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Torque spec for fiero store exhaust manifold stud kit? by Travis D
Started on: 12-17-2017 02:45 PM
Replies: 10 (429 views)
Last post by: Spoon on 12-23-2017 11:34 PM
Travis D
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Report this Post12-17-2017 02:45 PM Click Here to See the Profile for Travis DSend a Private Message to Travis DEdit/Delete MessageReply w/QuoteDirect Link to This Post
And are you guys using anti-seize or any lube on these?
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Spoon
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Report this Post12-17-2017 07:07 PM Click Here to See the Profile for SpoonSend a Private Message to SpoonEdit/Delete MessageReply w/QuoteDirect Link to This Post
ANTI-SEIZE for sure on both ends of the stud. Torque spec... click link below. It may help.

https://www.fiero.nl/forum/Forum2/HTML/128069.html

Spoon

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Travis D
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Report this Post12-18-2017 12:25 AM Click Here to See the Profile for Travis DSend a Private Message to Travis DEdit/Delete MessageReply w/QuoteDirect Link to This Post
Thanks I'll go on the tighter end of the spec in that table. Should be alright.
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theogre
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Report this Post12-18-2017 10:23 PM Click Here to See the Profile for theogreClick Here to visit theogre's HomePageSend a Private Message to theogreEdit/Delete MessageReply w/QuoteDirect Link to This Post
OE Torque spec charts are Invalid w/ anti-seize or any other lube/sealer
Most are only for Clean Dry threads and when torque to spec with whatever then bolt/stud and threads are way overloaded and can break now or down the road w/o warning.
For rare exceptions you need to read full text or notes that goes w/ the charts but copy/past for internet is missing this data.
Example: Some head and other bolts need sealer because hits coolant/oil and often get less torque just for a bolt or three using this.

Worse when use studs and you bottom out the threads and torque too.
stud bottoming can cause big problems Results including stripped threads or crack heads/block because will cause stress in the head etc.

Bottoming out can be:
end of stud hits bottom of hole
Stud thread or unthread sections wedge into hole thread. Most blind bolt holes are not fully threaded neat/at bottom. Some studs bind/strip the top of hole when studs have unthreaded sections when torque before parts and nut are attach.
Worse Both happens.

So put studs in finger tight, if bottoms out back out 1-2 turns.
put all parts and nuts on finger tight then tighten w/ a wrench.

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Blacktree
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Report this Post12-18-2017 11:26 PM Click Here to See the Profile for BlacktreeClick Here to visit Blacktree's HomePageSend a Private Message to BlacktreeEdit/Delete MessageReply w/QuoteDirect Link to This Post
I'm with the Ogre on this one. The studs should be installed hand-tight. Plus the torque spec on the nuts needs to be reduced by about 30% if you use anti-seize compound. DO NOT put anti-seize compound on the face of the nut. Only put it on the threads.

The studs are not very thick. If you're careless, you can accidentally over-tighten them and snap them off in the head. That's what you were trying to avoid in the first place!
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viperine
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Report this Post12-19-2017 01:29 AM Click Here to See the Profile for viperineSend a Private Message to viperineEdit/Delete MessageReply w/QuoteDirect Link to This Post
Having done exhaust headers on small blocks, you're better off not being tight enough, and going back to re-torque after a few heat cycles. Even meeting torque specs seems to result in the eventual loose bolt/nut/stud. But going back and re-torquing is easier than drilling out the busted bits!
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2.5
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Report this Post12-22-2017 08:51 AM Click Here to See the Profile for 2.5Send a Private Message to 2.5Edit/Delete MessageReply w/QuoteDirect Link to This Post
Maybe one could use lock washers to help with any chance of loosening?
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theogre
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Report this Post12-22-2017 11:10 AM Click Here to See the Profile for theogreClick Here to visit theogre's HomePageSend a Private Message to theogreEdit/Delete MessageReply w/QuoteDirect Link to This Post
Could try but Most won't last long. many types Heat cycling changes hardness and any open areas heat and water = rust and fast.
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Blacktree
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Report this Post12-23-2017 09:59 AM Click Here to See the Profile for BlacktreeClick Here to visit Blacktree's HomePageSend a Private Message to BlacktreeEdit/Delete MessageReply w/QuoteDirect Link to This Post
Been there, done that. It doesn't take long for the lock washers to turn into flat washers.
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pmbrunelle
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Report this Post12-23-2017 06:38 PM Click Here to See the Profile for pmbrunelleSend a Private Message to pmbrunelleEdit/Delete MessageReply w/QuoteDirect Link to This Post
I wonder if lock washers of the star type would fare better for an exhaust manifold:
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Spoon
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Report this Post12-23-2017 11:34 PM Click Here to See the Profile for SpoonSend a Private Message to SpoonEdit/Delete MessageReply w/QuoteDirect Link to This Post
Chrysler slant six used concave washers on exhaust manifolds to prevent cracking. I guess they contracted and expanded with temp changes. I know they were pretty specific as to where to use them and where not to.




Spoon

[This message has been edited by Spoon (edited 12-23-2017).]

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