Re-use Head Bolts?
Post Fiend
Joined: Feb 2008
Posts: 5,831
Likes: 121
From: St Albert, Alberta
So washing your head bolts off with brake clean drying them off and stuffing them back in the hole should be avoided. Also what is the first thing most of us do after cleaning metal bits ? Hose it down with a rust inhibitor to prevent corrosion, thus sealing it from the oxidizing effects of the oxygen in the atmosphere.
Like I said it is just a good practice. 99.9% of the time it would present no issues. But you know how Murphy's law works.....
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Mountain Pass
Joined: Oct 2016
Posts: 217
Likes: 2
From: the Mtns of Santa Cruz
They are not torque to yield bolts.
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.
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.
Post Fiend
Joined: Feb 2008
Posts: 5,831
Likes: 121
From: St Albert, Alberta
Yours are not narrower in the mid section it only looks that way. The top bit is to locate bolt in the cylinder head. And on the bottom since the threads were rolled it raises them up past the body of the bolt. If they were cut and not rolled they would be flush or narrower (Smaller Diam) than the body of the bolt.
And the bolts you seen with a much narrower shaft were likely torque to yield, so one time use.
Thread Starter
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Mountain Pass
Joined: Oct 2016
Posts: 217
Likes: 2
From: the Mtns of Santa Cruz
Yours are not narrower in the mid section it only looks that way. The top bit is to locate bolt in the cylinder head. And on the bottom since the threads were rolled it raises them up past the body of the bolt. If they were cut and not rolled they would be flush or narrower (Smaller Diam) than the body of the bolt.
And the bolts you seen with a much narrower shaft were likely torque to yield, so one time use.
And the bolts you seen with a much narrower shaft were likely torque to yield, so one time use.
Post Fiend
Joined: Feb 2008
Posts: 5,831
Likes: 121
From: St Albert, Alberta
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