[Marshall V. Daut]

The best way to alleviate this very common problem is preventative: Install the manifold gland rings in the exhaust manifold BEFORE it starts sagging. Ford initially used these and then some time in 1929 he discontinued installing the rings, which resulted in manifolds no longer being counter-bored for the gland rings. Predictable warpage occurred in the #4 exhaust port, so Ford re-instituted installing the gland rings. He learned his lesson about drooping exhaust manifolds - and so should we. If you can't get your exhaust manifold to seal using the four gland rings, #4 is most certainly drooping. The only cure is a new exhaust manifold, copper manifold gaskets and GLAND RINGS. Otherwise, a drooping exhaust manifold and escaping exhaust fumes/noise are in your future.
Marshall