He wanted a very seasoned block so he went to the junkyard and got his motor out of a school bus, thinking that the hot/cold cycles, the heat expansion and loads would make an engine more durable than a new block.
"My theory was if I got a block out of a truck or a heavy unit that had been hot and cold and pulled a lot of weight, that block would have already done everything it was ever going to do," he recalled in a 1996 interview. "So we were at the junkyard, and there sat a bus and it was a Chevrolet and it had what we wanted.
Rager just missed qualifying at the brickyard by one spot in 1979. He did make the Indy 500 field in 1980 with the 10th fastest qualifying time, at 186.374 mph, faster than veterans A.J. Foyt, Tom Sneva and Gordon Johncock, and by the 16th lap, he was leading the race
https://en.wikipedia.org/wiki/Roger_Rager
http://www.espn.com/espn/wire?section=auto&id=2456837