400 big cam Cummins

She's an 82 model 400. The tag is missing due to a total rebuild and paint job so i can't remember what it was supposed to be out the factory but she's pushing close to what it's rated for.
These engines are great and cheap to work on but as it's been stated they do have limitations.
My uncle is a machinist with 30 plus years experience at the local shop. Lol we have a guy locally that is contracted to the local mill that runs an 85 359 with a 400 Cummins. This guy has more money than sense and he's built that 400 to push around 650 hp however my uncle says evrey year it's in for an inframe due to holes being blown in pistons lol.