Redesigning the GTV Prototype
The 350 GT shared a number of features with the 350 GTV prototype, including a four-wheel independent suspension, the quad-cam 3.5 liter Lamborghini V12, and an aluminium body. A number of mechanical revisions and refinements were made due to the suggestions of the Neri and Bonacini racing development shop and test driver Bob Wallace. The body was redesigned by Carrozzeria Touring, retaining the original profile while cleaning up details of the design to result in a more cohesive appearance. Most noticeable was the replacement of the prototype's rotating hidden headlights with fixed headlights.[2]
As equipped to the 350 GTV, the Bizzarrini-designed 3.5 liter V12 was essentially a race motor, potentially developing 400 hp-metric at 11,000 rpm.[6] In order to fit his grand touring car with a smoother, more pleasant, longer-lasting engine that would be "good for 40,000 hard miles between services," Ferruccio had Dallara and Wallace de-tune a version of this prototype GTV motor for street use.[4][2] This included:
This first "detuned" L350 engine was tested on October 3, 1963.[7] The result—later fit in the 350 GT—was a 270 hp-metric power plant that could reach 254 km/h in top.[4][8]
While this 350 GT design work continued, the 350 GTV prototype was rushed to completion for the upcoming October 26 press meeting and the subsequent inauguration of the Turin Auto Show on the 30th.[2][5] The 350 GTV was shown at the Turin Auto Show with the original Bizzarrini "racing" V-12 engine—with its downdraft Webers, rear distributors, etc.—displayed alongside as it was not "adapted to the chassis."[5] The car was a static display with the suspension arms simply tack-welded in place and the engine not installed.[4][5] Lukewarm reaction to the car caused Ferruccio Lamborghini to postpone plans for immediate production and move on to introducing Dallara's new 350 GT design.[4]
In March 1964, only five months after the debut of the GTV in Turin, the "redesigned GTV"—now called the 350 GT—was debuted at the Geneva Auto Show.[2] It was greeted with sufficient enthusiasm that Ferruccio decided to proceed with production in May 1964.[2][4]
- Replacing the elaborate and costly racing-style dry sump oiling system with a conventional wet sump system
- Reducing the compression ratio from 11.0:1 or above to 9.4:1
- Cutting back on the exotic materials specified for the crankshaft and other components to reduce cost
- Relocating the distributors to more accessible positions on the fronts of the exhaust camshafts
- Adoption of a single, very tall Lamborghini-made oil filter
- Replacing the expensive 36 mm down-draft racing Weber carburetors with conventional, less expensive side-draft 40 DCOE Webers. This resolved clearance problems seen in the GTV prototype and enabled the exceptionally low hood line Ferruccio desired.
- Softening the cam profiles for smoother running during street driving
