Looked under the Eagle, got a surprise

[captspillane]

For clarity sake, we need to agree on some terminology.  I use the terms "Air-pump" or "Pulse-air."  Specifically I mean “Air Injection Pump” when I write “Air Pump.” For those who are not familiar, many AMC motors had an air pump powered by a V belt that put positive pressure directly to a vacuum controlled valve. When that valve opened, it injected air directly into the exhaust manifold. Air Injection pumps were found to cause detonation problems and could cause damage to the engine. It was replaced in both Jeeps and AMC cars by the “Pulse-air” system around 1983. That was a series of check valves and vacuum actuated solenoids that injected air directly into the side of the catalytic converter. The term “Air-pump” can also refer to a glorified electric fan hooked up to the injection line on the side of the catalytic converter. That’s common to other types of cars and trucks, but was never installed in any AMC or Jeep vehicles.

Some early Eagles still had bolts plugging the hole where the injection line was designed to attach. By 1983 the casting had changed and a flat spot replaced the holes in the exhaust manifold. None of my ’80 to ’83 Eagles had an Air Pump when I got them, so I believe that Eagles never had them. All the Spirits I’ve encountered did and several of my CJ7’s did. The AMC Eagle was classified as a light truck, so it had some subtle differences in emissions requirements from the Spirit. It was the light truck classification that let the Iron Duke Eagle motors go without any air pump system while the passenger car classified Spirits needed an air pump with the Iron Duke (thats also why Spirits have those hideous front bumper mounts and Eagles do not).

For PA state inspection on my Spirit I used an electric Air Pump from a Chevy S10, circa 1995. That went through a check valve to the side of the catalytic converter. Since the systems all accomplish the same goal of making the catalytic converter more efficient, they are all interchangeable legally. These systems also can be eliminated legally when you convert to fuel injection, since you are updating your emissions system to newer standards and equipment.

[captspillane]

Carnuck is saying that if you use a universal catalytic converter with an Air Injection Pump equipped 258, the air being forced into the exhaust manifold will heat up the catalytic converter too aggressively and burn it up. That sounds like something he has learned from experience.

He is not saying that hooking up a catalytic-converter-direct electric air pump or Pulse-Air system to the side of a universal catalytic converter will damage it. I objected to his statements before because I didn't understand what type of air pump he meant. The person who started this thread and most of the people on this site have a Pulse-Air system on their cars and do not need to worry about Air Pump systems.

I still don't know exactly what he meant by this statement, "That's because aftermarket cats are required to have the tube to be able to hook up to the original AIR for looks and not function. Cap off an OEM one and the car's floor will get VERY warm in a hurry if the internals are still in it."

An Air pump only hooks up to the exhaust manifold, it doesn't hook up in any way to the cat. Also the car in question has a pulse-air system, so "origninal AIR" I took to mean pulse-air  system. Capping off a OEM injection tube limits the air that gets in, so it doesn't heat it up as much. "Aftermarket Cats" must mean universal catalytic converters that come with the injection tube on the side already capped off to be used with or without it. That injection tube is not decorational, its functional.

[carnuck]

CA models got both AIR and air pulse systems. I see a lot of them here in WA. I'll snag a pic of mine next time the hood is up and before I rip it out!

[captspillane]

What year is your Eagle? My '78 and 79' CJ7 is Air Inj. Pump, and my '84 CJ7 is Pulse-air. Somewhere in '81 or '82 they stopped putting Air Pumps on any AMC 258's. There might be a bunch of '80 and '81 CA Eagles with them. I've never seen one in a PA junk yard. Thats probably a great question to ask GRONK. He's been under the hood of more AMC cars and Jeeps than anyone with those M2150 conversions.

With your experience with them, I bet you second my advice to ditch the Air Pump immediately. Besides the potential of engine and presumably catalytic converter damage, its a maintenance nightmare on a 30-year old car. The little tubes are impossible to unthread from the exhaust manifolds. Your picture will show a rat's nest of tube and lines and stupid junk all over the top of the engine. Its a great reason to go to throttle body or muli-port injection besides the power, efficiency, and starting reliability.

I'm curious if any Grand Wagoneer owners are familiar if they kept the Air Pumps on the AMC 360 until their end of production (1991?). I've never seen a V8 with a pulse-air system but I've also never owned a full-size Jeep. It won't matter if you convert an Iron Duke Eagle or if you use a Howell TBI kit with your AMC V8. There's even a crazy expensive MPI kit available.

[vangremlin]

My 81 with a 258 has an air pump.  I still have all the components bolted on, but somehow the belt never got put back on the pump when I swapped engines.  I'll have to add that to my "to do" list one of these days.

[Zoro]

I'm curious if any Grand Wagoneer owners are familiar if they kept the Air Pumps on the AMC 360 until their end of production (1991?). I've never seen a V8 with a pulse-air system but I've also never owned a full-size Jeep. It won't matter if you convert an Iron Duke Eagle or if you use a Howell TBI kit with your AMC V8. There's even a crazy expensive MPI kit available.

My 1985 Grand Wagoneer had an air pump mounted under the power steering pump with the 360V8. It also had a line that ran down to the cat

[captspillane]

Do you remember if there was a series of connected pipes going into the top of the exhaust manifold at each cylinder? There should not have been, since a motor will not have an air injection pump and an air pump. It sounds like they used an air pump piped directly through a check valve to the catalytic converter, similar to the electric pumps on Chevys. That's interesting. I didn't know that option existed. I figured they had a modified pulse-air system. It might help with a station wagon V8 conversion, since Iron Duke station wagons are crazy rare. I would never retain the manifold injection tube while rebuilding the exhaust, but I would consider keeping a catalytic converter injection pump. Did your 360 have double V belts? My '77 401 has redundant V belts everywhere, which I think is neat.

[Zoro]

Do you remember if there was a series of connected pipes going into the top of the exhaust manifold at each cylinder? There should not have been, since a motor will not have an air injection pump and an air pump. It sounds like they used an air pump piped directly through a check valve to the catalytic converter, similar to the electric pumps on Chevys. That's interesting. I didn't know that option existed. I figured they had a modified pulse-air system. It might help with a station wagon V8 conversion, since Iron Duke station wagons are crazy rare. I would never retain the manifold injection tube while rebuilding the exhaust, but I would consider keeping a catalytic converter injection pump. Did your 360 have double V belts? My '77 401 has redundant V belts everywhere, which I think is neat.

Yup, double groove. Sold that Jeep years ago, here's an old picture. I'll see if I have any better ones around

[ammachine390]

The air pumps were last used on the 258 in 1982. In 1983, they went to the pulse air system. The V8s never had a pulse air system, as pulse air was partly controlled by the ECM, and the V8s models didn't come with ECMS. They did however use an air pump.

[Zoro]

The air pumps were last used on the 258 in 1982. In 1983, they went to the pulse air system. The V8s never had a pulse air system, as pulse air was partly controlled by the ECM, and the V8s models didn't come with ECMS. They did however use an air pump.

Thanks for clearing that up! Forgot that only the 6 cylinder(Jeep) models got the funky ECM.

As for the Eagle in question in my original post. I'm going to fix what I can for right now, the eventual plan for this car is a 4.0 head swap +EFI.

[carnuck]

The V8s in CA got AIR pipe on the cat and AIR manifolds. They didn't pass CA's '93 emission reg because they weren't going to waste money on a non-Mopar engine.

[IowaEagle]

My my '82 SX/4 258 had an air pump when I got it.  It is now being bench tested, I just can't find the bench.  My '80 Concord still has a functioning air pump on it's 258.

[milliard431]

For clarity sake, we need to agree on some terminology.  I use the terms "Air-pump" or "Pulse-air."  Specifically I mean “Air Injection Pump” when I write “Air Pump.” For those who are not familiar, many AMC motors had an air pump powered by a V belt that put positive pressure directly to a vacuum controlled valve. When that valve opened, it injected air directly into the exhaust manifold. Air Injection pumps were found to cause detonation problems and could cause damage to the engine. It was replaced in both Jeeps and AMC cars by the “Pulse-air” system around 1983. That was a series of check valves and vacuum actuated solenoids that injected air directly into the side of the catalytic converter. The term “Air-pump” can also refer to a glorified electric fan hooked up to the injection line on the side of the catalytic converter. That’s common to other types of cars and trucks, but was never installed in any AMC or Jeep vehicles.

Some early Eagles still had bolts plugging the hole where the injection line was designed to attach. By 1983 the casting had changed and a flat spot replaced the holes in the exhaust manifold. None of my ’80 to ’83 Eagles had an Air Pump when I got them, so I believe that Eagles never had them. All the Spirits I’ve encountered did and several of my CJ7’s did. The AMC Eagle was classified as a light truck, so it had some subtle differences in emissions requirements from the Spirit. It was the light truck classification that let the Iron Duke Eagle motors go without any air pump system while the passenger car classified Spirits needed an air pump with the Iron Duke (thats also why Spirits have those hideous front bumper mounts and Eagles do not).

For PA state inspection on my Spirit I used an electric Air Pump from a Chevy S10, circa 1995. That went through a check valve to the side of the catalytic converter. Since the systems all accomplish the same goal of making the catalytic converter more efficient, they are all interchangeable legally. These systems also can be eliminated legally when you convert to fuel injection, since you are updating your emissions system to newer standards and equipment.

You obviously know way more than the average shade tree mechanic and this is exactly why I hate it when some one with less knowledge just rips out all the emissions equipment on these old cars. They  were designed to work WITH it and few people would know that a part from a S-10 would work as a bypass. It's just easier to figure out what went wrong when all the parts are still there.

[Zoro]

It is now being bench tested, I just can't find the bench. 

LOL

[BenM]

Air injection was introduced prior to catalytic converters and many cars continued to use it in conjunction. The 82 Eagle parts car and the 76 Pacer both had smog pumps, exhaust injection tubes, a relief valve, and an diverter valve. The valves controlled weather the air was injected above the exhaust valves, into the cat, or released. This was done in 82 by the computer, but in earlier cars through a complex series of vacuum amplifiers, valves, and delays.

The biggest hurdle is making sure the exhaust manifold doesn't glow red with too rich a mixture and a constant supply of air, then making sure the cat doesn't do the same. Then it's trying to heat up the cat as fast as possible to get it working, which is the exact opposite problem.

Switching over to pulse-air not only removed the smog pump, but also limited the amount of air that could be introduced and moved the upstream (or cold) injection point out of the exhaust manifold. That prevented the glowing red manifold and made the oxygen sensor a more reliable tool.

The AMC V8 was virtually unchanged after 88, and since AMC had just developed the new 2.5 and 4.0, they hadn't gotten to the V8 yet, so it only got carryover parts. The emissions system is awfully similar to the 1980 258.