ok, so i removed my valve covers and am trying to remove the head so I have to remove those lug bolts (not idea what they are really called) that stick out to hold the valve cover on. 3 came out with a bit of persuasion but one is stuck. I tried putting 2 nuts on it and tightened them down so i could try to unscrew the bottom one and therefore unscrewing the post but it is so stuck it just started cross treading the bolt. Anyone have any ideas? I don't have a welder and I don't want to get any metal shaving inside my engine. Also when I do break this bolt (Cuz I know i probably will) where do i get another one? My searches have not brought any up.

Thanks!