www.QV500.com - Iso A3/C & Bizzarrini 5300 Part 5: Bizzarrini 5300 GT Corsa & Stradale

By August 1965 and with A3/C production having barely reached thirty units, the relationship between Renzo Rivolta and Giotto Bizzarrini had gone sour. Largely due to Bizzarrini building almost the entire run of A3/C's with his own rather than Iso's emblems, the Tuscan engineer had also registered Grifo as a trademark himself. When you consider the A3/C's had been raced and marketed at the expense of Iso, Renzo Rivolta was understandably a little disgruntled. The two split and Rivolta acquired the rights to the Grifo name while in return, Bizzarrini was given enough component parts to construct fifty vehicles and the sole rights to build the A3/C.

So by late summer of 1965, Bizzarrini was in charge of building and marketing the A3/C himself, one of his first acts being to construct a development mule (chassis IA3 0332) on which new competition and production mods were tested. Come the autumn, the factory were offering their re-named Bizzarrini 5300 GT in either Strada or Corsa trim although customers could have some degree of cross-over if they so wished. Strada's began to dominate production as ever fewer Corsa's were commissioned, the new 5300's featuring a number of interesting differences over the old Iso A3/C's. While chassis's and engines remained much the same with the 5300 GT similarly available in 365bhp or 405bhp trim, these revised versions did feature some subtle aesthetic changes. No longer fabricated by Drogo’s Sports Cars of Modena, Bizzarrini shifted production of the 5300's aluminium bodywork over to Carrozzeria BBM just a few miles down the road. The new car got paper thin indicator lenses located beneath each headlight (to replace the A3/C's pods) while a decorative bumper strip now ran the width of those distinctive nostrils. Most Strada's still featured chrome-rimmed headlight cowls although Bizzarrini did make some changes to the engine-cooling arrangements. Giotto chose a variation based on the A3/C's side-mounted vents, his 5300's getting a smaller but more distinctive chrome-trimmed item ahead of the door and a five-louvred bank behind each front wheelarch.

Engine-wise, the competition-spec Chevy motors had their compression dropped to 10.5:1 to reduce detonation symptoms while four twin choke Weber 45 DCOE sidedraught carburettors were used. Corsa engines also featured polished ports and combustion chambers, high carbon connecting rods, hot camshafts and free flow exhaust systems, all of which meant 405bhp at 6000rpm. Cabins were much more basically trimmed and this helped reduce weight to just 1190kg. While the general specifications of these competition cars remained fundamentally unaltered, we're fairly sure Bizzarrini only built one customer car and another for the works, both of which were made in late 1965. Soon after though, some of the original components for those first fifty cars were beginning to run short and thus Bizzarrini began making a few changes here and there, the most obvious coming inside. A boxy new walnut facia dash, a smaller diameter wood rimmed steering wheel and more luxuriously padded seats were all phased in in an attempt to attract more clients from Ferrari, Lamborghini and Maserati. However, as a manufacturer in his own right, Bizzarrini always struggled to make money and by the middle of 1968, the firm went into receivership, closing down for good in 1969 after producing 67 5300 GT Strada's and probably no more than two Corsa's. However, a handful of these 5300's were completed as GT America's although at the present time we are unable to quantify exactly how many.