Originally Posted by Jeff Wills

Good for you. Back when those were a new thing (late Jurassic period, IIRC), those were responsible for a number of ruined BMX cranks. Kids would buy the cranks, put them on at home, and never get them tight enough. A few weeks down the road, they’d come loose and the crank would be ruined. It’s a testament to the original installer that they’re still intact after 40+ years.

After rebuilding the bottom bracket, reinstall them with a hex bit on a torque wrench. You’ll see how much that poor little Allen wrench had to put up with. A better idea might be to remove them entirely (there was a special tool for the ring) and use a standard bolt.