How exactly do I tell if I have air injection? I've heard from differnt companys about where its at, Banks told me it was on the passanger side, and Gibson told me it was on the driver side? Where is the flange at? I have a 91 F250 with a 460. Does anyone happen to have a pic of where it is?

 

Pump under alternator hooks to big pipes over passenger side valve cover on to catalytic converter. Pretty sure your truck had one, could have been removed. If you have to go through emissions inspection, gotta have it.

That is how it looks on my '91, could be a different configuration for a California truck or something, don't know.

 

So these go onto the CC? If I replaced my CC ever, how would these go back on?

 

The whole purpose of the air injection is to make the converter work. No converter, no need for air injection. If you buy a converter you can get one with the hookup for the air line(s).

 

you will have a 4 tubes on both sides, one going into each of the exhaust manifold pipes, they will be threaded in with some bolts, they are aobut 1/4" wide.

have fun

 

My 91 is not set up like this, the air goes to the converter. I have seen carburetted engines with the setup like you are talking about. Don't know for sure when they changed or if they changed back later.

 

The original 60's and 70's era air injection pumps dumped air into the exhaust ports. This was pre-catalytic converter, and getting the air where the exhaust was the hottest maximized the combusiton of HC and CO emissions.

The first catalysts did not have air pumped directly to them, but would assist in completing the reaction of the air-enriched stream coming down the exhaust pipe.

Later "monolythic" catalysts added the direct line to the air pump, giving rise to the "4 tube" system Mr. 87Carbed mentions.

When fuel injection was added, so were oxygen sensors. It is impossible to employ an oxygen sensor if air is being injected right at the port (as the mixture ratio is diluted by the injected air). So the air has to be pumped in downstream of the oxygen sensors and the injection at the port was eliminated. This is why you don't see the "4 tube" arrangement on fuel injected vehicles.

The more reliably stoichiometric mixture control afforded by feedback controlled fuel injection removed the need for additional burning as the exhaust exited the valve -- the catalyst can take care of the remaining emissions.