That's why I said "carbed" intakes... Offy or stock. If using an aftermarket TBI solution (such as a sniper on a 4 barrel Offy), you don't need this adapter as the EFI system will compensate for the IAT automatically. AFAIK the intake side is sealed... it's the exhaust side that can be open when the exhaust stove valve is opened by the bimetallic spring (which is why there's an exhaust-style gasket between the exhaust and intake).
1984 F150: 300 L6, AOD, RWD. EEC IV / TFI, Feedback Carter YFA Carb. Stock everything but radio (for now).