AMC Eagle

[beat_truck]

Originally Posted by MadMan

https://www.allpar.com/mopar/lean-burn.html

The short version is that the guys at Chrysler discovered that if they had super precise control over the ignition timing, they could run the carb super lean and still achieve the same performance as a richer mixture with a regular old fashioned vacuum advance distributor. Yes, it was motivated by meeting emissions standards, but in theory that sounds plenty better than the 'old way' and it should improve fuel economy and keep the same performance.

It was a simple system, but not as simple as you might think.

The system measured:
1. Engine speed (r.p.m.).
2. Engine load. [likely the MAP vacuum]
3. Throttle position.
4. Speed of throttle movement.
5. Air temperature entering the engine.
6. Engine coolant temperature.
7. Carburetor throttle open or closed.
8. Engine starting.

As for the old fashioned carburetor and ignition system being 'better' - that sounds entirely typical of all the grumbly old farts in the repair industry. It's not that anything is 'better' it's that they are used to something being a particular way. They all said the same things about fuel injection, front wheel drive, unibody, disc brakes, MacPherson struts, I could go on and on. I'm sure that 'many people' also thought that hand cranking your engine was 'better' than having a starter, and that acetylene lamps were better than those new-fangled electric lights. lol You could probably go even further back and some guy would've said that steam was better than internal combustion.

The v8s might have had all of those sensors, but most slant sixes did not. It seems that only the very last couple years did. My '83 didn't have most of them. As I said, it had the Lean Burn box on the air cleaner, but it had a normal 1bbl carb with no sensors attached. And no, the truck hadn't been altered. It matched up exactly with the emissions tag on the inner fender and the rebuild kit that I bought for the carb, and no wires were cut up.

Like I said, that system might have looked good on paper, but like most of those abortions that were created as a stop gap between regular carbs and fuel injection, they didn't work well in reality. Especially as they aged.

I was eventually going to ditch the Lean Burn setup for a regular vacuum advance distributor, but I sold the truck after hitting a deer with it.