BRS wrote:
Ha, I thought (after hitting post) someone would ask that. With the over-rich idle mixture, as I have, obviously it's too low else it would not die. I think its in the range of 700 RPM, however when I agressively ground lean, it goes up to something line 1300 RPM. Today I'll warm it up and get the exact numbers.
However, I feel that bumping up the RPM to fix an overly rich mixture is a 'FIX' that should be considered after doing what is possible to have good fuel metering. It might come to that. But then the side-effect is possible fouled plugs unless I lean at idle. This bring me back to...
NWade wrote:Are you sure the issue is “too rich” at idle?
Have you looked at your fuel flow when you pull back to idle and noticed whether it ever goes to zero or near-zero?
And do you have a gascolator or un-insulated fuel lines in the engine bay?
—Noel
karmarepair wrote:It's worth remembering this fuel system does NOT like rapid throttle opening.
Onex107 wrote:...
The higher the number the more the taper angel increases.... What I found was that the sweet spot on the needle for wot was at a thickness of approx. .080, no mater what the needle number was. And the sweet spot on the needle for idle is very near the beginning of the taper. So the problem is getting the idle sweet spot in the right position after wot is set. I think your problem is the same as mine was with the lower number needles, the lower angle sets the two sweet spots further apart. I ended up with a #3 needle which when set for wot allowed the engine to idle without a mixture change. I took off with the mixture set about halfway out. I leaned a little more at cruise for economy. Exhaust gas temp. 11-1200. I landed, taxied, and never touched the mixture again until the next flight.
Bryan Cotton wrote:I found this cool picture on another thread:
..pic removed..
I assume you remember it! It would seem the #3 needle gives a quicker change from rich to lean. Isn't this what you were looking for?...
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