by Scooterdude » Wed Sep 27, 2017 9:57 pm
For those of you with an interest in welding cast iron it's a very specialised operation and not something to be done like say welding to mild steel plates together: we used to work with a specialist welding company called "Cast iron welding services" (the clue's in the name haha) in Leicestershire who specialised in repairing cylinder heads off ships as they used to crack on a regular basis, some of these things were 3 or 4 foot across and the same or more deep (this is an individual head per piston/cylinder) what they did was to cut the crack right back with a die grinder and burr (they usually went between the valve seats) place the head on 3or 4 fire bricks on the floor then build a firebrick enclose around it with a couple of small openings and put a fire blanket over the top then place a couple of gas burners within the openings and sometimes leave to heat up over night, once they were cherry red they would remove the fire bricks and weld the crack using an oxy/acetylene torch with a cast iron rod and flux, once welded they would rebuild the fire brick surrounding and reheat then leave it to cool completely before crack testing and machining. So as you can see not a straight forward procedure.
You just won't be able to weld a strengthening piece behind that exhaust stub like that at best it will look ok for a while then fall off or at worst you will crack your cylinder turning it into an expensive piece of scrap.