I've had my 235 spinning 4,500 rpm on several occaisions. But the stock cam/intake setup won't let you go that high. Usually you can't get a stock up to 4,000 rpm. What really kills these engines is lugging them low enough to knock, it really pounds the mains.
Just for grins, my friend has had his 261 over 6,000 rpm. But it has been balanced and ported so it will breath.
