Question Idle rpm for Lycoming IO-360?

[Tsquared]

I'm rarely in idle as well other than just a test, however, the other time I'm at idle is in some pattern work where I'm doing practice engine out or just trying to keep speed under control. So base and final may see idle throttle position, although windmilling will keep it around 1100-1300 I believe, and then on roll out and other rare scenarios. Good to know that your engine will remain running at any throttle position even if minimally used.

I read something about cold weather starts not to go to 1000 RPM right away. I welcome any feedback from your northerners about this. Should you keep the throttle full aft until you start to see oil temp rise for example? Or is it okay to go straight to 1000 RPM after start in any outside air temperature condition?

Don't forget that you will be in idle when your practicing power off stalls.... you guys do practice stalls right? My most recent flight had my RPM's at idle around 1300rpm while practicing my engine out landings. 1100-1300 rpm sounds right to me coming in to land at idle.

To the second point/question - Define "cold weather" please

I've heard the same story about keeping RPM's below 1000 on a cold start, just keep in mind that Lycoming recommends a preheat system anytime it's "cold". I've seen cold defined as temps below 10F. In some cases cold is defined as temps below 40F.

With the Tanis preheat (cylinder heads and engine oil) my cylinder heads are typically 80F warmer than ambient temp and oil is 35-40F warmer as well. For me I plug in my Tanis when temps start to hover around 40F or lower consistently. That said I still keep close eye on my oil temp after start and don't taxi or operate above 1000rpm until my oil temp is at least 120F in the winter. I know with some of the radial engined warbirds I've flown in, we don't taxi (ie rpm >1000) until the engine oil is up to temp regardless of the outside temp.

 

[Neal]

From the Lycoming manual:

 

[Waldom]

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.

 

[Neal]

Yes, I do have my repairman certificate and I recommend anyone that is eligible to have one, get it. Whether you use it or not, or feel capable or not, it's your privilege to have. Very simple to get with local FSDO.

 

[Neal]

Here is my video on this topic which also states this is for knowledge and if needed get your A&P to make adjustments.

 

[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.