exhaust manifold studs bolts or what
September 16th, 2012, 07:57 PM
#1
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Location: Walton NY
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exhaust manifold studs bolts or what
Have a 350 that I need to put exhaust manifolds on. Don't have any studs or whatever is used. Seems as though it takes 3/8 coarse threaded bolts but the holes in the manifolds are much larger. Does a spacer go in there? Also I've seen where some say uses gaskets others say no. Thoughts??
September 17th, 2012, 08:40 AM
#3
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Location: Plano, TX
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Just 3/8" bolts. Don't use studs as it'd be impossible to work on with the engine in the car. I use grade 8, but that's not necessary.
Don't worry about the hole size difference. Also, don't use the top middle bolt. It just pulls the manifold on the top, frequently causing leaks on the bottom.
If you have pristine flat heads and manifolds, then you can just use a very thin coat of hi-temp silicone. Otherwise, you need a gasket. The cheap and cheery way is the FelPros. Easy to get, pretty cheap, but they can blow out. I just got a set of Percy gaskets (can get from Summit, etc) which are solid aluminum and supposedly lifetime/reusable gaskets.
Just remember to use anti-seize and re-torque the bolts several times after driving.
Don't worry about the hole size difference. Also, don't use the top middle bolt. It just pulls the manifold on the top, frequently causing leaks on the bottom.
If you have pristine flat heads and manifolds, then you can just use a very thin coat of hi-temp silicone. Otherwise, you need a gasket. The cheap and cheery way is the FelPros. Easy to get, pretty cheap, but they can blow out. I just got a set of Percy gaskets (can get from Summit, etc) which are solid aluminum and supposedly lifetime/reusable gaskets.
Just remember to use anti-seize and re-torque the bolts several times after driving.
September 17th, 2012, 08:49 AM
#4
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I'll do you one better, use 3/8-16 grade 8 bolts and put Ultra Copper on the threads before putting them in...2 birds, one stone
The Ultra Copper acts like anti-seize AND it locks the bolts in place until you're ready to pull them out...no re-torque necessary
The Ultra Copper acts like anti-seize AND it locks the bolts in place until you're ready to pull them out...no re-torque necessary
September 17th, 2012, 09:06 AM
#5
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Location: S.E. Louisiana, so far still in U.S.A.
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You've got a lot of good information. I'd like to emphasize the part about the anti-seize compound. There are several types available. Any will be an improvement. Some do better at high temperatures than others. If it was used at the initial assembly we could eliminate broken bolts in the heads. The next time they come off, the mechanic will thank you.
September 17th, 2012, 05:19 PM
#7
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9420462 is the p/n for the 3/8" bolt (9/16" head). List price is $3.58 each from GM.
3899696 is the p/n for the washer. List price is $12.50 per bag of 10. Or 1.25 each if your dealer will sell them to you that way.
413496 is p/n for the 3/8" exh. manifold bolts with a 5/16" stud made into the top end of them for G-bodies if you need that. But good luck finding any of those new. Rare as hen's teeth.
3899696 is the p/n for the washer. List price is $12.50 per bag of 10. Or 1.25 each if your dealer will sell them to you that way.
413496 is p/n for the 3/8" exh. manifold bolts with a 5/16" stud made into the top end of them for G-bodies if you need that. But good luck finding any of those new. Rare as hen's teeth.
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