I can reccomend Smokey Junick's 3 books if you all are interested in this period of Indy racing. He states that if you let the steering wheel go when the engine was up to speed, you would be lucky to get a grip of it again, as the engine vibration made the rim grow to about 4 " in diamater! Those Offies were 4.2 litres and only 4 cylinders.