These are stretch bolts you have one initial torque and (2) 90 degree angle torques. Go by the specs dont double guess this. You always pull the 90 degree in order of the head bolt tightining specs and I always wait 10 minutes between each series of angle torques. Remember to lightly oil the threads on the bolts and I always install new ones when replacing head gasket. Make sure you clean the threads in the block good with carb or brake cleaner and have no liquids remaining in them before head installation.