A picture

 

that filter is for the distributor ,

follow the hose into the engine, and you will see it go to the distributor, there is another hose that goes to the air feed to the AAV behind the left air filter box , this is the pipe that sucks the air through the distributor from that filter

BB

 

What is the "AAV"?

 

which distributor the ignition or some sort of vacuum?

 

AAV = Auxiliary Air Valve. I think.

 

its a dizzy breather, end

 

Are these filters supposed to be changed?

 

I don't think it ever hurts to change a dirty filter :-) and given how cheap and easy they are to replace it's a no-brainer.

I didn't care for the way mine looked just hanging out inside the engine compartment, so I routed it forward and stuck a bit of hose on the other end. Makes things a bit neater, although you couldn't tell it by this picture.

Thanks,

John
1987 XJ-S V12, 62,000 miles