T-ster

I have an older 3W100 that I was having issues with last week. I rebuilt the carb and sanded the phenolic block on a piece of glass and now it runs much better. However, I had the idle adjusted to a decent speed when I was warming it up (ran for 1-2 minutes mostly at idle with a few 1/2 to full throttle blips, however the idle did lower slightly during the warm up) and when I was landing I had to go around several times so I could trim the throttle down as it had picked up several hundred rpm from the initial idle speed.

I flew this engine 4-5 years ago and don't remember this being an issue. Does this mean the low speed adjustment is off, or simply once it warms up fully it has a better idle?

Tired Old Man

My Feedback: (1)

Many others encounter the same issue.

Until the engine has warmed up to about 80-90c (176-194f) or so the idle will be unreliable. The idle will gradually increase until the engine reaches it's ideal operating temperature. Tuning an engine when it's colder than the same temp causes problems later as well.

cyclops2

Pat Roy has given the absolute correct answer to so many erratic idle problems.

The engine NEEDS to be as hot as it can NORMALLY get.
Some engines never heat up enough from a cold start up, idle.

Do not be impatient on setting up the idle. Fly a while. Land. Adjust it with the engine still running after landing.


Rich