MGA Twin Cam: on track in an ex-works racer

By Simon Hucknall

| 4 Jun 2024

Classic & Sports Car – MGA Twin Cam: on track in an ex-works racer

There are two reasons for feeling guilty today.

First, the MGA Twin Cam into which I’ve just squeezed myself is almost unchanged from the day in March 1960 when Jack Flaherty and Jim Parkinson took the chequered flag in it at the 12 Hours of Sebring, finishing fourth in class.

Its paint, roundels, mechanicals and even the wonderfully patinated competition seat on which I’m sitting are all virtually as they were when the car left MG’s Abingdon works 64 years ago.

The MGA Twin Cam’s worn bodywork tells the story of this unrestored racer

Driving it the 50 miles to our destination in truly biblical weather feels like sacrilege.

Then there’s the car’s mileage, sitting at just under 6400.

That’s an average of 100 miles a year since it was built, so accruing that in one day seems almost profligate.

But this works MG racer wasn’t built to be mollycoddled.

UMO 93 has covered fewer than 6400 miles from new, but has spent many of those in the heat of competition, as its maker intended

In fact, even the production Twin Cam on which it was based, launched in 1958, was intended for ‘competition-minded motorists’, according to Autocar.

It looked identical to the standard Syd Enever-designed MGA, which had arrived three years earlier, but significant upgrades were introduced to make the model competitive for amateur racers in 1300-1600cc production classes.

The B-series engine was bored out from 73mm to 75.4mm, increasing displacement from 1489 to 1588cc (the regular MGA followed suit a year later).

The engine bay patina reveals this MGA Twin Cam’s original Ash Green paint

Dunlop disc brakes were standard all round, as were Dunlop peg-drive, knock-off steel wheels.

But the headline change was the introduction of an aluminium double-overhead-camshaft cylinder head, replacing the standard car’s iron head, overhead valves and single camshaft.

MG first experimented with the twin-cam set-up in a B-series-engined prototype at the Dundrod TT in 1955; twin-cam streamliners EX179 and EX181 (the latter supercharged) went on to break class speed records in 1956 and ’57 respectively.

The MGA Twin Cam got a double-overhead-camshaft cylinder head, a raised compression ratio and a capacity boost from 1489 to 1588cc, lifting power in road trim to 108bhp

For the production car, other than new conrods and domed pistons (raising compression to 9.9:1), the B-series’ bottom end remained largely unchanged.

The revised engine weighed 50lb more, but the new head and increased capacity boosted power by 58% to 108bhp at 6700rpm and increased torque by 35% to 104lb ft at 4500rpm.

Magazine test performance figures varied, but Autocar recorded 0-60mph in 13.3 secs, 1.7 secs faster than the cooking MGA.

‘The painted roundels look original, and the MG now wears the number 40 it once sported at Sebring all those years ago’

By the time its testers hit 90mph, however, the Twin Cam was 15 secs quicker – as well as posting a maximum of 114mph, 14mph up on the regular model.

Which was all very eye-catching, but if MG wanted to find the right buyers, it needed to put its money where its mouth was – meaning competition.

With more than 80% of MGA buyers based in the USA, entry in high-profile Stateside races was a given.

This MGA Twin Cam’s roof light helped to identify UMO 93 during night stints

Abingdon already had form here: since Briggs Cunningham had established the Sebring International Raceway in Florida, MG had supplied cars for its 12-hour endurance races between 1951 and ’56, run by the company’s US importer and achieving a string of solid results.

In 1959, Abingdon prepared three works cars for Sebring’s 12 Hour Grand Prix and delivered them to US concessionaire Hambro Corporation.

All three finished a rain-soaked race, two of them second and third in the 1300-1600cc class.

The start of the 1960 Sebring 12 Hours, with one of the works MGA Twin Cams on the left © barcboys.com

The pressure was on to do more the following year.

In early 1960, six Ash Green Twin Cams rolled off the line and were passed to BMC’s Competition Department.

Mechanically they remained largely standard, although the engines were blueprinted and received larger 2in SU carburettors, versus the standard 1¾in items, with an extra front air feed from a vent to the right of the grille.

A modified oil filler with a pushrod half-turn cap was fitted, and an extra bonnet vent ducted cool air into the cabin.

UMO 93 at speed during the 12-hour race at Sebring © barcboys.com

The MGA’s standard four-speed ’box gained a closer set of ratios, sending power to the rear wheels through a limited-slip diff.

And, to comply with the new touring-car regulations, part of the MGA’s rear cockpit was cut away and a glassfibre panel fitted for a (theoretical) overnight case.

A long-distance, 20-gallon fuel tank meant the boot floor had to be chopped, while the filler was moved up the body for easier access.

The chassis remained stock Twin Cam, with a small modification so over-centre jacks could be used in the pits.

‘The MGA Twin Cam racers remained largely standard, but the blueprinted engines had larger carburettors, with an extra front air feed’

Finally, both bumpers were removed and a lightweight Vanden Plas aluminium hardtop was added.

All cars were repainted in British Racing Green.

Of the six Twin Cams Abingdon sent to its UK agent Crowthorne Motors for onward shipping on 16 February 1960, four were destined for Sebring, with one remaining in the UK and another being sent to a customer in Canada.

Crowthorne – like Abingdon at the dawn of the ’60s – is in Berkshire, which explains their registration marks: UMO 93, UMO 94, UMO 95 and UMO 96 are all Berkshire numbers.

The MG plate under UMO 93’s bonnet

On arrival at Sebring, UMO 94 was allocated to all three teams as a ‘practice car’ for the Friday and adopted a ‘P’ on its roundels.

The two-driver teams were truly international, with US, Canadian and British pairings.

Lancastrian Edward (Ted) Lund drove with Colin Escott in UMO 95, the number 38 car – their second Twin Cam outing, after taking class honours at Le Mans the previous year.

This patinated MGA Twin Cam is a rare survivor

Number 39, UMO 96, was driven by Canadians Ed Leavens and Fred Hayes.

And ‘our’ car, UMO 93, wearing number 40, was raced by Americans Jim Parkinson and Jack Flaherty, the latter a West Coast sprint-car champion and Reno Air Races ace.

At 10am on Saturday 26 March, an audience of 50,000 watched the flag drop on the 12 Hours of Sebring, round two of 1960’s FIA World Sportscar Championship.

The MGA Twin Cam’s small gearlever is within easy reach of its large steering wheel

Of the 72 cars that qualified, Stirling Moss and Dan Gurney in a Maserati T61 ‘Birdcage’ had been the main attraction, although an engine failure put paid to their campaign before the race began.

The starting grid was organised according to engine size, rather than qualifying times, putting the British Motor Corporation-entered MGAs near the back in the Grand Touring 1600 class.

Alas, BMC’s Brit contingent lasted for only three of Sebring’s 5.2-mile laps before UMO 95 developed a top-end engine fault (either valve-spring or camshaft failure), bringing a DNF.

This MGA Twin Cam’s rev counter is redlined at 6000rpm

But Twin Cams UMO 96 and UMO 93 soldiered on to the end, finishing a creditable 24th (third in class) and 29th (fourth in class) respectively, with Hans Herrmann and Olivier Gendebien’s Porsche 718 RS60 victorious overall.

‘Our’ car crossed the line after 148 laps, just three tours behind the Tony O’Sullivan-entered AC Ace in the class above the MGA, proving – in race conditions, anyway – that the Twin Cam punched above its weight while remaining durable over a near-800-mile distance.

Unfortunately, around the time of the race, local Twin Cam owners were experiencing reliability issues.

The MGA Twin Cam racer has comfortable seats

Many were using the cars for touring, not recognising that the model’s more highly strung motor was intended for race use, with a commensurate up-step in maintenance required to retain its durability.

As a result, soon after the race, all production MGA Twin Cams were downgraded from 108bhp to 100bhp, with a reduced compression ratio to prevent the detonation that had occurred in many customer cars’ engines.

Thankfully, UMO 93 – chassis YD2/2571 – retains its full-fat factory output, although its original cylinder head has had some fettling since Sebring.

UMO 93’s sturdy rollbar is one of the few changes from a roadgoing MGA

Immediately post-race, its sister cars were returned to concessionaire Hambro in upstate New York and sold on in the Buffalo area, but ‘our’ car went to Ship & Shore Motors of West Palm Beach, Florida, before being sold to racer and collector Dr Paul Buchanan of Charleston, South Carolina.

Buchanan raced the Twin Cam until the motor dropped two valves at Daytona in 1963.

The car was then put into storage before being sold on 17 June 1967 to Lyle York of Anderson, Indiana, for $600.

‘The body-on-frame jitteriness apparent on scarred roads is gone, and this MGA Twin Cam feels composed, neutral and grippy’

Subsequent correspondence between York and Buchanan reveals ongoing debate about the engine’s maximum revs, with Buchanan noting: ‘Redline was 7200rpm as calculated from piston speeds.

‘I not infrequently went to 7500 in third. These readings are for the Isky [racing] cams.

‘For the standard grind, lower the above figures to stay with the power curve. Suggest 6500.’

With the valves and head repaired, York continued to use the car until the clutch failed in 1970, still with just 5139 miles showing.

UMO 93 heading to a fourth-in-class finish at Sebring

For the following 33 years the MG sat on blocks in dry storage, before being sold once again, then finally returning to the UK in 2017, since when it has been displayed at the Concours of Elegance at Hampton Court.

Today, UMO 93 looks as if it has a story to tell.

The original paintwork is scattered with battle scars – none too severe – from its competition life.

But in other places, such as on the engine bay bulkhead, specks of Ash Green are emerging from chipped areas of BRG, revealing the original production colour.

Lucas spots poke from either side of the grille, with the single intake for the SUs positioned just behind the offside light.

The painted roundels look original, and the MG now wears the number 40 it once sported at Sebring all those years ago.

The telltale roof light, helping the team quickly identify which Twin Cam was flashing by in the dark, remains in the centre of the hardtop; up front, a battery kill switch, bonnet scoop and leather tie-down strap all mark out UMO 93 as the dyed-in-the-wool racer it once was.

There’s a gaping vent alongside the MGA Twin Cam’s grille, which feeds its larger 2in SU carburettors

All of which puts you in the right frame of mind as you enter UMO’s cabin.

Racing seats – actually, rather plump and comfortable roll-top leather chairs rather than buttock-pinching buckets – and some pull-out knobs for the additional lighting are the most obvious differences.

Then you glance in the dash-mounted rear-view mirror and see a chunky rollover bar framing the back window.

Before you is the standard Twin Cam’s large, thin-rimmed four-spoke steering wheel, behind which are a rev counter (redlined at 6000rpm, just shy of Buchanan’s suggestion), a 120mph speedo, and secondary fuel and combined oil-pressure/water-temperature gauges.

The MGA Twin Cam’s revamped B-series engine was durable if well maintained

Even with the seat in its rearmost position you sit close to the Twin Cam’s wheel, with the fingers of your left hand able to form a bridge between its lower rim and the top of the gearlever.

The pedals are nicely spaced, and after you’ve flicked down the fuel-pump switch and thumbed the starter, pulling away is an untemperamental process.

First gear is tall, but second and third are very close, with a larger gap to top, which still runs at around 19mph per 1000rpm; even a 6500rpm limit (Flaherty and Parkinson were pushing above 7000, by all accounts) would allow 123mph down Sebring’s straights.

This time-capsule MGA Twin Cam is the perfect antidote to restomod racers

The MGA’s rack-and-pinion steering is a delight: not overly weighty at low speeds, but full of feel, devoid of play off-centre and quite direct, with 2.75 turns from lock to lock.

This, combined with the precise and narrow throw of the little gearlever, renders the Twin Cam tactile and engaging from the off.

Our destination today is a rainswept Castle Combe Circuit, where we hope to enjoy an essence of what Flaherty and Parkinson experienced back in the day.

This MGA Twin Cam racer embraces its imperfections

Accelerating down Avon Rise towards the notorious Quarry right-hander, the B-series engine is no aural sophisticate: plenty of noise from the valvegear is amplified in the cabin by the aluminium hardtop.

But step beyond 4000rpm – easy to do with such a responsive throttle – and a distinct twin-cam snarl takes hold, beckoning you closer to the redline out of each bend.

Any hint of the body-on-frame jitteriness that had been apparent on the scarred roads around Castle Combe is gone, and UMO feels composed, neutral and grippy as you push a little harder.

From Sebring to Wiltshire, this MGA Twin Cam still turns heads

The Dunlop discs need plenty of pedal effort from higher speeds, but, once acclimatised, they are strong and reassuring, and you can imagine how easy it would have been for UMO’s drivers to outbrake heavier and more powerful machinery into tighter corners.

This diminutive racer is a jewel. But what makes UMO 93 so captivating is its authenticity.

At a time when so many period circuit cars have been fettled way beyond their original abilities, this MGA Twin Cam has remained faithful to its roots – and is all the better for it.

Images: Jayson Fong

Thanks to: Will Stone Historic Cars; Castle Combe Circuit

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