Well when I think of welding, I usually think of some form of arc welding or mig and tig. Even though using an oxy/acetylene torch is still considered a form of welding(gas welding), it is a lot less thermally shocking to the parent metal because it involves a lot less temperature, and can be controlled more easily.I remember having to fix many of Cotton's heads after a combustion chamber was blown out, or dropping a valve, and using a gas torch and brazing rods to make to repairs. It sure beat scrapping a mega dollar "lump" head. The 250/292 L6 heads are a much lighter weight of a casting, than the earlier 235 heads, and are,as you pointed out more sensitive to welding and high heat. Im still in the beginning stages with this idea, and may find that some form of epoxy may be more practical as far as time and expense are concerned.
