The 750 MC racing revival

In which we talk to a cross-section of those involved in the now expanding World of 750 and 1300 Formula racing, including 1975 750F Champion, Kim Perry. We also drove the 750 Champion’s Newman DNC Mk. 3-based car, and the superbly balanced 1300F Messer 2A, constructed by Keith Messer and Jim Ravenscroft.

All racing formulae, seem to have periods where they become the thing to do in order to succeed in a driving career. However there is one category in British Club racing that has always been the carefully guarded backwater of the designer/constructor/driver character: the more successful you are at blending those three differing skills, the more you should achieve.

Even backwaters are ruffled by the waves of passing launches though, and the 750 people have never been short of controversy, since the best known examples of Mr. Chapman’s ingenuity were pined against the rule book and his fellow competitors. Today there are plenty Of heated discussions over the merits of the so-called kit cars which, in reality, are often like the bare DNC space frame chassis that requires a great deal of ingenious interpretation to successfully translate Mr. David Newman’s design into a track winner.

There are also two schools of thought on the question of sponsorship, although the traditional ban on commercial (i.e. all those who do not supply equipment or the car) advertising is certain to remain, if the 750 Club are to retain their proud motto, “leaders in low cost motor sport”.

The Club is Much more than the organising body for two racing categories though, for it includes Sporting Trials. Austin 7 Rallies at Beaulieu, and Donington. If they can find a 1976 venue and date, there’s the 6-Hour Relay to organise, and the poor Formula Four orphan Single-Seater class, which also falls beneath 750 MC. Little wonder then that the Club had to appoint one of its keenest supporters into the full-time professional task of Club Secretary and Press liaison man.

It was thanks to the excellent liaison work of Mr. David Bradley that we were able to assemble the cars, and talk to their owner-drivers at our Surrey test track. wind) was in true Lawrence of Arabia dust-storm Mood. For those interested, further details of the Club’s activities are available from Mr. Bradley at 16, Woodstock Road, Witney, Oxon (Tel.: Witney 2285).

Last season saw the 750F’s basking in the limelight with 86 competitors listed in the Club’s annual Championship points table, many of them attracted by the very low costs often quoted for this type of simple racing. Indeed, Kim Perry began in the formula because of a magazine article on 750 published in 1972.

Bearing in mind the number of competitors and the Close, hard racing within 750F, beginners may soon be directed toward considering the merits of the 1300 category, in which 69 competitors were recorded last season. The emphasis seems to be much more on the old values of self-construction and quiet amateur self enjoyment from progressively developing and driving ‘one’s own brainchild. Of course there are noticeable exceptions to every rule and the informal conversation at lunchtime showed that amateur status can be a bit misleading when one remembers the people who are directly involved within the trade . . . garage owners, professional mechanics, and so on. There is no Silly talk of banning such people, but there is a bit of mumbling going on about some of the machinery we’re likely to see in the future, particularly the prospect of a 750 designed by a prominent F1 team designer and built by a mechanic from that team, though it seems unlikely that Carlos Reutemann or Carlos Pace will actually drive it! If one accepts that everyone in this life is not born equal, one presumably accepts that some people will always have the equivalent of what the Americans attributed to Roger Penske : “the unfair advantage”.

That advertising catch-phrase simply meant thorough preparation and some really original rule book interpretations. What people such as Kim Perry want is to try and rake back some of the advantage enjoyed by the 750s “professional amateurs” by sponsorship. There are attractions to the idea, for it is never cheap to go motor racing, especially if you want to be a front place contender. However, as Dave Bradley and the traditional majority rightly say, there are a lot of driver-constructors who

simply compete for the fun of it, often involved in weekly dices with those of a similar inclination. That kind of entrant can go racing for the under £500 figures that are quoted.

For somebody like Perry the engine can represent up to £380, the car an investment of £1,500 (it is up for sale at £850, “and that’s much more than Club members want to pay,” says Perry apprehensively) and then there’s about £500 to cover running costs, entry fees and so on. If sponsorship were allowed, one can see how costs could escalate until, as Bradley baldly put it, “we’re in the same bracket as Clubmans. We’ve always found it best to be distinctly different from them, at a lower cost end of things, otherwise there isn’t room for both formulae to-grow.”

“I have been the full time Secretary of the Club suite 1969, and I think that the growth, particularly of 750s has been amazing. People often ask me why this is, and I think there’s two main answers: a more commercial promotion of the Club’s activities, particularly with the press, and,secondly, the higher speed of the cars nowadays. Perry’s record at Brands Club is how well under the minute (57.4 sec./77.77 m.p.h.) and I think anyone who has driven or spectated at Brands will know that’s definitely not hanging about. Incidentally the 1300F record at the same circuit is 52.4.,sec./85.19 m.p.h., so you can see there’s worthwhile margin of extra speed to be had by graduating to 1300s.”

The Club have also considered imposing a tyre company monopoly on their formulae in the hope of reducing costs, a practice that is widespread at every level in British racing at present. However, since most Club members acquire their tyres secondhand from a variety of sources, it was felt this was not on. A lot of the machinery runs on 10 in. diameter wheels and rubber-wear that traces back to Mini use, though Perry has been clever in acquiring some hill-climb Firestones of sufficiently soft sprinting compound to blend well with the agile DNC’s all-up weight of 754 lb. The Messer, scientifically weighed via the miracle of bathroom scales placed beneath each wheel, is said, with a grin, to be “about 7 1/2 cwt.”.

Both cars use Revolution wheels, the consensus of opinion being that you could not tell the difference between Revolution and Minilite in lap times; that the Revolution was both strong and light, but, primarily, it was much cheaper than the magnesium Minilites. Messer also has Firestones, in this case of 13 in. diameter.

Technical and driving impressions

The first car to be fired up for our attention was the Messer. This machine is the well-developed result of some very hard racing miles since the car was originally built with an all-enveloping body. Construction, and by far the most driving, was the responsibility of Jim Ravenscroft, while Keith Messer has the credit for some of the design in the early days, and all of it since 1974, when the car was built up in its present form. Now the car is also up for sale, and Messer comments, “prices have doubled in the last five years, but we can still only ask £1,000 for a machine worth more like £1,400… it’s simply not on to ask for the real price of a car inside the club.”

To replace the 2A, Messer and Ravenscroft have a monocoque open Messer 3 with the tub already constructed : the 2A has a space-frame chassis. In a clubby formula like 1300 the advantages of tubular frames, such as ease of repair and crash damage costs, tend to outweigh the rigidity and strength pluses found in a good monocoque. That hasn’t stopped a few people competing successfully in 1300F with monocoque construction, but such chassis are banned in 750.

Messer 2A’s space frame is covered by simple NS4 gauge aluminium Sheet panelling, with foam filling backed onto the inside of the side curvatures. The cockpit certainly looks as starkly compact as one would expect, its silver sheeting relieved by a tachometer (the tell-tale pinned on 8,500 r.p.m.), combined oil pressure/water temperature gauge, and a separate instrument, also by Smiths, to cover oil temperature.

The tiny steering wheel hid some of the smaller dials when we were packed within the Willans safety straps, but on a cold and dusty track, the instruments could hardly find anything to measure on the heat side, while the driver was much too busy trying to keep cold tyres working on frozen concrete to worry much anyway.

Front suspension has the traditional DIY constructor’s friends, including Triumph Herald/Vitesse parts as it does. Front unequal Length wishbones and anti-roll bar comprise a layout that could easily have anti-dive characteristics built in, but at present the owners— unlike some other successful 1300F contenders—do not find anti-dive beneficial. The rear layout has reversed wishbones at the bottom, and single top link, the whole design built with a degree of anti-squat incorporated: no anti-roll bar is installed. Armstrong shock-absorbers are combined with coil springs front and rear.

As with cockpit dimensions; based on “two-seater sports cars,” the use of aerodynamics is restricted too, but the wing areas permitted in practice turn out to be considerable. Thus 1300 cars may well require considerably different chassis tuning to the 750s, which are not allowed rear wings. This makes for a basic imbalance and Perry not only has the usual quick suspension changes that he can make, but also includes the full width and narrow noses, the narrow nose decreasing understeer markedly on our slippery track.

I wouldn’t have thought a few sheets of aluminium would make much difference to the cost of 750, and it could be argued that 750 designers and drivers are missing a valuable part of their education, without rear wings.

Back at the Messer 2A we found the engine beneath a Lotus-Holbay cam cover is a delightful concoction of Ford parts. The cylinder block is of 1,500 c.c. origin, the head is a thoroughly reworked 1,000 c.c. component, while the connecting rods are from a 1600 and the crankshaft a toughened 1300 part. Pistons, valves, and camshaft are by Cosworth with a single sidedraught Weber, which incorporates the mandatory 28 mm. restrictor.

Naturally the Ravenscroft-Messer team have built up a stock of secondhand parts that enable them to build a replacement engine up cheaply and quickly, but they felt that £350 would still be a reasonable estimate to cover the parts involved in making one of their engines. Engine power has not been measured at the flywheel, but at the rear wheels a rolling road showed a maximum of 100 b.h.p.

Transmission rules are the subject of some discussion in 1300F. Banned are Hewland, Metso, or any other gearboxes or transaxles in which the gear ratios were originally designed to be rapidly interchangeable. Also verboten are limited slip differentials, automatic gearboxes and non-standard magnesium casings.

The Messer-Ravenscroft people feel that Hewland gearboxes would allow them the same kind of ratio flexibility that 750 men enjoy via the extremely wide choice of rear axle ratios available from Ford or Leyland live axles. As always cost is the reason for the rule.

The Messer uses a modified VW unit that sounds complex: within the standard casing are four closely spaced forward ratios, made up by Edmonton Tool and Engineering Co. Ltd. The differential and side plates are Hewland; no synchromesh is provided.

Girling disc brakes are of 9.8 in. diameter at the front, and 10.3 in. diameter rear on the 1300, while the 750 makes use of amazingly progressive drum braking of Triumph Herald ancestry, augmented only by Ferodo VG95 linings.

Once in the Messer, exterior glitter is backed by comfort and control. The foam rubber over the seat does not look elegant, but it fitted my stumpy frame well, especially when the sadistic personnel had the harness tightened fully, crotch straps and all. The engine fired very swiftly when hot—in the early morning the team had to practise Voodoo to get any sign of life—and the steering was light at low speed, even with 8 in. wide front wheels and 10-in. rears. Pure slicks are not allowed in either formula, but the lightly patterned tyres that are used instead were nowhere near working temperature, owing to the predominance of open windswept bends at our test track. Thus the quick steering was used to the full every time we entered our twisty handling course for the cold rubber had to cope with a second, gear right after a fourth gear spell of over a mile. This was good fun, even within the restraints imposed by preserving somebody else’s machinery, and we found the car very nimble and stable when it was then immediately commanded to go hard left, immediately afterwards. Above all the Messer provided a very stable base from which you would quite happily race others, and do astonishing tricks as the car forgave your inexperience.

The engine really had quite a kick, even with the silencer installed for this test. Taking it up to 8,500 r.p.m. in first and second provoked a good deal of wheelspin, and the need to correct on the steering, so you felt you were driving a real racer. The lack of synchromesh was quickly forgotten when pressing on, as the change was very quick, and lacked the usual baulkiness experienced when you are acclimatising yourself to such a gearbox at slow speed.

Power seemed to come in from 6,500 r.p.m. and continue unabated to 8,500 in the first three gears. Matching the acceleration perfectly were the very polite brakes, which exhibited plenty of retardation and no sign of snatching. Altogether this car reflected the years that have been profitably spent developing it into a very effective machine that is a pleasure to drive.

Messer 2A recorded a first place late in the season, after a second and a third had also been recorded, other lower placings bringing it into seventh overall in the 1300 series. The 1975 1300F championship went to the self-designed space-frame car of Bob Davis, who only started racing three years ago. Davis says his 20 races (best 8 scores count, as they do in 750) cost £1,000 and that he hopes to be back in the category, with a new car, next year.

Kim Perry has all the hallmarks of being something special on the driving and constructing front. He is 26 years old now and he won last year’s series in fine style: 11 wins in 19 races and 5 lap records. Perry also finished second on three occasions and third twice; the car never failed to finish a race in his hands, and it also never finished lower than sixth overall.

Although Perry does all the work on the car that you could reasonably expect, and his team consists primarily of himself and brother Ian, you sense that this is not the kind of man 750F is expected to attract. Perry is a real racer, with a streak of aggressive determination that shows, and which will probably find just the kind of competition he is really looking for in Formula Ford this season, as he is to give up 750.

Not that his Championship was a walkover. On the Contrary he had some good tough races, and really feels he owes 750 a great deal for the amount it has taught him about race tactics (“I was so green, I used to let them past in the beginning,” he comments ruefully) and sorting out the track performance of a motor car.

The chassis, manufactured by Centaur Engineering and purchased through David Newman, was acquired in 1973. After his racing experience Perry would probably prefer to build his own chassis next time, but he agrees it is important to learn a little bit on the track before plunging into your own design. Traditional flat alloy panels cover the simple 2 in. by 2 in. ladder chassis and tubular frame, and the cockpit again has to comply to those two-seater sports-car dimensions.

In fact the regulations covering 750 are considerably more restrictive than 1300, including a requirement for a proprietary rear axle (Kim uses a shortened and offset Minor 1000 unit) and gearbox, which is Reliant’s close ratio model, lacking synchromesh only on first.

The engine was built from the cannibalisation of two secondhand Reliant Robin 700 four-cylinder aluminium engines, which were then modified to bring the capacity to 748 c.c. This means a bore and stroke of 62.55 by 60.96 mm. using an EN16 iron crankshaft manufactured by Reliant. Perry was able to use the standard 700 connecting rods, but the cylinder block needed new liners and pistons to go with the capacity increase. Both crankshaft and rods were put through the Tuftriding process and crack tested, the latter technique being utilised pretty frequently through the season as Perry uses a regular 8,500 r.p.m. Previously up to 9,500 revs were applied, but the block bent on one occasion, and that detuned both driver and car!

The cylinder head has to remain of the original casting, but Perry has a freelance cylinder head modification man who does the handwork and installation of the larger Newman valves. A 22 mm. restrictor is placed in the carburetter venturi, Perry making use of the twin choke Dellorto with only one choke in operation whereas many others make use of the downdraught Weber. Perry selects his camshafts from David Newman too, measuring up each example in much the same was, as a blueprint specialist would assemble a Group 1 motor.

The result should be a superb little screamer, but we were very unlucky with our choice of silencing for the car, and we really could not assess it properly. The exhaust system allowed the car to accelerate quite passably between 4,500 and 7,000 r.p.m., but this 750 is really about winding from 6,500 to 8,500 r.p.m., providing nothing at all below 6,000 revs.

We were able to find the worth of the conventional wishbone front suspension and a quickly adjustable front anti-roll bar, Perry swiftly slackening the roll bar’s effect when he swopped over to the narrower nose for our stint. The rear axle is restrained by long parallel links, top and bottom and a Panhard rod. Spring rates are right in the soft production car bracket with this low unsprung weight, the brothers finally settling on 90 lb. sq. in. front and 110 lb. for the back: Spax adjustable dampers are used throughout.

The overall result was a very easy-to-drive competition car with engine’s wildness restrained by the exhaust bung, the brakes coming as a real surprise, as they were certainly the smoothest drum operation that I have encountered. There was rather too much understeer on our cold track, and the ride had that fantastic belt in the kidneys hidden in store when you went over something that really did not look like a bump.

I wasn’t keen on the oil pressure receding from 60 lb. toward 40 on our long straights either. Kim did explain that one in terms of some obstruction in the dry sump system, but it was at least obvious that the system works very well indeed through corners.

Neither of these two formulae seem to have done anything but improve quite dramatically since I last tried such cars in 1969. Long may they continue to provide a fresh air start to those with ingenuity and little money who want to enjoy their sport.—J.W.