[Rick Parker]

Understandably there has been a lot of development with manifolding, 4 bbl carbs, camshafts AND exhaust headers. But iF i had to hazard a guess, I would say the IDA's were used because they definitely increase the Torque of the engine significantly, and with the number of turns (road racing), being able to squirt from one corner to the next quickly was a major advantage. Also remember that the 327 Corvette which was much heavier was its only rivalry for 2 or 3 years. Once the 289s were put into A production (with Webers) they were pushing their luck, since they had to compete with cars with larger engines albeit 4BBL Carbs.