As far as the “when” I believe it was around 1985 when the World of Outlaws went with the 410 standard and other tracks and series followed suit. As was mentioned, the flash point was out East. Big blocks had been legal at the Pennsylvania tracks. Things started to get out of hand when some of the better funded PA teams, such as Al Hamilton’s, started using higher dollar all-aluminum Rodeck engines that checked in at over 500 cubes. It’s a shame that the big blocks were legislated out of the sport. A lot of inventory was made obsolete. Those old big blocks sounded great too!