So my buddy picked up a 4.0 block had a machine shop machine the head of the block and wash it, He being my buddy proceded by painting the engine red ...Hemi red ..looks actually pretty neat but i started coming around on his build and noticed corrosion all over the inside of the block around the cylinders just chunks of it ...that leads me to my question what can be done to remove it and will it hurt anything ?

Im asking because im doing the same thing except im looking for a new 4.0 I6 Block

 

If block was simply washed and not boiled, that would be a FAIL!

 

When you say washed it, I assume they hot tanked it? If so, the rusty places you see in the water jackets begin to rust before they even have time to dry out.(surface rust) I'm thinking the 'chunks' you see are normal. The 'non machined' parts of the block are nowhere near smooth due to the way they're cast. Look closer at the chunks.. maybe pick at a few of 'em. I don't think they're going to come off easily.