DSE block

So, I have the head off my DSE and was cleaning up the holes for the head bolts in the block, and realised that every one of them has a helicoil insert.

Now, either that's how they all are, which would be odd, or they've all been damaged and rethreaded, which would also be odd.

I'm assuming the latter, as I've noticed a few 'bodged' bits as I've gone along?

No idea, but the block is cast iron so I would not expect to see helicoils.