[MIPS]

Originally Posted by MadMan

If you take some time to learn the systems and controls, it will all make sense. And contrary to popular opinion, all that 'emissions junk' on the engine barely hurts performance. Excepting, perhaps, EGR, but that's something most cars still have today. (The real affect of all that 'emissions junk' was way too many vacuum lines and components on the engine, making diagnostics a pain in the ass). What really bogs down these old cars is how the carbs are adjusted to minimize NOx and unburnt fuel in the exhaust. Makes them run pretty lean, and saps their power. Whereas a fuel injected motor can make adjustments in realtime, and easily compensates for it.


I'm curious now what the extent of the carb controls are on this car. It does have an O2 sensor...

My problem is that I've never really worked with a large carbureted engine before so everything being learned here is completely new. I am trying to separate the original facts from "I learned how to tweak the engine like this" stuff that developed over decades of being passed on so I can't tell what was really a performance killer because it genuinely was or it's said to be a performance killer because "those guys in suits tried to put a computer in my beloved AMC and say it will make things better" and other muscle car junk I'm really not interested in.
Also coming from people who work with old computers, christ some of these people suck at keeping splices clean and cabling organized.

As for the vacuum diagram, this one is pretty close to my engine. Just omit the P/Air solenoids.


On the electronics side, here's some details I pulled when I was researching the purpose of the diagnostic plugs when there should be no actual computer interface in a car this old. It's all just status outputs for the various solenoids, relays and sensors. Coming from my TBI Geo Tracker this type of simple ECU style is really easy to diagnose component faults because the sensors are not running a modern communications protocol and when all else fails, the ECU gives off blink codes and doesn't actually need specialty tools to test.

Originally Posted by Eric H

The vacuum solenoid may be for the Idle up actuator which is the solenoid and vacuum item attached to the carburetor.
The electrical part is to set the idle, when you shut the car off it retracts, closes the throttle completely and prevents it from dieseling.
The vacuum part kicks in through the vacuum solenoid and idles it up whenever the compressor kicks in, ideally it's adjusted so the idle speed stays the same with the a/c on.

Yeah I linked to an article about its purpose in a later Jeep using the same carb. It's really not so much an emissions control component.
I did a very, very quick search on a hunch and the part sells under Carter and Mopar part numbers as well and is relatively cheap.