Amskeptic wrote:Old McDonald wrote:
1. Mixture screw turned 7 times before it seated...
then I put it back where it started (7 turns before)
2. After I nudged the needle a little bit, it kept running and seemed to be running ok... the RPM was in a good range, timing perfect.
3. Nudging the wiper a little clockwise/counterclockwise seemed like it didn't do anything to the revs, so I assume it may be okay. If YOU feel I am ready, I am ready for the next step!
So it is idling by itself when warm at a decent rpm?
1. Mixture Screw Forensics: based on your information above, none has tried to hide a vacuum leak by running to that screw. This is good. Please take two and a half turns clockwise as our initial value on the mixture screw. This places us exactly in the middle of its possible adjustment range.
2. With a fully warm engine that has even had a chance to drive down the road for a good 20 minutes, re-check the wiper by the aforementioned little nudges, but see if you can read a tach-dwell meter while nudging. Try to get the most optimal rpms you can +/- 25 rpm. Even an analog meter can be very accurate if you can discern a needle on one side of a hash mark moving to the other side. You do not need to actually have the needle directly over a hash mark on the scale, you can just move your eyeballs to either side of the meter until you see the needle appear lined up. After you lock your eyeballs at whatever angle was required to have the needle lined up with a hash mark (note that I don't really care what the actual rpm is, we are just trying to catch a subtle change), gently move the wiper in either direction to catch the Very Most Optimal RPM you can. If you then tell me that you gained 25 RPM when you pushed the wiper counterclockwise, we will note, you and I, that the idle is slightly leanish but do nothing about it yet. If you find that you gained 25 rpm when you nudged the wiper clockwise, we will know that it is slightly richish. Move the wiper some more in each direction if you got no noticeable change in rpms. You WILL drop the revs in BOTH directions if you get ham-handed about it, that's OK too, just tell me if the distance-to-rev-drop favored CW or CCW.
As a preamble to our AFM adjustments, just lightly read the below to prime your mind to start working on the concepts subconsciously.
The AFM provides a complete matrix in the three possible adjustments provided:
A) the wiper hold-down screw inside that little oval slot I call the
Static Adjustment
B) the black cog with the teeth around its perimeter I call the
Dynamic Adjustment
C) the mixture screw I call the "trim adjustment" this week.
Between the three adjustments, we have the ability to affect the entire matrix, i.e. the mixture map.
Rich.
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Lean
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Low RPM/Load . . . . . . . . . . . High RPM/Load
Since this current php site code is stuck on "left margin" I can't draw you a graph. Use your imagination. Imagine a direct 45* line from lean/low up to rich/high. That is a simple fuel consumption curve in a perfect theoretical world.
Your static adjustment (A) will move that line up or down maintaining the perfect 45* angle at all times. If you adjust the wiper CCW by loosening the hold-down screw and easing it over a tooth, you move that line up towards rich. Low speed/load, high speed/load, doesn't matter, the engine's entire experience gets richer.
Your dynamic adjustment (B) changes the slope of the map. Imagine a nice curve up towards "richer sooner", or imagine a curve towards horizontal which is "leaner later." If you rotate the black plastic cog (by prying the chrome lockwire away from a tooth with your regular screwdriver tip and rotate the cog CCW (richer) or CW (leaner) you either unwind the spring coiled in inside, or wind it up still further.
This adjustment primarily affects the higher rpm/load.
If you play with this adjustment, there will be some "blowback" on the idle adjustment which you then take care of the mixture screw.
Colin
(notice how I have not yet offer a procedure. . . . . .)