[cas3]

impact driver is trying to turn it. "shocking it" is a downward force. most times i want to remove things like , head studs for example, things threaded into a blind hole, the first thing i do is give it a good whack, a downward act of violence (in theory) will knock the threads a bit to allow some movement. even though your impact driver is supposed to do that, give it a good blow before starting with that tool to "soften " it up a bit . the block is tuff, i think you can get pretty wild without breaking anything. brians thoughts of a press or a big drill press is the next option before drilling it out as laurie suggested. best wishes