With the torque to yield head bolts, is it possible to re-use them with a copper washer to keep the pressure needed? I'm about the swap off the GT-40P heads for a set of the X-turbo swirls and didn't know whether it would work. I know the safest route is to go with all new, but I just wanted to check first. I was told that when reusing the "torque to yield" bolts, they tend to stretch from the first use. However it is a crate motor that has only been turned over by hand since I received it. I don't know how much, if any, they would be stretched. Just checking to see if anyone else has had any problems with this before.....I don't wanna go and blow a head gasket and yank em back off to learn my lesson. Also.....in case anyone is wondering......engine is coming along nicely, finally got my 50 oz. balancer in after many months of anguish trying to find one locally that wasn't one piece with the serpentine pulley mounted on it. All gaskets on her with timing cover/oil pan/intake/etc. mounted. Before long, I may eventually get her painted and get the new floor pans welded in.
I have been told never to reuse them. Because once they are torqued down they have been stretched. And when reusing them you will not be able to torque them correctly. This is what I have been told. I have reused the 12 point head bolts before w/ no problem. Never had to deal with the 'torque to yield' ones.
I wouldn't reuse them, new bolts are a lot less expensive than the hassle of redoing the job. Here are a couple links to some info: http://www.autosite.com/garage/encyclop/ency01g.asp http://www.rolmfg.com/Technical/Answers/Stretch.htm
From Autosite The bolt replacement question is important. Ford says new ones must be installed any time they're loosened (one aftermarket company supplies them in the head gasket package), but the others either tell us to reuse the fasteners, or make no reference to the subject at all. Follow the recommendations for the engine at hand, or you could twist one off. From Oliver Rods: A: Don't confuse torque and angle with torque to yield. Torque to yield stretches the fastener past the point of where it will not return to its original length. This weakens the bolt and makes it unusable for repeated tightening. When you use the torque and angle method according to our directions, you will stretch the bolts to 75% of yield. This allows the bolts to be used repeatedly without fear of weakening them. Google search with way more info than needed. Google TTY search results.
