Bob,
I'm not sure if anybody reads our new automotive sections listed at the bottom of the forum page (you must scroll down to find it) but you might pop the question down there to see if it gets better response.

I've never tackled such a job, but as I recall my references suggest a bronze filler- they say to braze it. If nobody points you toward it there have been a couple of links posted to a military training circular on welding that would cover such repair. It's a challenge to manage the effects of heat on such a complicated casting and you will need facility to do so. I certainly wouldnt want to use a rare block with extensive damage as beginner practice.

If you are patient and do check back or renew the post from time to time you will get a response from someone with the experience you need.

Searches back to two years (if you can get back that far) in the archives of "technical" or "shop talk" should turn up at least one similar question, as well as that training circular.

Good luck
d

As long as the damage only involves a single passage and "outside" (say water), where "outside" is anything you can see, you've got a pretty good chance. Keep in mind that without seeing it this is just a guess. If it involves more (say "outside" and water and an oil passage) difficulty goes way up. As Dee suggests brazing is one approach, probably best done in a furnace. Some would weld using nickel alloy rods (so called machinable). There are people who make a business of this. I would suggest that you not practice on rare iron since this can go horribly badly. I have no name to suggest but construction equipment and heavy truck engine repairers (think Caterpillar) will probably be able to suggest someone. They have the same problem, horribly expensive cracked cast iron parts. Expect at least align boring after repair if not included in the repair. Good luck. Just curious- what is it.
Bill