Cannot rotate my engine

My original problem was a cylinder misfire in my #1 cylinder which I troubleshot to an exhaust valve that was leaking. I replaced the exhaust valve put everything back together the first time thought I put the timing back the way it was, but I must have messed up somewhere and the car would not start since the timing was off. So I decided to take it all off again and just reset my timing and I took of the front cover and when I try to rotate my engine to alight the timing it will not turn any direction at all. I do not want to try and force it any direction since I do not want to break anything. I was rotating the engine just fine just before I took the front cover off.

At first I thought it must be interfering with the valves, but I disconnected the little arms in between the camshafts and the valves so that the valves are all closed and stay closed and the camshafts spin freely. All of the spark plugs are taken out as well and my car is in park. I really have no idea what else it could be.