A.I.R system Q's

[tomtom72]

I looked in my FSM (Helm) & I can't seem to find a mechanical description of the system's manifold parts and how they work. I 'think' that the metal tubes on the manifolds are just a way to get air into the exhaust stream and that any check valves are at the junction from which the small tubes branch out from? Am I correct in thinking that the object is to do a post lean out of combustion/exhaust mixture in "choked mode" on cold start up so the tail pipe emissions are cleaned up?

I observe this much: when my 90 is cold started I hear the AIR pump running for a short while and then it shuts off & I don't ever recall hearing it at any other time during me using the car. I would have to think that it shuts down way before the motor gets to "closed loop" operation; and that in "open loop" it only runs for a short time at cold start up?

I've been thinking that I can drill & tap pipe fittings into the header primaries & use comp fittings to connect the small tube to the check valve/manifold thing. Or make something using my plumbing experience....maybe, but it looks like it's brazing work & not solder work....yea I know a tig or such is the ticket but I don't have that equipment. I also realize that I'm a bit out where the busses don't run on this, but I need to either install this stuff on my headers & have it work....or I need to dummy it up so it looks like it works and hope I pass emissions inspection. Does anyone sell those small pipes from the check valve to the primary header tubes? I know I come up with the stupidest Q's. Oh yea, if I somehow get this AIR piping fabed up should I do it before I send the headers for coating or after they come back from the coating place?

TIA
Tom