welding a block

[Floyd]

This is a subject that can go on forever like "what kind of oil should I use". Lots of opinions, some fact and some stories. I just went through a complete education on correctly welding cast iron by a company that does this every day on large diesel engines , blocks and heads. They do all the remanufactured blocks and heads and cranks for the big famous doesel engine manufactures that we all know. They weld cracks anywhere on an engine and typically large diesel heads have 20 to 50 major cracks it it when it goes to "reman". These parts go back into service with the OEM warrentty. Therefore these guys know what they are doing. I have toured their shop and they have repaired a block for me.
Without going into too much detail, they have a few rules for repairing cast iron.
Except for small parts or covers, etc. Cast iron cannot be repaired in the field. The entire part must be heated and cooled under controlled conditions. Do not try this unless you know what you are doing.
Brazing works great on cast iron for non structural areas.
Electric welding must never be done, it will eventually crack and leak. This includes the world's greatest TIG welder.
Only ox acetyene can be used and with a very very large tip.
Filler rod must be actual grey cast iron. Never use anything else, even the special nickel rods or any other "wonder" material. It will always crack later.
These cracks that we get excited about in our flatheads are nothing to the real guys. They can easily be repaired by the people that do this for a living.
Thanks
Floyd