rjcthree
Well Known Member
When setting idle mixture, the requirement is something like "set idle mixture such that when moving mixture to ICO, there is to be about a 50 RPM increase before RPM falls off".
How fast does one move the mixture knob for this test? Like you're trying to shut the engine down by going to ICO (fast) or incrementally, or like you're trying to find the RPM number (slow)? I've not been able to find a definitive answer. Today, if I move it fast, I hit the the 50 RPM number, but I have to look at the EMS data to see it. If I roll out mixture turn by turn slowly, I can get 250 RPM rise consistently and with steady running, hot or cold.
My perception (low EGT, smell, slight miss at 1000 RPM in flight that is smoothed by leaning) is that I'm rich at idle. I just don't want to chase this any more than I have to.
Thoughts?
How fast does one move the mixture knob for this test? Like you're trying to shut the engine down by going to ICO (fast) or incrementally, or like you're trying to find the RPM number (slow)? I've not been able to find a definitive answer. Today, if I move it fast, I hit the the 50 RPM number, but I have to look at the EMS data to see it. If I roll out mixture turn by turn slowly, I can get 250 RPM rise consistently and with steady running, hot or cold.
My perception (low EGT, smell, slight miss at 1000 RPM in flight that is smoothed by leaning) is that I'm rich at idle. I just don't want to chase this any more than I have to.
Thoughts?
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