My stock 1980 has only one modification that I made to the setup, years back I replaced the thermal reactor with a 1981 exhaust manifold, while I remove the air pump and the other equipment that was no longer needed. Recently while I was stripping down the rats nest and following the post for stripping the Nikki carb, I removed the intake manifold to replace the gasket and plug the coolant connection to the intake manifold. The center ports for the intermediate housing has a rectangular opening below them. What are these for? I see on a 1981 series that the intake manifold is different and has a full gasket around the rectangle, I know that 1981 no longer had the thermal reactor, but on my1980 I can not find any information on this opening. And since I am the original owner, I do not recall ever having any connection to this opening. Attached is a picture of my setup.

thanks for input, I will look into blocking this opening, since I have been chasing an exhaust smell for a while. I just think that something must have been connected to this opening at some point but I no longer have the thermal reactor and other parts to verify this. I was thinking of using the plugged ports on the intake to hold a angled bracket against the opening and put a gasket to seal it.

So I was getting ready to block this opening, but I saw on YouTube a video on removing the intake manifold from a 1980 RX seven and this one still had the thermal reactor on the exhaust ports after viewing this video I saw the same opening was present when the intake manifold was removed. I beginning to think that this opening connects to nothing and the cutout was just planned for the next model year. Anyone have any thoughts on this?

thanks to Jeff 20B, I for sure have the thermoreactor ports on an angle. When I replaced the thermo reactor with the 1981exhaust manifold I did be sure that the gasket and manifold covered all of these holes.