A question to those old enough to remember:
What maintenance was done to the Hemi Engines running i Nascar races during the 1960s and 70s?
I am thinking on expected life (number of races) of bearings, pistons, rods, valve parts etc.

Interesting question. I would think rings, bearings and valve springs would be changed every race.

Back when the 426 hemi where raced the teams had multiple engine and where allowed to change them from qualifying to racing or practice.
That being said as far as maintenance I'm sure the parts, metal, testing devices, machine work as well as lubricant are a lot better today than back then so I would use the tools available today to base all my decision on the maintenance of any motor I owned, raced or maintained

Back in the day, all the motors used by the NASCAR teams (all brands) were rebuilt after every race. 500 miles of WOT pretty well wore them out. That was often why the big teams had a motor for hot lapping & time trials and a fresh motor for the race.

A lot of times, the factory guys were supplied with new motors and instructed to sell off motors pulled after big races and sell them to less well funded teams, or to guys racing at lower levels. That was how so much of the good stuff made it to the local tracks. To some extent, it still happens today. Gene

I doubt there was any maintenance at all! Total rebuild. Go run something WFO for 500 miles and see how she feels?

Just stick another one of these in.