Do you have the correct bolts? They are supposed to have an anti-rotation feature: either a flat on the side, or a strange shape with fins sticking out the sides. If you have the wrong bolts, you'd get what you are getting. If that's the problem, the solution is to remove them (Vicegrips on the head, for example), then replace them with the correct ones.
I'd really like to see a pic of a 4 cylinder Victa push mower. Sounds like the previous owner was Tim the Tooman.
