It's unlikely you damaged the valves by hand. To be safe when turning the camshaft, place the crankshaft about 1/8 turn before top dead center. That will insure no pistons are all the way up where they could hit a valve. Once the cam is lined up, then bring the crank to top dead center. And install the belt.
If I understand your concern about the cam sprocket being off by 180 degrees, it will be every other crankshaft revolution because its sprocket has exactly twice as many teeth. Just turn the crank one more revolution, (always in the normal direction), and the cam sprocket will be lined up.
Saturday, December 15th, 2012 AT 2:04 AM