The Magnification of your pictures make it look like the pits are deep. But
if they are minor I would check your wall thickness and roll on.

The pits are .020”, maybe a few at .030”, most of which is in the black scale. I’ll get the sonic checker back out and check the bored again just to be sure. Blocks are only .030” over

Thats more like sand pits from the casting core then , I wouldnt worry much , there is probably alot worse in there that we could never see.
And would never effect anything.

The pits create more surface area
More surface area creates better heat transfer(fins on air cooled engines) and more strength(ribs on metal roofing)
If it makes you feel any better.

Yeah never was worried about the pitting... just the potential Issues of the magnetite restricting heat transfer. No one worries about this I guess

Rydlyme.

https://controlscentral.com/tabid/63...container.aspx