Question Idle rpm for Lycoming IO-360?

[Neal]

Just a note to readers that don't own an airplane in the Experimental category; adjusting idle RPM and idle mixture is not classified as preventative maintenance. The posters likely have a repairman certificate issued for their particular aircraft.

I think what is discussed is a fine idea as well as being a very simple procedure, but to comply with FAR part 43 you would need a repairman's or mechanic certificate. Don't forget the engine logbook entry.

Let's take a moment to look at the reg and figure this out as what I'm finding, out of curiosity as to what someone without a repairman certificate can do. A quick search revealed this:

Non-Builder Maintenance | EAA

FAR Part 43 specifically states that the rules of that part do not apply to experimental, amateur-built aircraft. Therefore, any work (not just maintenance) on an experimental aircraft can be performed virtually by anyone regardless of credentials. (This does not apply to the condition inspection). Let common sense be your guide as to what maintenance you conduct yourself.

It seems rules you are referring to may refer to certified aircraft, not experimental or home built, etc.

 

[Waldom]

Yup.

Clearly any reasonable person can complete this task. The legal niceties apply to aircraft in the standard airworthiness category, which require an A&P for the work or a repairman in the case of an airplane in the experimental category.

The only reason I mentioned this is that if you are not rated and make the adjustments, keep your hangar doors closed while you're doing it. If you want a logbook entry, do the job with the knowledge and "under the supervision of" a mechanic and they will make the entry.

 

[Neal]

After tinkering a few times I have my idle dialed in. I had it a little higher than I desired around 760, that was a nice idle though but probably not the lowest stable that I was targeting. As it was quite windy yesterday I decided to tinker with this some more and now I'm down to around 650-660. It's amazing the difference in 100 rpm but this is a stable RPM for my plane and where I'm going to leave it. I think 700-800 is probably a sweet spot for a good idle, what CubCrafters set on mine leaving the factory of 550 was not stable and too low.

As to my idle mixture, while it ran great it was not showing the RPM increase of 10-50 rpm when pulling the mixture to full lean during cutoff at 1000 rpm. I had no rise in RPM. I adjusted the mixture 5 clicks rich and now I'm seeing the rise which is great. So I have that properly dialed in. I always taxi with the mixture about 50% out or showing a RPM rise, which now I'll be able to actually find.

Good getting the new plane dialed in. Now to go fly and have fun after this and coil pack drama.

 

[Cubonaut875]

Checked my idle RPM over the weekend, it appears my factory set is at 650.