain behaviour of the swing axle rear suspension, and the slightly feminine image of the Spitfi re, and laugh. No battle about it really, the Spridget was the real man’s car, with a motorsport heritage stretching back to pre-war days.

In fact, from my own experience, there was even more of a war going on: most of the time, Sprite drivers didn’t speak to Midget drivers either! Born in 1958, with a little help from Donald Healey, Austin’s little sports car matched a cheeky body with a twin carburettor version of the BMC A-Series engine of the A35 saloon. Packing just 43 brake horsepower, the Austin-Healey Sprite was in the tradition of MG’s pre-war two-seaters – relying on its light weight and nimble handling above sheer grunt.

The formula was dead simple, and remained so through nearly two decades. Front engine – which grew from 948cc through 1098cc to 1275cc – and four-speed, three-synchro, gearbox, driving to a live rear axle. Front suspension (like the A35) was wishbones and coils, while the rear consisted of quarter elliptical leaf springs. Disc brakes you got only at the front, post ‘62. One of the best aspects, right from the start, was the car’s super-precise rack-and-pinion steering, derived from the Morris Minor.

When Farina re-styled the Sprite for 1961, the MG Midget clone joined the line-up and the two ran side-by-side for 13 years. USA crash and emission regulations effectively killed the ‘real’ car off in 1974, when, for the rest of the production run, all you could buy was an asthmatic MG with rubber bumpers, massive ground clearance, and (whisper it) a Triumph Spitfire engine. The war had been won, and the result was – topically – a coalition.

The Sprite and Midget were the fun cars of choice for the motor clubman. Cheap to buy and a joy to drive, they could be raced or autotested (they called them driving tests then), autocrossed, sprinted or even used for hillclimbing events. Rallying was OK on smooth roads but, on the rough, the cars’ ground clearance was a bit of a problem.

The key to all this excitement was that the A-Series motor was eminently tuneable. BMC went a long way to help, with parts and advice from its own Special Tuning department.

Get One Now

No problem finding a Spridget – just check the ads in Classic Cars for Sale! Frog-eye (Mk 1) Sprites will command the most money (over £10k is common) but look out for fakes with fi breglass bonnets. Of the later cars, the pre-wind-up window 1100’s are a good buy if you want originality; the wind-ups don’t look so good but have locking doors and (mainly) the 1275 engine. Pay £3k-£5 for good ones and more for top ones. The Spitfi re-engined rubber bumper models are not the best to drive, but offer strong value, starting from £2000 for a half decent example. On all models, beware of rust, especially at rear spring hangers, the sills and door pillars.

Hotting One Up

An all-iron block, with a three-bearing crankshaft, single camshaft, and a cylinder head with two inlet and three exhaust ports, doesn’t make for exciting reading. But, the head has a good combustion chamber shape, and later motors are tough. Early cars came with twin 1 1/8ins SU carbs, later with much more tuneable 1 1/4’s. As always, the bigger the capacity, the more power you’ll get, but BMC didn’t make it easy, often altering both stroke and bore to get the required fi gure. Hence, you can’t easily change a 948 to a 1098, or even to a 1275. Check the numbers on the plate on the top of the block. The first numbers and letters are the most important:

9CG: 948cc (62.9mm x 76.2mm) – 43bhp.
10CG: early 1098cc with 1.75ins. diameter mains bearings (64.5mm x 83.7mm) – 55bhp.
10CC: later 1098cc with 2.0ins. diameter mains bearings (64.5mm x 83.7mm) – 58bhp.
12CC: 1275cc (70.6mm x 81.2mm) – 65bhp. (Based on the Cooper S but without some of the expensive bits. Identified by the absence of plates on the block side that, on other engines, allows access to the cam followers).

Both the 948 and 1098 engines remain severely limited by their crankshaft and connecting rods – especially as they are likely to be 40-plus years old by now – so you should consider 80bhp and 6500 rpm to be the top fi gures for these. The best of this bunch is the 1098 engine, with larger main bearings, which made its debut in the last year of the Mk 11 Sprite and went on to power the fi rst of the wind-up window models.

After this, 1275cc is the way to go. The bigger capacity means ultimate power output will be greater, and it’s got a bigger bore and shorter stroke so it will rev better. A plus-0.020ins bore takes the 1275 motor to 1293cc, which just ducks under the 1300 motorsport class limit.

With no class restrictions to consider, the block will take a bore of 73.5mm which, with a stroke of 81.3mm, means an overall capacity of 1380cc. Beyond this, things start to get (very) expensive.

It is possible to offset-grind the Marina 1275 crank journals to take 1275 Cooper S connecting rods (which results in a stroke of 84mm) and, with the block offset bored (to line up with the crank) to 73.5mm, the end result is a lusty 1425cc.

Early versions of the Weslake designed cylinder head will take quite a bit of tweaking – higher compression ratio, bigger valves, re-shape chamber and enlarged ports. Whilst the Spridget 1275 head came with 33.4mm inlet and 30.8mm exhaust valves, best for tweaking is a nine-stud one from a 1275 Marina (12G940 casting number). The standard (35.6mm inlet/30.8mm exhaust) valves work pretty well.

Just for interest, Special Tuning made a big valve head with 1.48 (37.6mm) inlets, and the ultimate was an eight-port, cross fl ow, alloy job that was usually matched with a pair of big SUs or four Amal motor cycle carbs. The Marina head responds well to gas fl owing, and the ports should be matched to the inlet manifold, but there’s not much scope for improvement in the combustion chamber itself. However, a, free fl ow, long centre branch exhaust manifold is essential.

Where extra power comes is in the carburation – twin 1 1/2ins SUs are a good bet on the twin inlet port head, otherwise a single Weber 45 DCOE – and a change of camshaft. BMC’s own competition 544 (Formula Junior) profi le was good for fast road use and the 648 (Race) for competition.

Both Piper (http://www.pipercams.co.uk) and Kent (http://www.kentcams.com) can supply model equivalents.

With modified 1275 head, fast road cam, etc, expect around 100bhp. A more modern approach is to consider adapting the Metro turbo installation (has been done) or fit a later K-Series engine.

Kits are available from Frontline Spridget.

Handling The Power

Front suspension and steering is pretty good. Uprated coil springs and larger diameter antiroll bar are worthy plus you can either go for stiffer lever-arm dampers or – preferably – convert to telescopics, such as Spax. Kits for this are widely available. Some specialists recommend more negative camber to lessen understeer and quicken steering, although the Spridget is quite agile and darty as it is.

At the rear, the quarter-elliptic springs are not ideal but, again, you can convert to telescopics to help matters. MGB Hive (http://www.mgbhive.co.uk) can supply parts. The axle ‘s location does present problems for any well-modded car. Radius arms to the axle will help damp the tramp. Plus, there are numerous kits to keep the rear axle in check with special bracing (Rear Traction Control Link, Panhard rod, anti-tramp bars, etc). Jack Knight Developments (http://www.jackknight.co.uk) can supply heavy-duty half shafts. JKD can also supply closeratio, competition gears and limited slip differentials – both essential for serious sport.

The standard ‘box is a sturdy, if vocal, affair that always lacked overdrive like the cursed Spitfi re!. The modern trick is to fi t the Type 9 Ford ‘box as found on Sierras, which not only gives you that added cog for bearable higher speed work but the intermediates also work a lot better, too.

Again, Frontline Spridget (http://www.frontline developments.com) can provide all the necessary.

Finally, don’t go mad on the wheels. Works racers often ran with Minilites but we reckon that 5 1/2ins are about right – over-tyreing will make the steering heavy, spoil the handling and put too much stress on the suspension. Oh – and do improve the brakes while you’re there!