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Head Bolts and TTY - A Discussion

02/09/2008


What is so special about our torque to yield head bolts? Aren't there any others that could work if used with washers/spacers or cut off shorter or something?

Just wondering.

Best Regards,
Doug
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Unfortunately someday our cars may come to this.... Especially if the aftermarket doesn't step up for head bolts, (studs) head gaskets and the like. Assuming re-usability is confirmed as not a reliable option (like Eric is trying now).

I haven't queried a count lately but when I bought my Left bank head gasket there were 44 left in the ford system, and bolts were getting hard to come by as well, consider that every head job requires 10....

I wonder if the aftermarket has caught on that they could sell head gaskets for $100 each and have thrilled repeat customers.... There are few vehicles out there that can command that price for head gaskets, however we are not a large market...

Scott
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Uhmmm.......we've got all the head bolts. Yeah, all of them.


Doug Lewis
Ford Performance Specialists Inc.
Atlanta Georgia (770) 949-7191
*Shame less plug!*U.L.
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To my understanding it's a stress fracture thingy. Aluminum is a very
thermally dynamic metal - i.e. it swells and shrinks a lot compared to
steel when its temperature changes.
The head bolts need to have a spring like quality to track back and
forth with this movement at every heat cycle. Too much or too little
force is going to cause head gasket problems. An exact stress match is
pretty important.
I contacted ARP fasteners a few times and they have no interest in
playing with our low production motors.

Once a TTY bolt is set, it is stretched ever so slightly into its
"flex" range where it stretches back and forth happily. When this
stretch is de-stressed, the head rebounds back and in doing so is said
to form stress cracks in the bolt in the stretched section.
Re-stretching a used head bolt runs the risk of bolt failure due to
traveling stress risers eventually breaking the bolt, so they say.

This is exactly the experiment I'm running on my recently repaired
Ebony 97 cam failure. You see, sometimes, bullshit is bullshit and
SOMEBODY has to test the waters. Call me back in a year or so and I'll
tell you if I was right or not. In the meantime, go ahead, read the
rebuild manual, it says you MUST replace the head bolt WASHERS too.

Puh-LEEZE!. TTY Washers?
I'm willing to risk a hunch at this point. Sure would be nice not to
HAVE to replace everything whenever I crack a head off yet another
camfailed car.

Eric Lehmann
97 Ebony 42k Welded - With the Angels Now so that I don't have to be.
Long Live the Garage Queen !
97 Ebony 182k Resurrected, Welded, Experiment in progress
96 Medium Willow Green Metallic 103k Resurrected, Welded, Eaton M90 inside
96 Rosemist 72k 2006 Best Of SHO, Popular Vote, 2007 Best Gen 3, Welded
96 Medium Graphite 120k - Resurrected, Welded
97 Pacific Green - Parting this one Out
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I am all with your experiment Eric, and will be anxious to know the results.

I am with you on the concept of TTY washers - I'll reuse the washers without any bad feelings. It would be different if they were $0.15 each or something but they were about $2 each and buying $20 in washers per head seems pretty pointless to me when the ones that were removed were still flat as a pancake and not even scarred up.

Scott
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http://www.taurusclub.com/forum/index.php?showtopic=55275

http://www.taurusclub.com/forum/index.php?showtopic=55275
Cliff's notes: Duratec head bolts don't fit; they're too long.

--
Daniel J. Holtman
Props to TCCA for having that information, reproduced with I hope their permission!

U.L.
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It's my guess now that, as Doug said, it's not bottoming out per say, but running out of threads. I'm interested in opinions on whether it would be a good idea to thread the bolt higher up.

The ridge in the center of the bolt is a washer keeper - keeps the bolt and washer together so that you HAVE to replace the washer with the bolt. FYI the SHO washer has a slightly larger inner diameter so it fits over the keeper ridge and would work as a shim.

Yes, that is a 3.0L Duratec bolt. According to Autozone.com, the 2.5L Duratec uses the same head bolts.

Daniel J. Holtman


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