Originally Posted by DIGnLIFE
I have a lot of experience with cast. You need nickel rod and arc for sure. V grove the crack/ joint with a grinder. Pre heat with a torch. Weld it. Nickel rod burns alot different than most arc rods. I would suggest you try a couple times on a scrap manifold to get the feel and heat right.
Lots of preheat, and cool slow. I've put a welding blanket of cast after I've welded it to help keep it hot. And I've actually stuck some pieces in the rod oven to keep them hot and cool it slower.