Iso Grifo A3/C Chevrolet at rest. Piero Drogo’s Carrozzeria Sports Cars, Modena, Italy December 1964…
Renzo Rivolta was an ingenious Italian entrepreneur in postwar Italy.
He owned the Isothermos heater and refrigeration company and postwar decided to build cars, his passion. He started with motorcycles and then introduced the Isetta, an incredibly successful economy car he subsequently and very profitably licensed to BMW and others.
Into the early sixties he formed Iso Automobili and introduced the Iso Rivolta GT to rave reviews at the 1962 Turin Auto Salon.
One of Rivolta’s key players in his nascent enterprise was Giotto Bizzarrini, the gifted engineer who played a key role in the development of the Ferrari Testa Rossa and 250 GTO. After the so-called ‘Palace Revolution’ of 1962, Bizzarrini left Maranello with Carlo Chiti and others and soon found work as a freelance engineer, then with with Iso. There, Bizzarrini worked with Iso’s chief technician Pierluigi Raggi to develop the sophisticated platform type chassis which formed the basis of the 2+2 Iso Rivolta GT.
Bizzarrini, Bertone and others encouraged Rivolta to build a sports car to enhance sales of the Rivolta, which were flagging, partly due, its said, to the failure of the US importer to meet its contractual obligations. The result was the Iso Grifo two seater GT built on a shortened Rivolta chassis.
The chassis had a fabricated sheet steel platform as a base with tubular ‘space frame’ upper sections clearly shown in the photographs below. Two Iso Grifo versions were built and shown at the Turin show in November 1963. The luxury touring ‘Stradale’ A3/L (Lusso) was displayed on coachbuilder Bertone’s stand, while Bizzarrini’s race-prepped A3/C (Corsa) was long, low and lean on Iso’s stand.
Wearing lightweight aluminum coachwork penned by Bertone’s great and immaculately credentialled Giorgietto Giugiaro, and built by Piero Drogo’s Carrozzeria Sports Cars in Modena, the A3/C ‘was a spectacular vision with aerodynamic flair. The result was an impossibly low and wide car that was exotically curved from every angle’. Some regard the car as one of the most beautiful shapes Giugiaro ever created.
In an effort to avoid the cost, time and complications of engine construction, Iso specified a 5.3 litre Chev V8 engine which was highly tuned for racing in the A3/C. Depending upon specification the famous Chevy 90 degree, cast iron, push-rod OHV ‘small block’ V8 produced between 350 and 420 bhp. The latter spec involved steel internals, roller-rocker valve gear, 4 Webers and the rest, the car good for circa 180mph down the Mulsanne. In addition the engine was placed far behind the front axle, giving the car a very racey front but mid-engined layout that plonked all the masses right where they needed to be. The engine was mounted so far back in the chassis that the Chevy’s distributor, famously, had to be accessed through a removable panel in the top of the dashboard!
The gearbox was a 4 speed Borg Warner T4.
According to some historians, Bizzarrini described the A3/C as the second coming of his GTO, a more refined one at that.
Suspension of the car was conventional upper and lower wishbones up front with coil spring/damper units and an adjustable roll bar. At the rear a de Dion rear axle was located by twin radius rods and a Watts linkage, again with coil spring/dampers.
Burmann recirculating ball steering, 4 wheel disc brakes and lightweight magnesium alloy wheels (7X15inch/9X15inch wheels) completed a beautifully specified and integrated package.
The car was 4369mm long, 1730mm wide, 1135mm high, had a wheelbase of 2451mm, a track of 1410/1435mm front/rear and weighed circa 1000Kg
Bizzarrini provided full build execution for the AC/3 at his Autostar Works factory in Livorno, for 18 months Giotto built the car under agreement with Iso. Iso and Bertone produced the Grifo A3/L road car.
To Rivolta the Grifo was a tool to promote his GT car, but Bizzarrini was a racer to the core so fissures developed in the relationship between the two men as to where the primary focus should be. After about 20 examples of the Drogo-bodied A3/C’s were made, in the summer of 1965, Bizzarrini left Iso and produced the model under his own name, in both Strada and Corsa forms. As few as 115 examples of the cars were made under both names.
Most of the cars pictured in this article are some of the 20 A3/C coupes built using very lightweight, riveted (over 7000 of them were utilised in each body) aluminium bodies fabricated by Piero Drogo’s Carozzeria Sports Auto, the photos were taken in Drogo’s workshop in Modena in December 1964 and early 1965.
Part of the A3/C’s transition from an Iso to a Bizzarrini involved a change of coachbuilders from Drogo to Salvatore Diomante and his Carbondio concern, which was eventually reborn as Autocostruzione SD of Torino.
From a racing perspective amongst the cars best international results are 14th outright and 4th in class at Le Mans in 1964, 5th in the Monza 1000Km and 19th at the Nurburgring 1000Km in 1965 a season which started badly with one car destroyed at Sebring and then another at Daytona.
Given the cars low build numbers it raced as a prototype against outright class mid-engined sports-prototypes rather than amongst the GT cars more akin to the Grifo in specification.
Bonhams, Sotheby’s, Getty Images, Klemantaski Collection. Darryl Norenberg/The Enthusiast Network, The GP Library, F2 Register
Tailpiece: A car fit for a King. John Lennon susses the interior of his new Iso Fidia S4 at Earls Court in October 1967…