440 block horsepower limits

496 polara said
A buddy just sent his 440 to be refreshed and a piston change and should be grateful he did. Builder found severe cap walk and two of the main cap bolts were stripped 1/2 way down. 4.25 stroke that made 605 and was routinely hit with 250-290 shot of N20. Several hundred passes at least.

That is exactly what I'd expect to see on a 440 block that was making that amount of power for that number of hits. The production blocks just aren't designed to handle that much power for that long. The RB was designed in the late 50's to make around 300 hp at a fairly low RPM.