The Stovebolt Site Forums The Shop Area The HiPo Shop Exhaust manifold fasteners material type?

Have been fighting the exhaust manifold bolts/nuts on my '38 Zephyr v12 flathead. Only been on there for 76 years. When I reinstall, I would like to put them back on with a reasonable chance that I or the next guy will be able to remove without making a sacrifice to some god. What type of fastener material would stand a good chance of coming off in the future without what I had to go through? I also plan to use a copper based anti-seize good to 1800 deg. Thanks

Brass is always a good choice for exhaust manifolds and flanges.

What truck is it going in?

Brass? Do you mean the actual manifold or the fasteners that holds it on?

I'd get some good quality grade 5 bolts and along with your anti-seize you should be in good shape, I would also use a good quality flat washer on each bolt. Re-tighten them after a few heat cycles.

I'm not sure what he was referring to, but brass will not be a good choice for either. Take don stocker's advice.

I've used brass nuts on exhaust manifold studs and exhaust flange bolts and studs on everything from farm tractors to sports cars for the last 50 years. Nothing comes off more reliably after decades of rust. Even use them on intake manifold and carb studs.

If you are talking about manifold to head Bolts, a good wipe of Never seize on the threads and any kind of bolt will come out years later.

The manifolds on a flathead are not attached to the heads. The only things attached to the heads are the hold down studs and the spark plugs. With that said, I will see if I can source brass nuts and bolts in 3/8x16. I wouldn't wish this job on my brother-in-law.
Before I do this....46gmcpu, why wouldn't brass work for this application? Thanks

Here are few posts that think that brass nuts are not bad: exhaust manifold to exhaust pipe

I have used brass and stainless steel nuts (with anti-sieze) - they are both better than steel nuts.

Another vote for brass or stainless w/anti-seize, preferably the copper based. Even better would be to install studs, rather than use bolts, with brass or stainless nuts.

Studs are great for everything. Carbs, manifolds or headers. Less chance of stripping the threads when installing nuts than a long bolt. Brass is good with a high copper content.

I now use stainless steel studs from Totally Stainless.

How much we're the studs about and did it come as a kit?

What year/size engine/exhaust-pipe?

Totally Stainless does not have an on-line catalog, but you can download it and look for the studs.

probably less than $7.00

Sweet thank you for the info

Brass can have a tendency to gall if not properly lubed. I would go with stainless, it's the modern improvement on fasteners and should last longer than you need them to.

Are we talking about the bolts/studs that hold the manifold to the engine or are we talking about the bolts/studs that mount the exhaust pipe to the manifold?

Just left the parts store with complete stainless sets for my headers and blower pulleys. Just need the stud kits for the dual carbs. I'm excited! Shiny makes you faster right?

Stainless will also gall if not properly lubed.

Brass is much more resistant to galling.

OK, here's the specs on the motor. 1938 Lincoln Zephyr V-12 flathead (the strangest motor I've ever worked on). The exhaust pipe diameter is 1-3/4". I am talking about both the bolts and studs that fit the manifold to the block (not heads) and what we would call the collector flange. There are 8 each 3/8-16x1" bolts holding each manifold to the block. There are two each 3/8-16X1-3/4" studs plus nuts that connect the so called collector to the exhaust pipes. There is also a cross over exhaust pipe, a heat exchanger for passenger heat and other stuff (I said it was strange).
I have not found all I need to go back with brass fasteners locally. I was looking through the "McMaster-Carr" catalog for the stuff. I was reading about the different tensile strengths and such and saw Silicon-Bronze. Has anyone have a history with this material around manifolds?
I have used SST in the past on my Chevy street rods but have to stay after them to make sure everything is tight. I really would like to find something that works, stays tight after a tighten up after a couple of heat cycles, and comes off, down the road, when I need it to. Thanks to all!

I like to use brass exhaust manifold nuts on standard steel studs. Real brass exhaust nuts are very tall. They cover all or most of the stud. Google for "Chevy brass exhaust manifold nuts" to see a picture. The problem is that most engines are 5/16 not 3/8. For bolts I use grade 8 steel, don't need the strength but much better steel, doesn't rust as badly and won't stretch in heat cycles. Since the threads in the block or head aren't out in the weather, a good coat of never seize will let them come out years from now with no fighting. Brass bolts wouldn't have the strength. Silicon Bronze is much harder and stronger, used a lot on salt water marine applications.

I never use stainless nuts on stainless bolts. Even covered with never seize there is a good chance of galling. Regular steel works fine because the bolt won't rust.

I use grade 8 on everything. All suspension, mounts, even the bolt that I attached to a chain to keep my engine from tearing the rubber mounts. Learned that lesson the hard way. And anti-seize is key.

Another virtue of brass is that it is easier to split off with a cold chisel when it does freeze to the stud or round off.

Use a good quality steel,stainless,or even silicon bronze, for the studs, bolts. You need the tensile strength. For the nuts you can use a good quality brass. Good luck finding that. Stainless nuts would be my choice with a good high temp anti seize on the threads. Make the nuts the sacrificial part and it should be good for many years. Studs and bolts are hard to remove when stuck. Nuts, not so bad. Never ever put manifold on with out anti-seize. EVER! As you can tell this has been covered pretty well. Brass and stainless will gall and the use of anti-seize will help that. Galled stainless is a b!@#h to remove. Galled stainless nut on a stainless bolt? A disaster. both will be destroyed.