I think your rockers have been installed wrong in the shafts.
I would suggest taking all your rockers off the shafts.
Separate the intake rockers from the exhaust in piles.
Lay all the rockers on a bench on their sides.
Compare how close the valve end of the rocker is to the bench. You will be able to tell which are left and which are right hand.
If you look at Fig.16 on this
LINK you will be able to reinstall them in the correct position.
