Weird sound from engine bay
 

https://cimg8.ibsrv.net/gimg/www.rx7...76c1b9fdf1.jpg
https://cimg1.ibsrv.net/gimg/www.rx7...c7029707ce.jpgI know this one goes like this i just dont know how the spring and the other piece goes


I've checked everything and I think this has to be the problem, the car is a 79 SA with the original 12a and the nikki. The car has been having a weird sound that I would assume is an exhaust leak but I checked everything and it was tight. My grandpa said that this might be the problem though. What even are those used for?

There's supposed to be a diaphragm in there. That's where the air control valve goes, being secured with three 10mm nuts. I'll have to pull the ACV off of one of my early SA intake manifolds and see if the slotted piece is supposed to have any rubber on it. I don't see why it would be open and slotted rather than have a diaphragm in its place.

Can-shaped thing goes in first as you have it in the bottom picture, then the spring, then the round metal cap with the dome facing OUT. Then the ACV (Air Control Valve) gasket (which is really thick, about 3/8", and acts as a seat for the dome on the cover) and the ACV itself goes over it all, holding the spring in place. The ACV has a number of diaphragm valves and hoses that go to it.

It's the check valve for the air induction system, part of the emissions controls for pre-catalyst cars. There's a really crappy photo of it on page 1A:2 of the '80 FSM (figure 1A-8). '79 was identical.

ok thank you ill check it out:nod:

So i checked everything and i think ive figured out what the problem was i think

https://cimg9.ibsrv.net/gimg/www.rx7...b85fe44d29.jpg

https://cimg0.ibsrv.net/gimg/www.rx7...ebee5f7678.jpg

Is this square hole supposed to get covered by the manifold??

https://cimg1.ibsrv.net/gimg/www.rx7...6b058d30a2.jpg

because i checked it and it isnt big enough to cover that hole TBH

Check out this thread. I just posted my similar experience with my all stock early 1979. I just ordered a 1981-1985 intake gasket and will enlarge the gasket port size.

https://www.rx7club.com/1st-generati...1104049/page2/

would that cause an exhaust leak?

I don't know why, but the stock intake just blocks that square port. The 1979 gasket I ordered from Rock Auto, as shown in my pic in that thread, would cause the port to not be sealed creating an exhaust leak. With the 1981-1985 gasket, the intake will seal.

I hope someone else can chime in on what is going on and maybe the correct gasket to use. When I got my car it had sat for 20 years and the gasket was dust.

I have the factory part manual and it shows a gasket that does not even incorporate the square exhaust port.

If your referring to the gasket in my pic, yes, that one will not work. Here is the one I ordered. I'll enlarge the center ports on the gasket to match the irons/intake.


https://cimg3.ibsrv.net/gimg/www.rx7...c3554ab5a8.jpg

81-85 12A Rx7 Lower Intake Manifold Gasket (1881-13-111B)