I'll second what Larry said about how tight you have to torque the head bolts... Everytime I do this job while on the second 90 sequence I'm just sure I'm going to break something. Its really, really tight. Make sure you have a GOOD breaker bar at least 18 inches long - and make sure you are not tired because I can assure you when you finish the second 90 degree torque sequence you will be!!

Tim