Let's Talk Turkey --- Head Bolts 'n Stuff

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Grumpy AuContraire wrote:


Many engine designs have used a torque-to-yield design where the bolt actually is stretched when being installed and will not return to it's original dimensions when removed. I don't know if your Honda used such a design or not, but if I were rebuilding one I sure would find out!
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John Horner wrote:

all you do is compare bolts for thread elongation. not hard.
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Hey Grumpy, you sure started a pretty long thread!
Most of it is correct, and your replies show you are on the right track too.
-Yes, they say those bolts are only one use, but I have re-used them in D-15 motors with NO problems. IF you have a problem it will be when the threaded portion breaks off on the final torque. If that should happen, your $16 ea will be well spent.
Run a tap into each of those head bolt holes. I've pulled out LOTS of crap from the bottom of a hole that would have screwed up torque values.
Engine oil on threads?? Forget it! I saw an interesting demonstration by an ARP guy torqueing fasteners with oil and assembly lube. The oiled one creaked as it was torqued. The other one was quiet, and torqued smoothly. ARP assembly lube is $15 for a tube but it will last a long time. I also use nev-r-seize too, and it works well.
I would worry more about the rod bolts. THESE are the ones that snap when re-used and should be checked carefully.
-SP
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Speedy Pete wrote:

no they're not.

unsurprisingly!
torque to yield bolts don't work like that. you'd have to go /way/ over yield to shear these bolts.
torque to yield bolts are typically loaded to 98% of yield, not 90% like a normal bolt. the remaining 2%+ to actually yield them occurs on first warmup and the resultant thermal expansion. yield does typically /not/ occur during actual bolt tightening.

you can use whatever you want to lube on reassembly, BUT IF NOT USING THE LUBE IT SAYS IN THE BOOK, YOU NEED TO USE A DIFFERENT TORQUE VALUE. if you want to use book torque, you use book lube.

where do you work speedy?
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