The design formula underlying the Italian ISO Rivolta car is a familiar one these days: it is to lay out a high-class chassis embodying as many standard components as possible from well-established suppliers (brakes, suspension parts, steering gear, transmission, and so on), to equip it with a large, inexpensive American engine with a high power output, and clothe it in a sophisticated body preferably bearing the hallmark of some eminent Italian coachbuilder.
If the job has been done successfully, the end product should be a grand touring car — albeit a hybrid — with all the performance and road manners of a thoroughbred, but at lower first cost. The formula was pioneered by the Anglo-American Railton of the ’thirties, based on the Hudson Terraplane. Current exponents include Jensen C-V8 vs. Bristol 410 and Gordon-Keeble in this country, Facel Vega in France.
In most fundamentals the resemblance between the ISO Rivolta and original Gordon G.T. prototype of 1960 seems more than coincidental, although the latter’s multi-tube frame is replaced by an integrated box-section chassis. Front suspension has the orthodox arrangement of unequal length wishbones with coil springs; at the back is a de Dion axle located by parallel radius arms and a transverse Watts linkage, with inboard disc brakes (unlike the Gordon-Keeble) and Salisbury limited-slip differential; a Chevrolet Corvette vee-8 engine is mated to a General Motors four-speed manual gearbox. Even the two-door four-seater body by Bertone is very similar in outline and main dimensions, although its individuality is clear-cut.
|1964 ISO Rivolta IR-340 MAXIMUM SPEEDS AT TEST|
One must not be deluded by the outstanding abilities of this car in terms of performance — as suggested by a glance at the graphs and figures — that it is a sports model in which speed and acceleration have been given precedence over space, comfort and proper amenities for long-distance travel. In fact, the reverse would be more true. The ISO is certainly sporting in character, but it can carry four people in reasonable comfort, with headroom to spare and with enough luggage space in the boot for holidaying. The weight penalty of proper sound insulation and such luxuries as electric window-lifts has been accepted.
ISO Rivolta IR-340
In fact, the car tested was fitted with the hotter of alternative engines offered, having a relatively high compression ratio (11.25 to 1) and mechanical valve tappets. Most people would probably be more than satisfied with the standard IR-300, with the quieter hydraulic tappets, 10.5 to 1 compression and stronger pull at low rpm. The difference in out-and-out power is between 340 and 300 bhp gross, and the greater mechanical refinement and tractability that go with the lower output seem better suited to the car’s character. Moreover, it should impose lower stresses on the transmission and result in greater reliability from these components. With 340 bhp under the bonnet we soon ran into clutch trouble, this component calling for very discreet treatment when getting the car off the mark quickly on its very high, 60 mph first gear. Another fault that developed was that third gear would jump out under full load and at high rpm.
|Standing 1/4-mile: 15.9 sec, 91 mph|
|Standing km: 26.3 sec, 117 mph|
Our test of the ISO Rivolta was interrupted more than once by a variety of troubles. In addition to the clutch, these included repeated fuel starvation at high revs in top genr and failure of the jockey pulley bearing for the alternator and water-pump drive. The fuel starvation problem seems now to have been solved by the fitting of a larger-bore delivery pipe from the tank. In tin’s connection the development work undertaken for the benefit of British customers by the U.K. concessionaires is worthy of mention.
While the ability to exceed 140 mph is really beyond the requirements of any motorist today, except in competitive events, 120-125 mph has become quite a commonplace speed for fast drivers habitually covering long distances on European motorways. The very high maximum is an assurance for such people that there is a big reserve of power at 120 mph or so, enabling this speed to be reached very quickly and without strain, while keeping the engine down to safe rpm for continuous cruising on a high final drive gearing. In the case of this ISO Rivolta 120 mph represents about 5,000 rpm, whereas peak power of the Corvette engine occurs at 6,000 rpm. In top gear one can reach this speed from 100 mph in only 11.2sec, and from 120 mph one can still sense quite a push in the back when the carburettor’s four throttles are opened wide.
|Fade (from 85 mph in neutral)|
|Pedal load for 0.5g stops in lb|
|Response (from 30 mph in neutral)|
|10 lb||0.18||167 ft|
|20 lb||0.30||100 ft|
|30 lb||0.55||55 ft|
|40 lb||0.75||40 ft|
|60 lb||0.95||31.7 ft|
|Max gradient||1 in 3|
|Kerb, 30.6 cwt/3,423 lb/ 1.553 kg|
|(Distribution F/R, 49.9/50.1)|
|Test, 33.6 cwt/3,759 lb/1,705 kg|
|Max payload 794 lb/328 kg|
Front seats have adjustable backrests, and trim in this ease is leather — even to the stitched padding beneath the facia. Frameless door windows have electric lifts. The back seal is comfortable and quite practical.
A big, sensibly shaped boot corries the spare wheel beneath its floor, together with the tool kit. both bonnet and bool lid have self- supporting struts, neither strong enough to cope with a high wind.
With maxima in the three close-ratio indirects exceeding 60, 80 and 100 mph there are few cars indeed that can compete with the ISO Rivolta for sheer acceleration. Stepping off the mark very gently in order to preserve the clutch faces, we still reached 60 mph in 8 sec and 100 mph in 18.6. Earlier runs had achieved two zero-to-60 times of 6.9 sec and two over the standing-start quarter-mile in 15.1 and 15.2 sec. In fact, wider gear ratios, and in particular a lower first gear, would better suit the car for day-to-day running. Despite the big engine’s tractability at low rpm one’s left foot is kept rather busy on the clutch pedal in dense city traffic.
There is a choice between three final drive ratios, incidentally — 2.88, 3 07 and 3.31. The 2.88 gear is standard for the comparatively low-revving 300 bhp engine, the 3.31 for the 340 bhp one as tested. Equivalent road speeds at 1,000 engine rpm are 26.2, 24.6 and 22.8 respectively, disregarding expansion at high speed.
For our high-speed runs the engine was fitted with “hot” sparking-plugs, which we were told should not be necessary for more normal motoring. Even the “soft” variety was apt to foul in slow-moving traffic, but could always be cleared quite quickly on reaching the open road. This was just as well since a change of plugs is quite a task.
|Overall mpg:||17.2 (16.4 litres/100km)|
Hard 11.6 mpg
|Driving Average 18.0 mpg|
|and conditons Gentle 20.5 mpg|
|Grade of fuel: Premium, 4-star (97 RM)|
|Fuel tank: 15.5 Imp galls (70 litres)|
|Mileage recorder: 1.6 per cent short|
|Official fuel consumption figures|
|(ECE laboratory test conditions;|
|(not necessarily related to Autocar figures)|
|Urban cycle: 15.8 mpg|
|Steady 56 mph 28.3 mpg|
|Steady 75 mph: 23.4 mpg|
|(SAE 20/50) 800 miles/pint|
In addition to making considerable clatter from its valve gear at low rpm, the engine of the particular car tested passed through a minor vibration period at around 2,000 rpm, and another more pronounced one in the region of 4,000 rpm, perhaps suggesting the need for more development work on the flexible mountings. The starting was trouble-free, hot or cold, the automatic rich mixture device avoiding any stall problems yet cutting out promptly. Although the overall fuel consumption of 12.1 mpg may seem rather heavy, one should bear in mind that a high- performance car on test is inevitably driven hard and fast wherever possible; in everyday use we think most ISO owners could expect around 14.16 mpg in U.K. road conditions without making a special effort to economize.
Even without the optional limited-slip differential, the combination of a lightweight De Dion axle and high bottom gear results in the ISO having no wheelspin or axle tramp problems. On a dry surface a sudden burst of power, for instance, when leaving a roundabout, produces no unforeseen tricks. Its behaviour in the wet is also entirely normal and predictable, although one naturally has to treat such a car with extra discretion when coming to it fresh from less energetic machinery. In the right hands the power can be used to help control the ISO which, if a hybrid by birth, certainly has the road manners of a thoroughbred.
Its suspension provides superb stability at high speed — maintaining its equilibrium even when traversing those tricky stretches on motorways where subsidence of the foundations has created a succession of long-pitch waves. Yet it has no sports car harshness at more normal speeds, riding as comfortably as many family saloons over indifferent surfaces. However, in our view the seat cushions are too springy, accentuating road spring movements, the overall effect being too bouncy a ride for this class of car. Armstrong Selectaride dampers, with four-way adjustment through an electric switch, are optional for £40 extra including tax.
Bertone’s creations are always well-proportioned and interesting to the eye. The ISO Rivolta’s flanks are well protected by bumpers extending to the wheel arches and a rubbing strip beneath the door.
No room to spare around the Chevrolet Corvette engine, and plug changing is not cosy. The radiator fan has a viscous coupling, and an alternator charges the battery.
The ISO is unusual in having its weight divided almost equally over front and rear wheels, which results in an outstanding balance of control, with no under- or oversteer tendencies to contend with. It has faultless directional stability at any speed, and the steering mechanism gives responsive and accurate control. For our tastes it could be higher geared, but then the effort needed for low-speed manoeuvres, already considerable, would presumably be unacceptable. The minimum turning circles in either direction are very poor — a mean of 44ft 5in. between kerbs.
Large diameter Dunlop disc brakes — inboard at the rear — are vacuum servo-assisted and provide tremendous stopping power in keeping with the car’s abilities, in return for a quite moderate pressure on the pedal. For instance, a 1.0g stop without wheel locking — a further contribution from the symmetrical weight distribution — required only 100lb load on die brake pedal. While the handbrake held the car securely on 1-in-3, this slope was understandably a bit too steep for a restart on the 8.41 to 1 bottom gear.
The very handsome Bertone body is structurally rigid and obviously strong; its panelwork is excellent, as is the paint finish, and die leather-trimmed interior (leather being an extraordinarily costly extra, at £290) looks invitingly luxurious. In fact, on closer examination the interior detail is not all it might be for a car of this calibre, a criticism that could be levelled at most current products of the Italian specialists. From scats having perhaps less showroom appeal, but firmer cushioning and more shape, would better complement the special dynamic qualities of such a vehicle. The backrests are adjustable for rake, and there is sufficient fore and aft adjustment to suit drivers of any height, so long as their arms arc in proportion to their legs. Long legs combined with short arms would be awkward as the steering wheel is well forward, close to the facia. When the back seat is to be occupied those in the front may need to move their seats a little farther forward than they would normally, to leave sufficient space for legs and knees behind. Rear passengers have armrests over the wheel arches and a centre folding arm, and their side windows arc hinged from their leading edges.
An excellent driving position is centred round a wood-rimmed, light alloy steering wheel of only 15 ½ in. diameter, and with neat horn-pushes recessed into each of its three spokes. As is the custom with Italian cars, it is set rather higher relative to the scat than is customary on British cars, but being small docs not intrude in the driver’s line of vision. Its centre button is pushed in to flash the headlamps. Brake and clutch pedals are pendant, the brake being near enough the organ-pedal accelerator for so-called heel-and-toe operation. There is a comprehensive set of easily read round instruments, the big speedometer and rev counter seen dearly above the upper two steering-wheel spokes. A row of six identical tumbler switches in the middle of the facia can be confusing, particularly at night. Even though the only vital one — for the driving lamps — can be found quite easily as it is on the extreme left, it would be preferable to have this one isolated and more accessible.
Electric window lifts are a great convenience — even a safety factor — on a fast car; these ones were sometimes erratic in their functioning, however. In addition to a fresh-air heater, there are separate cold air vents and spherical outlets at each end of the facia, which can be set to keep the door windows clear. A fan to demist the back window is standard.
Powerful wind-horns are appreciated, although even these cannot always be relied on to stir a comatose potterer wedged in the fast lane of M1. The two headlamps are adequate on full beams, rather restrictive when dipped. Such items as a rear-view mirror with dipping reflector and electric screenwashers, perhaps go without saying. It seems surprising that such a fast car should not be equipped with dual or divided braking circuits. Routine servicing requirements seem to be very moderate, with only four lubrication points on the steering swivels and two on the propeller shaft universal joints requiring attention every 3,000 miles.
It may have been unfortunate that the ISO tested was one of the first right-hand drive ones, and it seems reasonable to surmise that examples reaching this country in more recent months would have matured to a state of greater reliability and improved detail finish. Clearly the designer has achieved his main objectives, to produce an exceptionally fast and safe touring saloon, very enjoyable to drive, that readily adapts itself to such humdrum duties as short-distance commuting and shopping expeditions.
1. Accidental Damage
2. Cooling System
3. Engine Originality
5. Inner sill
7. B-pillar (Grifo)
8. Biden sheet
9. trunk floors
10. Frames Front
11. Rear window frames
12. Door bottom edges
|UK PRICES in 1964||£||s||d|
|Two-door touring saloon||3,309||0||0|
|Total (in U.K.) 3,998 18 9|
|Extras (including P.T.)|
|340bhp sports engine||217||0||0|
|Car||1964 ISO Rivolta IR-340|
|Car type||Front, rear drive|
|Body||Steel body welded to boxed frame|
|Type||GM V8 327 block|
|Head/block||All alloy head / cast iron block|
|Bore, mm (in.)||100.6 (4.0)|
|Stroke, mm (in.)||82.6 (3.24)|
|Capacity, cc (in.)||5359 (327)|
|Valve gear||Overhead, pushrods and rockers, mechanical tappets|
|Carburettor||Carter AFB four-barrel|
|Max power||340 bhp (gross) at 6,000 rpm|
|Max torque||344lb ft at 4,000 rpm|
|Clutch||10.4in single dry plate, diaphragm Spring|
|Type||Four-speed all-synchromesh, floor change|
|Final drive gear Ratio||Salisbury hypoid bevel 3.64|
|Front location||Independent, wishbones and coil springs RIV telescopic dampers, anti-roll bar|
|Rear location||De Dion axle located by longitudinal radius arms and transverse. Watts linkage. Coil springs. RIV telescopic dampers and inboard brakes|
|Type||Burman recirculating ball|
|Turns lock to lock||4|
|Circuits||Dunlop discs with vacuum servo F. 11.75in. dia|
|Handbrake||Centre lever, rear drum within disc|
|Type||Cast all alloy 210 mm rims|
|Rim Width||6 1/2 in.|
|type||TRX radial tubeless|
|pressure||F36. R36 psi|
|Battery||12V 60 Ah|
|Screen wipers||Two-speed plus intermittent|
|Interior heater||Water valve|
|Interior trim||Leather or cloth seats, pvc head-lining|
|Jacking points||Two each side, under sills|