[Bob Bidonde]

Drop of the exhaust manifold occurs from the weight of the muffler assembly repeatedly pulling downward on a very hot exhaust manifold. The thick conical washers under the manifold attachment nuts allow the manifold and studs to expand when hot, so overly to tightening the nuts flattens the washers and defeats their purpose. The gland rings protect the copper type manifold gaskets, but are not necessary if the gasket is steel.