Keep your heads peeled at V6 and the engine won’t go off!

Hello guys, I made the head seals with motor X30XE at my Sintra V6 year 97 and had the heads planned immediately. I cleaned everything cleanly as meticulously as possible and installed it again. Nockkenwellen incl. Hydros set again on the cylinders as they were. Despite that the camshafts (Nockswellen not yet turned to control time OT) are free, so I can’t open the motor with a valve. I then have the camshafts loose again I turn and block something and if I turn counterclockwise, which you can’t at all, then I come only half a turn. I think that the piston hits on the head.But the heads can’t be planned down when the valves are in there. I think!?!? But when planning, not much was taken off and the valves were also in there when planning. Isn’t there? The head is already lying up and the head seals the have been installed by Elring. Can anyone help me? THANK YOU THANK YOU!!! Greetings fideist