Hotrod lincoln
Actually Langdon specifically mentions the external tube idea on his web site and how it won't work.
Since this manifold would have the space of the heat channel between the tube and the floor of the intake passage, the heat transfer would be poor.
If I try the 2 exhaust connections and don't like it. I can always put the plugs back into the headers and connect the tubes to the cooling system.
That could wash the carbon out, or leave enough behind to seal the core plugs so they won't leak water.
