f150harleytruck7

i have a d16z6 motor, and i had a valve job and resurfacng done on the head, i torqued it down on the block, and started installing the valve train, i used factory torque spec to bolt on the rocker arms in sequence, set my wrench, and snapped a bolt before it clicked, i got it out the head but i dot want to keep doing this, any suggestions, maybe u have to intall the rockers before torqing the head down? i do have problems aligning the dowel pins, any help would be greatly appreciated thanks