You also have to remember that they alloys used to build todays engines are much better that what they used back then. But then again, I've seen old engines with just as many or more miles than the average late model with no rebuild. Good example, my own 235. 236k miles, head had never been off. It did have a burnt valve on #5, and broken rings in every cylinder, but it ran very well and didn't smoke much at all.

Bill Burmeister