oil pump failed
My buddy ran over the infield berm and smashed the bottom of the oil pan on the 351-C in our dirt car. I didnt have a working oil pressure guage in the car that night...ran a 25 lap feature on a 1/4 mile track.
After we installed the new op gauge we saw a big zero on the gauge...found the oil pump laying in the pan... reused the bearings...light scuffing on the pistons. Ran the engine another season and a half with no issues.
You may have similar results.