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Intake manifold question
https://cimg6.ibsrv.net/gimg/www.rx7...c07a8c61f4.jpg 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. |
It's open to exhaust. All 1979/1980 where like this. It makes for an annoying exhaust leak.
Here is my 1979 https://cimg8.ibsrv.net/gimg/www.rx7...dd78407a98.jpg |
Pack that port with quicksteel or JB weld's Steel Stick
Use about 1/3 of the tube or so. Also make sure the port is clean as it is usually lined with carbon and a little bit of oil as it is in direct communication with the exhaust ports. On yours maybe don't worry about it if it has always been open. |
Thanks for input
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. |
Still not sure about opening
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? |
That is correct.
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So is there no internal connection?
So there was never an internal connection to exhaust ports on a 1980 engine?
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Only on certain models. Mazda was jumping through a lot of hoops back then to meet CA emissions requirements before they went with a cat system for 81 and later. The easy way to determine this is if your rotor housings have the thermal reactor-only ports that the 81 and later ones lacked. These ports are drilled at a steep angle.
A quick rule of thumb is if your housings have these steeply drilled ports, you are most likely not going to have a connection with the ACV port in your intermediate plate. That means you will not need to worry about filling it with quicksteel. |
Very good information
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. |
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