Flathead manifolds

[Steve Passmore]

The lower channel for the carburetor is too narrow and exhaust whirls around in a chamber and therefor cannot balance engine flow. There is only one crossover pipe.
So tturley is right, why are they not offering crossover gaskets. 

No one said it was to balance the exhaust flow and they are both certainly not to balance exhaust when the exhaust has only one way to go.  No good looking up this generic stuff on the internet when dealing with Cadillac flatheads.       It would only be a balance if both banks of cylinders had their own exit pipe which the flathead does not but they are still crossover ports.   The lower one cross's exhaust gas from one side to the other to pre-head the inlet manifold and in Cadillacs words "To fully vaporize the fuel and be more fuel efficient"   I don't think you're doing your engine any favors by blocking this port off but that's your decision.  It doesn't matter. tturley was asking earlier if the entire exhaust manifold can be removed in one piece (which it can) which makes why they don't supply the top crossover gasket academic.  I presumed he thought there may have been a different gasket for the lower crossover ports rather than it being integral with the exhaust because that's the surface that is the point of this discussion.