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So... my Cyl Head bolts came out relatively clean (trq spec is 130-140 lbs!) even though I needed a hefty extension bar on a 1" drive to ease them loose
and upon closer inspection, noticed that they are designated with an "F" on the bolt head.
Thought I'd do a bit of investigation on this designation... and zip. Identifiers like these are often used to designate the fastener mfgr... but I couldn't find any reference for "F" ... even in this COMPREHENSIVE pdf published by the Illinois Department of Trans. :
I wonder if the F is for Ford... and they manufactured their own Head Bolts
Thoughts?
Also... anyone familiar with a "law" of never re-use high torque bolts? I'm prepared to clean up the threads (on both ends) lube them up good and re-use 'em.
So... my Cyl Head bolts came out relatively clean (trq spec is 130-140 lbs!) even though I needed a hefty extension bar on a 1" drive to ease them loose
and upon closer inspection, noticed that they are designated with an "F" on the bolt head.
Thought I'd do a bit of investigation on this designation... and zip. Identifiers like these are often used to designate the fastener mfgr... but I couldn't find any reference for "F" ... even in this COMPREHENSIVE pdf published by the Illinois Department of Trans. :
I wonder if the F is for Ford... and they manufactured their own Head Bolts
Thoughts?
Also... anyone familiar with a "law" of never re-use high torque bolts? I'm prepared to clean up the threads (on both ends) lube them up good and re-use 'em.
More thoughts?
F Marked are generally Ford Manufactured Remember back in the day Old Henry had raw materials go in and cars go out.
You can reuse the head bolts. These are not torque to yeild so they can be reused.
... thx Matt... so my hunch was right. Go Henry ;-)
When you get some time, do a little researching about Henry Ford. You'll find that He controlled every aspect of manufacture. From forests for wood right down to inventing charcoal as to not waste a by-product. I've spent 30+ years researching him and still feel as if I've only scratched the surface.
I always used to run all my head bolts through a die but I think I read later that is a big no no...
Yes a big no no. The threads on heads bolts are not cut but rolled this does not interrupt the grain of the steel and reduces stress risers in the valley of the thread..
Thread chasers can safely be used to clean and restore existing threads on bolts and in threaded holes because they do not cut, but taps and dies should only be used to cut new threads...not to repair existing threads.
thx Gents! VERY much appreciate the tips.... especially re "NO Dies!" I was totally going to do that. I'll use Dave's method and run a wire wheel over the threads (gently)
... or... order new. Thx for the links, Jim... don't envy the job you had to do removing that stud! ;-O
You can usually tell if bolts are torque to yield by the torquing method.
Torque to yield bolt are generally torqued to a certain value then tightened X numbers of degrees. Torque to yield bolts are torqued to elasticity then tightened by x number of degrees in to plastic deformation. This permanently deforms the bolt by lengthening it as it has been stretched past elasticity. They are one time use fasteners.
Sometimes they can be identified by having a section on the body thinner than the locating shoulder and the threads. This thinner area is the part that will stretch to plastic deformation.
If you feel the need the replace then get them from a reputable supplier, ARP for example, avoid getting ones of questionable Chinese manufacture where you'd probably be better off re-using the originals.
I have never had a Ford head bolt fail in reuse, it is a rare occurrence for this to happen.
Just inspect them and clean them up. If any show any signs of corrosion in the threads (pitting) replace it. Also avoid using chlorinated brake clean to clean them up.
Chlorinated solvents, chlorine is a corrosive oxidizer it attacks metal on the molecular level due to ion exchange and can on occasion lead to pit induced stress fracturing.
This is a big problem on Stainless and applications that are in a low free oxygen environment (bolts in a blind hole for example).
You should never use chlorinated solvents on stainless fasteners. There have been 2 cases roof collapses in public pools due to due to chlorine induced stress fracturing of stainless support rods. Mind you this is a pool that see continuous exposure but in a oxygen free environment the same forces can be at work.
Just avoid using Chlorinated brake clean on critical fasteners going in to blind hole, this more of a good practice than a hard and fast rule.
avoid using Chlorinated brake clean on critical fasteners going in to blind hole, this more of a good practice than a hard and fast rule.
Good info, thanks for the reply. Does this still apply if completely dry, or is it only an issue if the bolt was installed while still wet with brake cleaner?
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