Could someone tell me what exhaust manifold gland rings are? I'm guessing they might bridge the gap between manifold and block. My engine doesn't have any such thing.
The exhaust ports in the block have counterbores several thousands deep on the manifold side. There is a corresponding counterbore machined into each arm of the exhaust manifolds. For most of production Ford supplied steel rings that fit into the two these counterbores and bridged the gap. These glands serve two purposes: they align the manifold openings exactly to the block openings, and they center the gaskets to these openings. They also shield the gasket from direct contact with exhaust gases.
Over time, especially if the glands are not used, the rear of the exhaust manifold (especially #3 and #4) sags. If that is the case, you cannot use the glands since the four holes in the manifold no longer are in a line. Eventually you will get to the point that the sag is so severe that you cannot seal #4, and it will leak. I have removed a manifold that had a 1/2” sag at #4 compared with the line of #1 and #2. When you get to that point your only option is a replacement manifold.
There are quite a few folks who feel that the glands are not necessary, that they just complicate things. You can search and find plenty of discussions on this in the Barn. If your manifold is good or new, gland rings may help slow down the sag. A caveat is that when you deck the manifold sealing surface of the block, or deck the two manifolds together, you need to check the depths of the counterbores and make sure you won’t bottom out on the gland rings when you tighten. I do this by dry fitting the manifold with the gland rings but without gasket, if it sits flat then I’m good to go.
BTW, in terms of manifold gaskets, I’ve had the best luck with the two-piece copper sandwich gaskets used in late ‘31.
