Best way to clean out water jackets

Did a search and found these two quotes related to Doug Dutra, the first with a link her to the entire article.

http://www.slantsix.org/articles/dutra-blocks/slant-blocks.htm

"A comment on block cleaning: First remove all the plugs and get the blocks "hot tanked", then take a close look at the water jacket area. If the water jackets still have rust, scale and casting wires inside, you may want to "acid soak" this area to get them spotless. You have to plug up all the openings, then use a strong solution of sulfuric or muriatic acid (swimming pool acid) to "etch out" all the crud, including sintered core sand and core wires left behind from the casting process. Doing this will remove unneeded weight, increase coolant flow and will keep your cooling system / radiator clean. You can also spot any casting problems easier when the block is completely clean."

"Doug Dutra is the expert on this. He seals up the block using a head and gasket along with rubber expansions plugs. Then he sets it on end with the water pump cavity up. Then he fills it with a stiff solution of water and (In order of effectiveness) sulfuric, muriatic or phosphoric acid. Let it sit for a least 24 hours, if the solution quits bubbling before that, drain and refill. Now drain the block and refill with a neutralizing solution of baking soda and water. This procedure should leave you with the cleanest water jackets in town. If you are going to use a block filler be careful not to let any oil or WD-40 get on the inside surfaces."