I removed the ACV block of plate on my 84SE (S5 manifold) and this round piece fell out from where the big hole is in the manifold. The kits that I've seen today do not have this. I probably bought this block off plate from rotary engineering back in 1989. Anyone know what it is? Filter? Is this part of the S5 manifold or something that came with the block off plate? In either case, I can't remember. I'm at work now but can send a pic later if needed.

 

Don't worry about the round thing. It should have been removed ages ago.