Well before Giotto Bizzarrini ever made a car under his own name, he gained a reputation working with companies such as Ferrari and Lamborghini. His aim was to beat these past employers on the track, but that also meant selling road-going versions to help pay the bills. Alongside the 5300 GT Corsa, Bizzarrini offered the 5300 Gt Strada which was specifically meant for grand touring.

The 5300 GT stems from a long and complicated relationship between Bizzarrini, Giugiaro at Bertone and Renzo Rivolta. These three worked together to create the Iso Rivolta 300, a flagship car for Iso, having a welded sheet steel monocoque and Corvette V8. Due to sporting nature of the chassis and the reliability of its American power, Bizzarrini wanted to go endurance racing but Rivolta, who owned Iso, did not agree.

Fortunately, by 1963, Rivolta was finally convinced to finance the development of a more sporting Iso Rivolta. The result was the precursor to the 5300 GT, the Iso Grifo.

Both Bizzarrini and Bertone worked extensively on two cars which debuted at the 1963 Torino Motor Show. To satisfy Rivolta, both a competition Grifo A3/C and a 2 + 2 Grifo A3/L were displayed. These cars had distinctly different bodies and different design objectives, but were in many ways the same. Both Grifos were styled by Giugiaro at Bertone, used the same chassis and the same engine. Immediately after the successful show, both versions of the Grifo were put into production.

All of the chassis were built in Bizzarrini’s workshop at Livorno. Iso provided the engine and other components. Drogo manufactured and delivered bodies for the competition cars to Livorno for final assembly. The A3/Ls, the 2 +2 grand tourers, were finished at Bertone where Bizzarrini shipped bare chassis.

Bizzarrini really considered the A3/C to be his own. So much so, he registered the mark Grifo and put his own badges on some of the cars. After the death of Renzo Rivolta in 1965, the relationship between Bizzarrini and Iso ended with only 25 Grifos built. Bizzarrini then sued Iso to acquire the necessary parts and finish 50 cars himself at Livorno. Without Iso, all cars after chassis #0224 were named Bizzarrini 5300 GTs and finally Bizzarrini’s name graced his design.

The Iso Grifo AC3/C and Bizzarrini 5300 GT were very much the same product. When Bizzarrini took over full production, he had all the bodies assembled by Carrozzeria BBM instead of Drogo. Small design details were introduced on the BBM body including different door handles, rear lights and front signals.

Bizzarrini offered the 5300 in two variations. As a Strada, more interior appointments, including ventilation, were standard . For the racing client, or adventurous customer, Bizzarrini offered the Corsa version with a tighter steering ratio, hot engine, lightweight body and no seat belts!

The 5300 was based on the Iso Rivolta 300 chassis. It was a welded sheet steel tub having a fully independent suspension by double wishbones in the front and a De Dion axle in the rear. These same characteristics were lent to the Grifo and 5300, albeit in a shorter chassis.

Unlike all Italian sports car tradition, Bizzarrini used an American engine for the 5300, specifically the Chevrolet V8. With this engine came a host of benefits: it was ample in power, cheap to purchase and maintain, simple to tune and best of it all, it would run reliably all day and all night. After moderate tuning, the engine provided 365 bhp, keeping it well ahead of Ferrari’s 275 GTB.

Using lessons learned with the Ferrari 250 GTO, Bizzarrini pushed the heavy V8 far back into the engine bay as possible. When combined with the side-mounted gas tanks the weight balance of the 5300 was very close to a perfect, even during different fuel loads. One major drawback to this engine location was the intrusion of interior space which put the pedals at about mid-engine. Being so close to the engine, road going 5300s got very hot in the cockpit despite added interior ventilation.

Like a race-car, the interior space seemed planned as an afterthought. Both the speedo and tach were located centrally with temperature and oil pressure gauges in front of the driver. Furthermore, very little insulation was provided to stop heat and noise from reaching the occupants.