Manifold Question

[Taylormade]

Although my car, a 1932 Dodge Brothers DL (six) did not have them, I have seen exhaust nuts that are brass used on the studs to bolt up the manifold.  I bought a kit for my 1948 Plymouth P-15, which has a similar engine, from Vintage Power Wagons and they were brass.  What is the purpose of the brass nuts?  Does it have something to do with expansion rates so the nuts don't crack the manifold when it heats up and expands?  Is it worth it to find brass nuts and use them?

 

On a similar note, anyone have any experience with having your manifold coated?  I've seen hi-temp powdercoating, hi-temp paint and porcelain advertised.  Any experiences, good or bad, with any of these?

Thanks.

[ply33]

Brass nuts won't weld themselves to the studs and if they do they will strip rather than damage the studs when they come off.

[Rusty_OToole]

Right. Even if the end of the stud is rusty you can blow the brass nuts off with a torch, wire brush the stud and it is good as new. If you always use the correct brass nuts you never need to replace the studs.

 

But, mechanics use steel nuts with no thought of the future so at some point Chrysler switched to nuts and bolts which are a cinch to replace.

[Joseph P. Indusi]

Eastwood high temperature manifold spray can in cast iron gray color is very good and lasts for years.

I tried brass nuts on manifold studs for a straight eight Buick but could not get the correct torque because the brass was too soft and stripped the thread on the nuts. I went to grade 5 steel and have had good luck.

Joe

[JACK M]

I usually use brass nut on exhaust, they are easier to get off later.

As for the coating, I have never found any paint that will hold up on exhaust. Ceramic coating is the way to go.

I had a pair of manifolds done about 20 years ago and they still look great.

There are different qualities of ceramic coating, the mail order places seem to be less quality.

There is a place in Portland (maybe Milwaukie) OR called 'RMS engineering' that does very nice work.

You get what you pay for I guess.