How do I clean my block ?

YES, it is EXTREMELY caustic to aluminum... It pretty well ruins any aluminum it touches, especially if is nice finished aluminum . I'm a master of "learnin' it the hard way", its become a theme.

 

I second brake cleaner for the nooks and crannies.
As for the bulk of the block try some oven cleaner- I haven't personally tried it but have heard good things. Just make sure to wash it off after.

 

Ok I use a big GI trash can with hot water and tide. I use my cherry picker to raise and lower the block into the trash can. Rinse it with hot water , from my washer hookup, and dry it with compressed air. You can use long brushes to clean out galleys. I once built a fire under the trash can. Carlg

 

After I got my block back from the machine shop, I spent some time with a straightened coat hanger plunging and s****ing the water jacket trying to loosen any scale and crud the machine shop hot tank didn't break loose. Then I tapped all the holes. A trip to the car wash was next, couldn't believe how much **** came out of the water jackets, core sand, rust, junk. Back home, blow it out and wipe down with Blaster penetrating oil for ***embly that weekend.