I need to make a replacement one of these thick washers that is used under the inverted acorn nuts at each end on the exhasut manifolds. The article on this says brass but the one I have left looks to be too hard for brass and I am guessing it is a bronze.... yes? no? What alloy? Anyone know?

Tnx in advance...Mark B.

I would not over think this,,,

get the thickness close and torque right and unless you are working for a 100 point Concours award,, you will be fine

Well, I am not trying to do that LOL. I ask because I already tried a soft/medium brass (I cut down and reshaped a brass exhaust nut) and when I toqued it to 10 ft-lbs, it was soft enough to 'moosh' a bit into the hole in the exhaust manifold. Not much, but enough to create an edge against which the manifold might not be albe to move. So, that brass was just too soft. My one original washer doesn't 'moosh' under 10 ft-lbs of torque.

I didn't think those two end nuts were brass on our '74, '75, '76 engines. I just used (aircraft) castle nuts, the kind used with cotter pins, and installed them upside down. The taper in the special washer puts the squeeze on the "castles' to lock them. I did use anti-seize on the threads to help with later gasket changes. That's my story and I'm stickin' to it, but with anti-seize. P

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"Louise", a 1976 Dart Custom project, (now sadly reverted to being just an "organ donor" to our other project Darts.)

Tnx. It is not the nuts but the washer material I am trying to figure out.

I am by no means an expert, but I would assume the flat part of the washer against the head would still allow enough movement, even though the washer is "mooshed" into the manifold a bit. Is this assumption wrong?
If you are not sure and don't want to risk it, I am sure I have a couple of those washers if you want them. They are used but should do the job.