[alan]

just built a 40 engine-boiled the block-dug around with all sorts of wires/tools/speedometer cable and then sandblasted internaly and you would not beleive what came out-pieces of the spruil that held the sand castings, the back of the block was packed with crud-spent over 2 hours digging it out and then pressure washed with hot water, the block again after boring and still more junk came out again. So yes I would beleive the crud that came out. Going to the store for some vineger today