Well tonight I started putting on my head's and I was reading in the book and it said to torque them and then undo them and re torque them and then turn then 90 to 110 Degree's well I did that and so I desided to slowly adjust the torque wrench to just see how much touque that would be and I kinda figured it out to be 90 so why dont they just say 90 foot pounds ? All though I am going to do the same on the other head I was just wondering why Prolly sounds like a stupid ? but hey I would like to know if its at all possible ..
Thank You
Tim
(http://i18.photobucket.com/albums/b107/Dartman1074/CougarParking.jpg)
It's because the engine uses "Torque to yield" bolts, meaning that you are actually tigthening them to the point that they stretch - it's the point the bolt has the most holding power before breaking or stretching too much. That's why you can only use 'em once.
'Course, they may only be torque and angle, not torque-to-yield.
From http://www.oliver-rods.com/library/libraryindex.html
[COLOR="Red"]Q: Why use torque and angle?
A: We didn't invent this. It has been used by automobile and diesel manufacturers and in the aerospace industry for many years because it is much more accurate than using torque to tighten bolts. Torque and Angle uses the pitch of the threads as a good, repeatable reference for properly tightening the bolts. For example, if the bolt has a 7/16" 20 threads per inch pitch, then one full (360 degree) turn of the bolt will move the bolt exactly .050" (fifty thousandths of an inch), or 36 degrees of turn will move the bolt exactly .005" (5 thousandths of an inch). We have a specification for Torque and Angle for all of our bolts, no matter their size (5/16", 3/8", 7/16" etc.) and our specs are all derived from the pitch of the specific thread on each size of bolt.[/COLOR]