CTCI Authenticity Chairman
Most cracked or broken ears on exhaust manifolds are caused by the use of gaskets between the manifold and Engine. Exhaust manifold gaskets were never installed at the factory and were never offered as a service part by Ford Motor Co. They were designed and manufactured by gasket companies and sold by major Parts suppliers.
The exhaust manifolds were designed to be machine fit, metal to metal. They can be checked for flatness with a long board and sand paper. If a correction needs to be made they can be re- surfaced by any good machine shop.
The reason gaskets should not be used is they tend to shrink and leak. When they leak the natural tendency is to tighten the bolts. Later they leak again, the bolts are again re-tightened, and after a few times the end of the gasket compresses enough to crack or break the ear on the manifold.