I usually use good 7808 rod and preheat the cast, ( some guys like to use flux, I don't bother) clean up your area, contamination is the biggest problem with any welding get it near cherry , just a little yellow , in color with a torch , this stress relieves the cracks and gets it malleable before you weld it , if you can v grind the cracks its helpful, lets you get more fill down into the crack. Lay the welds on thick and if needed make multiple passes, ensure good beads, I use the round circular pond method so your welds look like a little set of waves. apply heat with the torch as needed during cool down , gradually let it cool Cast will sometimes POP as it cools, Its funny stuff, either holds forever or cracks again relatively quickly