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

[Aurora40]

The check valves are those flared things where the pipes come out of the manifolds, they sort of "float" right on top of the manifolds. That's what keeps exhaust from travelling up the AIR tubing.

The AIR pump only runs at startup. I think 60 seconds on a cold start and 30 on hot? Might be 90 on cold start...

The purpose is to heat up the cats faster, because they don't work at all when cold. I believe the fresh air is to burn residual fuel in the exhaust, which will heat the cats up faster.

I don't believe the purpose is to "dilute" the exhaust, as that really doesn't clean anything up, it just makes it seem cleaner from a ppm standpoint.

I think if you were to add the tubes to headers, you'd at least want to add some stubs to them before getting them coated, otherwise you'd have to remove the coating from the area you are working on. I don't know, but I'd guess plumbing type attaching wouldn't work. Your exhaust, especially at the header, gets a heck of a lot hotter than any hot water pipe.

I'll try to get some pictures when I get home of how mine is set up, perhaps that will help in some way?

[tomtom72]

Bob thanks! Yea the way Mr H set yours up would be of great help to me. I'm trying to visualize something that I've not spent a lot of time looking at on my car. This weekend I intend to go eye up the OE install and maybe I can get some ideas from that too.

Thanks!
Tom

[zr1don]

I'm working on the same project, installing SW headers that don't have the AIR injection tubes (required to pass smog) please post your solutions as you progress. I am considering cutting the tubes off my stock manifolds & welding them to the SW's. Anyone have any experience/suggestions on this approach?

[Aurora40]

Pictures (though it's quite hard to see them, let alone photograph):

[RKC]

This seems to be a common problem for those of us with the visual smog inspection. I'm in CA. Just bought Uly's 1990 and took it into to smog. Didn't even get on the machine, the inspector said I had no AIR system and failed me.

I bought the SW headers but they haven't arrived yet. I think all the correct hoses are there, but those pictures should help with the hook up.

[tccrab]

Originally Posted by RKC

This seems to be a common problem for those of us with the visual smog inspection. I'm in CA. Just bought Uly's 1990 and took it into to smog. Didn't even get on the machine, the inspector said I had no AIR system and failed me.

I bought the SW headers but they haven't arrived yet. I think all the correct hoses are there, but those pictures should help with the hook up.

I'm not sure the SW headers have AIR fittings. I know that Marc Haibec sells modified headers with AIR fittings.

Be prepared for even more pain at the Smog shop.
SW's are not CARB approved.
In fact, nobody makes aftermarket headers that are CARB approved.
Callaway at one point made some, but they aren't that much better than stock and they are extremely difficult to come by. There is/was a set on FleaBay earlier this week.

There is only one way to go from here.
Get the SW's and have the AIR tubes installed if they are not.
Make sure that your cats are 50 state legal (some aren't).
Take it back to the Smog Nazis and tell them that you'll need to see a referee.
Go to the referee and tell him that:
A. The original cats failed.
B. GM does not make them anymore.
C. It's illegal to buy a used catalytic converter
D. The original exhaust manifold & cat converter is a single piece unit.

Be prepared to prove that GM don't make them anymore and has no inventory *anywhere*.

Good luck!!!

TomC
Fellow Californicatian

[RKC]

I believe the new SW headers that have been sold on the forum give the AIR tubes as an option. I went with the headers that place the cats before the y-pipe rather than the long tube headers.

Kind of a shame because I like the the sound of the long tube Watson's and Corsa exhaust. Can't compare the performance yet, but it seems common wisdom that long tubes breathe better on the top end than shorter headers.

Nevertheless, I am prepared to answer the questions about the headers. I hope it doesn't get as far as a referee.

[Aurora40]

I'm pretty sure it is EGR, not AIR, that is an option. If they have AIR, I have not seen a picture of it.

Watson's actually did have AIR hookups available. SW's are long-tubes, I don't see why they'd sound or perform any worse/different than your Watsons.

Also, sort of academic, but I thought longer tubes did better on the low end and shorter tubes were better up top?

[RKC]

I'm going to check with SW to make sure. Hope I'm right, otherwise it look like it's gonna cost more to get it right.

I did see a recent article somewhere in which AIR tubes were added to an L-98 or LT-1 motor. Probably best to have a pro do the welding with the proper equipment. Ther are definitely kits out there for regular small block headers. The dimensions might be close enough to make work. Also the check valves aren't cheap, but I don't think the LT-5 check valve is exclusive to the LT-5. Alot of years and different vehicles seem to use the same part number.