A good example of a stitch welding repair on a Car SOS programme yesterday, repairing an axial crack in a cast iron cylinder head of an Austin 12.
What wasn't clear from what they showed is how they achieve a perfect seal: the crack was cut out and replaced with a hand-fettled insert, before stitch welding across it, but it wasn't obvious if any sealant was put in during assembly or applied afterwards. You did see them finishing off by peening but surely that is not enough?