Casting Marks or Concerning cracks?, Casting Marks or Concerning cracks? Engine rebuild Options

[Tking327]

Hello, i tore down my 1970 1.7L to rebuild it and on cleaning the grease off the top of my crankcase, i saw the attached which made me nervous. . These 'cracks' are located essentially all over the top of the crackcase but seem more pronounced right over the cylinder/piston entry points, and a bit more concentrated on the drivers side. Are these cause for concern or just casting marks? I can sand an area down to see how deep they go but figured i would ask first. (The engine had been running well but smoking and leaking hence the rebuild).

[Ninja]

Normal.

Now, that surface you exposed, where the base of the jugs sit, is one of the more common areas to have machined flat. That surface sags with age alone.
Sir Raby states it's almost never flat.

You have to pull the head studs and find a machine shop that is willing to machine it flat.

As it is lower than the case casting around it some machine shops don't have the equipment or knowledge to correctly mill that.