Out of frame rebuild

Depends how much you're going to do to it.

 

Side question What else besides a bad crank and line boring would require pulling the block out?

 

At that mileage I would prefer to deck the block top and bottom to square it up. I know this is not a normal practice. But once you square up a seasoned block, you normaly will never do it again.

Most blocks at a million miles have a twist to them.

 

You can deck the top with it still in the truck. Not sure why you would deck the bottom. Or for that matter how the bottom could wear off square. Or are you talking about line boring it for the crank and grinding the main bearing caps?

 

Nope. After a million the block has a twist. Take some of the top and bottom to square everything up. It will be the best block you ever have. New cast block and all the heat cycles/ torque, its twisted. You square it up. And now that cast iron is "seasoned" thru that many heat cycles. Tru that block up top and bottom and it will stay square. More for a higher end build. Not your Chicago Can hauler. Some guys with cats have a head gasket problems after a rebuild with correct liner protrusion. A N14 after a million should be line bore. I suspect if you picked at them. They all could use it. But I would not recommend rebuilding a N14 for HP without it.

 

I guess what I'm not understanding is what in the bottom could need squared. The only thing on the very bottom of a 12.7 is the oil pan bolt holes. That's why I thought you meant the bearing caps and cap mating surfaces, but that's standard procedure with a line bore

 

Ok, I'll try and explain it different. Imagine a twisted pretzel. The whole block has a twist. I'm talking square top to bottom. Not just flatting top and bottom. Geometry my boy.