Originally Posted by Civic2Scooby
as answered above, factory head bolts are what are known as tq to yeild bolts...meaning you are actually stretching the bolt inside the thread bore to make sure they are extremely snug. Once they are backed out they are useless and will snap off in the block if you try to re-use them.
Honda head bolts are not torque to yield and are reusable - i have been working on these cars for many, many years and have always reused the head bolts with no problems - if the bolts were torque to yield, they wouldn't have a torque value listed in the manuals - the following is from leading maker of TTY bolts:
"How to Identify an Engine with Torque-To-Yield Head Bolts?
Early TTY bolts were easy to identify by their undercut shank. Since then, many new TTY designs have been employed. Many of these do not use an undercut shank and therefore cannot be easily recognized as TTY. The most accurate method of determining a TTY engine is based on the head bolt tightening procedure outlined by the manufacturer. If the installation procedure requires tightening the bolt to an angle (vs. torque) specification, the engine requires new TTY head bolts. If torque values are used for tightening, new bolts are not required."