AMC Eagle

[beat_truck]

Originally Posted by old_tv_nut

The regular vacuum advance was not precise enough to produce the right setting under all conditions. Plus, spark was deliberately retarded from optimum performance on the early pollution-conscious cars. And with no feedback, the result would deteriorate between tune-ups.

How was that primitive Lean Burn setup any more precise? It didn't monitor any other engine parameters like temperature, exhaust gasses, air flow, or anything else. I'm pretty sure it literally just monitored the vacuum from the same carb port that would have went to the distributor, and nothing else. The Lean Burn "computer" even had a diaphragm that looked very similar to what is mounted on a regular vacuum advance distributor. At least that's how my '83 was.

On paper it might have looked better, but nearly all people that replace it with late '70s electronic (no points) vacuum advance distributors report better performance and usually economy too.

[old_tv_nut]

Originally Posted by beat_truck

How was that primitive Lean Burn setup any more precise? It didn't monitor any other engine parameters like temperature, exhaust gasses, air flow, or anything else. I'm pretty sure it literally just monitored the vacuum from the same carb port that would have went to the distributor, and nothing else. The Lean Burn "computer" even had a diaphragm that looked very similar to what is mounted on a regular vacuum advance distributor. At least that's how my '83 was.

On paper it might have looked better, but nearly all people that replace it with late '70s electronic (no points) vacuum advance distributors report better performance and usually economy too.

I didn't mean to imply anything about the primitive Lean Burn System, which I know nothing about, just pointing out what it was supposed to improve.
All the early smog fixes made performance worse, as far as I know, and I can easily believe that this one made no reliable improvement in smog either.