Lycoming IO-360 Fuel Nozzle torque and "A" position

[Guest]

6 hours ago, redbaron1982 said:

So today I put everything back together with my AP and did a run-up and everything seemed fine.

One thing is that we had to adjust the throttle idle position. It was going all the way to 500RPM and running rough. We adjusted with throttle all the way back was idling at 750RPM. Anyway I usually idle at 1000RPM.

A test that I did, when doing the run-up at 2000RPM, I start pulling the mixture back, after RPMs peaking, I continue to lean and the RPM started dropping, I continue leaning until RPM dropped all the way 1500RPM but running smooth. I assume this is a good thing, I understand this gives an indication of even fuel distribution across al cylinders.

We will see in the next flight how it behaves. I plan on running the Savvy profile, that should give me some valuable information.

Higher than usual idle RPM results in longer landing distances.

[Bartman]

When we installed my injectors after my 2020 rebuild they only went in a couple of threads before beginning to get tight.  Using the NPT tap I cleaned the threads, but being concerned about debris getting into the cylinder I used a shop vac while turning, and then stuck the shop vac over the entire tap periodically.  After screwing the tap in by hand I think I only turned it maybe one full turn, but in like 1/8 increments and applied the shop vac periodically.  After cleaning the threads, it made a big difference.

You definitely don't want the idle higher than specs or you will float, and someday at a short field, it may result in a rapid increase in sphincter tone.

[EricJ]

On 4/21/2023 at 8:33 PM, redbaron1982 said:

So today I put everything back together with my AP and did a run-up and everything seemed fine.

One thing is that we had to adjust the throttle idle position. It was going all the way to 500RPM and running rough. We adjusted with throttle all the way back was idling at 750RPM. Anyway I usually idle at 1000RPM.

A test that I did, when doing the run-up at 2000RPM, I start pulling the mixture back, after RPMs peaking, I continue to lean and the RPM started dropping, I continue leaning until RPM dropped all the way 1500RPM but running smooth. I assume this is a good thing, I understand this gives an indication of even fuel distribution across al cylinders.

We will see in the next flight how it behaves. I plan on running the Savvy profile, that should give me some valuable information.

+1 with the others mentioning the idle specs.    You really want it to be able to idle reliably at as low an rpm as possible in order to reduce float and landing lengths.   It really does make a big difference.   And idle mixture needs to be adjusted whenever idle is adjusted.   You have to kind of iterate between them a little bit to get it right.   Then once it's set nicely just use the throttle to keep ground idle just above 1000 rpm.

I typically check full-rich idle rpm at the idle stop during runup just to make sure that it will still idle at low rpm without quitting.   Otherwise the throttle is never actually set to run there on the ground.

[Fly Boomer]

4 hours ago, EricJ said:

You really want it to be able to idle reliably at as low an rpm as possible in order to reduce float and landing lengths. 

I flew a rental M20E a few hours, and the only way you could get it down was to grip the throttle and lean back.  Gets old pretty fast.

[redbaron1982]

Today we set it back to idle when cold at around 450rpm. Next flight after I come back I'll do an idle mixture test at 600RPM to see if mixture is ok.

I understand that this has to be done with the engine hot, that's why I want to make it after a flight.

[Shadrach]

7 hours ago, redbaron1982 said:

Today we set it back to idle when cold at around 450rpm. Next flight after I come back I'll do an idle mixture test at 600RPM to see if mixture is ok.

I understand that this has to be done with the engine hot, that's why I want to make it after a flight.

I have a mechanical tach and I’m dubious of its precision at idle speeds. What I can say is the engine is just ticking over with the throttle closed. It is not very smooth at idle and I don’t set it there during taxi. However when the plane is moving on approach or roll out with the throttle closed it’s perfectly smooth until it slows to taxi speed.

[redbaron1982]

On 4/21/2023 at 2:39 PM, Shadrach said:

I’ll be curious to know what your GAMI spread is. I’m betting it’s well under 0.5 

Yesterday I did a Savvy test profile and the GAMI spread in the three sweeps from rich to lean were: 0.2, 0.1, 0.3. So I´d average my GAMI spread in 0.2GPH. This was at 21.25 MAP and 2350RPM. The engine never run rough, I lean to a FF of 6.9GPH and stop there because the RPM were starting to drop.

This was my first solo and didn´t want to push too much, but I bet if I continue pulling the mixture out the engine would just quite rather than run rough.

[Shadrach]

27 minutes ago, redbaron1982 said:

Yesterday I did a Savvy test profile and the GAMI spread in the three sweeps from rich to lean were: 0.2, 0.1, 0.3. So I´d average my GAMI spread in 0.2GPH. This was at 21.25 MAP and 2350RPM. The engine never run rough, I lean to a FF of 6.9GPH and stop there because the RPM were starting to drop.

This was my first solo and didn´t want to push too much, but I bet if I continue pulling the mixture out the engine would just quite rather than run rough.

Good news! John Paul will likely tell you that your engine is not a candidate for GAMIs. Your spread is even closer than mine. I never run LOP at such low MAP settings.  I can lean past 100° LOP above 25inHg. I get a second EGT rise as it gets rough but I have no need to run that lean. Your in a very good place in terms of fuel delivery. Your engine will be smooth and efficient at any mixture setting.