Hi folks-hope everybody’s having a good week so far.

I am pretty rusty because I’ve been focused on other stuff. Question here – I am looking for confirmation on whether I need a spring washer. I’m using these copper nuts to attach the headers to the engine.

I believe so but wasn’t sure if there’s anything special about that design of the copper ones that make that unnecessary.

Thanks!

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So funny you note "rusty" and that's the idea why the copper nuts are used.

I used to put stainless spring washers with those. They keep snug the torque when hot which is pretty low.

So yes I would.

As I recall, the short answer is NO. IIRC they freeze to the studs and cause all kinds of

There ya go....two different opinions.

Do or not do...there is no try.

I could write a white paper on why but.....that wouldn't be short

Is that the ‘oval’ variety? Hard to be sure from the picture. Steel under the copper finish.

Just went through this.
DO NOT use the oval copper nuts. DO NOT use the nuts with the lock ring on the top. You can't remove them without pulling the studs out of the engine case.

If you can find copper flange nuts without the locking features, use them. Otherwise use steel and put milk of magnesia on the stud.

Zach

That's something I learned from Jake a long time ago. It has worked well so far!

Wow - thanks gentlemen, glad I asked.

Really appreciate the advice.

Those are called “prevailing torque” nuts that will usually cause the exhaust stud to back out. You need plain flange nuts. You can run a M8 x 1.25 tap through the copper coated nuts and they won’t pull the studs.

Thank you

There is an M8x1.25 Mercedes Benz exhaust manifold nut that works well and has a coating that keeps it from seizing to the studs.

I don't know the part number for it, I buy them through Zims.

@partsguy22 ... Aaron, do you have a picture of them?

In my defense, I did check PET first but it isn’t clear if these nuts (regardless of metal vs copper) need a lock washer as well.

I would assume they do but wanted to ask.

Thanks!

Lock washers are useless at locking anything (don’t make me post the NASA document).

Flange nut is the way to go.

There may be some confusion about the term copper nut. There are copper coated nuts and nuts made from copper. Two different animals.

Well who am I to argue with NASA.

Thanks!