cleaning up the slant six head

Experiment not so successful.

First issue was that Vinegar would not touch grease.

Pulled head out and dipped the head in water/dawn dishwashing fluid. Let it sit overnight thinking that would rid the grease. I figured I would de-grease it and stick it back in vinegar.

There was some sort of reaction with machined surfaces only, they had gone soft, I can scrape tha cast iron away down to the depth of maybe a business card ( more likely less )

Vinegar did not affect the non-machined surfaces, did not seem to affect any of the valve train parts, did not seem to affect the valve seats, as far as I can tell it only affected the machined surface where valve cover bolts on, intake/exhaust surfaces and of course the mating surface between the head and the block.

Dont know what to make of it, I had searched all over the net and Vinegar was what was being recommended, time or ratio was never really detailed out in any of the posts I had read and after doing another search this A.M I still see no posts from people that have had this issue in the past.

Maybe the head is junk at this point, I planned to have all the machined surfaces machined anyway for various reasons and not overly concerned with valve cover mating surface since I feel I can clean that up pretty well by hand with a scraper.

Any thoughts?

No that is not head gasket material I am scraping off, that is cast iron, wont scrape any deeper, it is normal hard cast iron under that thin layer of soft cast.