318-3 Closed Chamber Truck Heads

This is indeed into the water jacket. Ma did the same thing on some heavy RB engines

This is a photo of an RB just as an example. These are the ones used the "high mount" oddball water pump with the water ports on fronts of the heads. Notice the temp sender LMAO. Notice the odd canted plugs, which are "Ferd style" 18mm

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