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exhaust header bolts

 
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rdssdi



Joined: 17 Dec 2008
Posts: 58

PostPosted: Tue May 31, 2011 8:04 am    Post subject: exhaust header bolts Reply with quote

What type of bolts should I use to attach headers to a crossflow?

Grade 8 OK? Something that will be easier to remove once used.

Bob
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peteleo



Joined: 24 Aug 2008
Posts: 897
Location: San Mateo,California

PostPosted: Tue May 31, 2011 11:18 am    Post subject: Reply with quote

Bob,

Grade 2 ( low carbon steel ) bolts are sufficient. Attach 2 studs on both ends of the cyl head to make it easier to line up the manifold. Install 1/8" flat washers for the bolts and nuts ( adding lock washers is worthless as they weaken by heat ) then use thread-magic anti-seize and torque them to 15-18 ft lbs. You will need to re-torque after +100 miles.

Grade 8 bolts are usually used for high torque appl. i.e. torque converter and flywheel bolts. Grade 5 for cyl. head bolts.

Pete
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robarc



Joined: 17 Sep 2008
Posts: 41
Location: Bumpass Virginia

PostPosted: Thu Jun 02, 2011 7:23 am    Post subject: Reply with quote

Actually grade 8 bolts anywhere in an exhaust system are a bad idea, the heat affects them in a bad way. They become very brittle and will break off on their own or when you decide to try to remove them. It is a phenomenom called hydrogen enbrittlement (I think). And yes I have tried this and failed.....
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Rob
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