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Mixture Adjustment

A

ALMARTON

Well Known Member
Hello folks,

I am new to RVs and to Lycommings previously having only flew ROTAX 912 that have no manual mixture adjustment.

Now that I own my brand new RV9A with a IO-320D1A I have been reading lots about mixture adjustment, EGT the lots.

Still by reading posts here some doubts came up.

I think during the engine break in time (it has only 9 hours from new yet) I should be using high power settings (65%-75%) with mixture adjustment on ROP 100F from peak to prevent cilinder glazing, right?

I was wondering when (engine time) would I be able to use LOP 50F from peak? Anf if after the break in time (maybe after 50 hours) using LOP 50F is a healthy practice for the engine ? Wouldn't use like 50F ROP (not so economical) but better for engine life?

Thanks for any answers or tutorial/tips on how to better operate my IO-320.

Regards
Alexandre.
 
Alexandre,

There are other factors to consider. What type of injection system do you have? Have the orifices been balanced for fuel flow? Do you have full engine monitoring with indicators for cylinder head temperature and exhaust gas temperature on each cylinder? Do you have an accurate digital fuel flow meter?

For break-in on a new engine, it is commonly advised to keep the engine power as high as possible and full rich during the first 12-15 hours of operation to seat the piston rings.
 
airguy said:
For break-in on a new engine, it is commonly advised to keep the engine power as high as possible and full rich during the first 12-15 hours of operation to seat the piston rings.
Click to expand...

A note here. If flying from high altitude airports, and higher altitudes because of terrain...........I can guarentee fowled spark plugs if running full rich. Very noticeable when performing a mag check. Since I start from a 4603' msl airport, I leaned the engine from the beginning. My engine broke in just fine.

L.Adamson --- RV6A
 
Well I do have a Dynom EMS to monitor all cylinder CHT and EGT and Fuel Flow.

Although I am not sure what brand my injection system is I know is a common and reputable brand pehaps BENDIX.

Is that of any help?

Thanks for any tips on how to better operate my IO-320 related to mixture.
 
L.Adamson said:
A note here. If flying from high altitude airports, and higher altitudes because of terrain...........I can guarentee fowled spark plugs if running full rich. Very noticeable when performing a mag check. Since I start from a 4603' msl airport, I leaned the engine from the beginning. My engine broke in just fine.

L.Adamson --- RV6A
Click to expand...

Correct - I should have said "run it slobbering rich" for breakin. I would rather deal with fouled (fowled? you ingesting chickens again?) plugs for 10-15 hours than overtemp a cylinder and glaze it. If he has EGT/fuel flow data, it's easy to stay on the rich side of peak regardless of altitude.
 
airguy said:
Correct - I should have said "run it slobbering rich" for breakin. I would rather deal with fouled (fowled? you ingesting chickens again?) plugs for 10-15 hours than overtemp a cylinder and glaze it. If he has EGT/fuel flow data, it's easy to stay on the rich side of peak regardless of altitude.
Click to expand...

If we're running slobbering rich..............we can't even taxi, without knowing something is amiss. It will also be lacking in takeoff power.
If it's a new Lycoming, that's been run in at the factory.........as mine was, Lycoming has their own instructions on leaning. Basically, when density altitude is 5000' feet. But that's not a hard rule either.

L.Adamson --- RV6A
 
Rules of thumb

ALMARTON said:
Hello folks,

I am new to RVs and to Lycommings previously having only flew ROTAX 912 that have no manual mixture adjustment.

Now that I own my brand new RV9A with a IO-320D1A I have been reading lots about mixture adjustment, EGT the lots.

Still by reading posts here some doubts came up.

I think during the engine break in time (it has only 9 hours from new yet) I should be using high power settings (65%-75%) with mixture adjustment on ROP 100F from peak to prevent cilinder glazing, right?

I was wondering when (engine time) would I be able to use LOP 50F from peak? Anf if after the break in time (maybe after 50 hours) using LOP 50F is a healthy practice for the engine ? Wouldn't use like 50F ROP (not so economical) but better for engine life?

Thanks for any answers or tutorial/tips on how to better operate my IO-320.

Regards
Alexandre.
Click to expand...

Rules of thumb for breaking inn and leaning:

1. stay below 5000 ft to reach minimum of 75% power.

2. Never N E V E R lean beyond peak EGT at or above 75% power
Beter stay 100 to 150 degrees Rich of Peak.

3. Do not bother on economy during break in period (50 hours).

4. At or below 65% power (24x24 square) Peak EGT.

5. The MOST important: watch your CHT EGT and oil temp to stay in the
green.

6. After Break Inn and under 75% power: Peak EGT for maximum economy.

( source: Textron- Lycoming.com ) ...http://www.lycoming.textron.com/support/troubleshooting/resources/SSP700A.pdf
 
Last edited:
Alexandre,

I?m in the process of breaking in my new ECi O-360 with a fixed pitch Catto prop right now.

I?m flying at 3000 ft MSL, full rich, and between 2500 and 2650 RPM. This is getting me to 24 to 25? MAP, which is good.

I?ll vary the throttle some so I?m not on the same RPM all the time, which is recommended.

So far, so good with all the CHT?s, EGT?s, and oil temps well in the green.
 
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