Just finished removing the broke in half exhaust manifold on the driver side on my F-350 SCS-390 and wanted to know what type of fastener you all use to replace the rusted stock bolts.I did a search here and found several ideas.
1-Stainless bolts and use antiseize when installing.
2-Use standard replacement grade 5 bolts and antiseize.
3-Use Grade 8 bolts with antiseize.
4-Use studs and nuts and antiseize,grade ?
5-Install stainless inserts in the head(usually when head is off)

I will machine the new manifold flat and use the felpro thin tin
heat sheild as my gasket.
Found a replacement manifold for $40.00 at
discountbodyparts.com.
My comments are -is stainless a softer metal than grade 5? Can SS
be drilled easy-outed in case of breakage?
-if grade 8 bolts are used and then later broke off,
will the be able to be drilled and easy-outed or
are they too hard to drill?
-I like the stud idea but don't know what grade I
would need to use.
What are some of your thoughts or ideas ?

"bowties in the rearview mirror"

 

Nod, what did you decide on, I will be replacing bolts as well.

 

The stainless steel is tough, but it is also brittle, meaning breakage is more likely. Its toughness would make it harder to drill out should it break. SS can also have galvanic reactions with other metals, namely other stainless surfaces and aluminum. This can mean that seized fasteners might be more likely, even guaranteed. Due to the heat and location of the manifolds, stainless steel is not needed. A good hardened carbon steel bolt will do well. Studs are better because they have more than one way to come off should one end seize. The best insurance against seizing is to remove the fasteners when everything is cold, and to soak 12 hours earlier with PB Blaster.

I just recently removed an exhaust manifold on a '97 4.0L, all fasteners came out easily and smoothly. I used the PB Blaster beforehand. Impact wrenches on lower torque settings can also be useful, impact tends to loosen things up without breaking stuff.

If you do use stainless, research the types of fasteners to use. Not all stainless is equal.

 

Thanks for the information. Do you know a source for manifold studs? I've checked the internet without much success, guess I could just try NAPA. I'm looking to fit a set of cast iron shorty headers on my 75 F-100 4X4 360, just want to get things right the first time. Thanks for the help!

 

Stay away from stainless for this application, too many reasons to list here. Go with black oxide/un-plated grade 8 bolts or studs for headers or manifold applications.

 

The dealer is probably going to be your best bet.

 

Thanks for all the info everyone.I decided on Old93junk's reccomendation and found exactly what I wanted at a local ACE Hardware store.Cost me about $18.00 for all new grade eight bolts and they had big flared heads so no washers were needed.
"bowties in the rearview mirror"