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Basic Lycoming leaning?

s10sakota

s10sakota

Well Known Member
OK, I bought a Piper Cherokee to fly while I build my RV. Yes I know it will slow the build progress but I'm ok with that.

It's been 17 years since I've flown behind a Lycoming, but I have a 10 hour flight next week from TX to MI to bring it home. If I remember correctly we used to lean Lycomings by slowly pulling the mixture until it started to run rough, then push it back in about 100 RPM.

Of course there are more precise ways of leaning but there are just basic engine instruments in the ol Cherokee.

I just want to make sure I'm remembering correctly and that this will work as a very basic way of leaning the engine?

Thanks!
 
Piper Leaning

A Cherokee 180 was my first plane--flew that old beast for 5years. Sounds like mine had similar instrumentation--little to none!

I leaned to engine roughness, then enrichened until smooth--worked fine!

Hope this helps.

Cheers,

db
 
db1yg said:
A Cherokee 180 was my first plane--flew that old beast for 5years. Sounds like mine had similar instrumentation--little to none!

I leaned to engine roughness, then enrichened until smooth--worked fine!

Hope this helps.

Cheers,

db
Click to expand...

After everything I've read on this subject that's still about the best advice there is. Unless you have fuel injection and great instrumentation it will do you just fine.

If you want to get technical:

http://www.avweb.com/news/savvyaviator/savvy_aviator_59_egt_cht_and_leaning198162-1.html
 
you will be making some fuel stops. check your gal/hr at fill up to see what rate you are using. this will help verify leaning setting. ;)
IMG_1465.jpg
 
I lean by watching the tach rise while turning the mixture out and then twisting in one full turn when the ram's start to drop.
 
Mike Busch has some excellent leaning webinars on the SAAVY analysis site also on the EAA site.
 
woodmanrog said:
I lean by watching the tach rise while turning the mixture out and then twisting in one full turn when the ram's start to drop.
Click to expand...

That is pretty much the way I did it when I had no engine instrumentation beyond oil pressure, temperature and tach.
 
Ferry Flight

Just a suggestion: fly only about 1hr on the first leg to check fuel and oil consumption before flying longer legs. As for leaning with minimal instrumentation, lean to roughness then richen up to smooth operation while noting the mixture travel to get smooth then richen up again that same amount of travel. If you do this with a engine monitor it works out to about 75 ROP.


Don Broussard

RV 9 Rebuild in Progress
 
Per an A&P of the year who manages a couple hundred high priced piston engines:
Unfortunately, this POH guidance leaves a lot to be desired. 50°F ROP is almost precisely the worst possible mixture setting from the standpoint of engine longevity. The maximum cylinder head temperature (CHT) and peak internal cylinder pressure (ICP) occurs almost precisely at 50°F ROP. So using the "recommended lean mixture" assures that your engine operates at the hottest, most stressful corner of its operating envelope.

One more time..... http://www.avweb.com/news/savvyaviator/savvy_aviator_59_egt_cht_and_leaning198162-1.html

Within 25 degrees is cutting it pretty close. I tend to follow an expert's advice when available.....your results may vary.
 
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Call Lycoming and order the Operating Handbook for your engine and read it. There is a lot of good information in there and remember, the engine doesn't know or care what airplane it is in.
 
I have read Mike Busch's pieces and trust what he writes.

Question for all the folks who recommend leaning until rough and then richening until smooth - I assume this implies running LOP and that you are OK with that, since you will not notice roughness until well LOP. Is it possible that those using this technique are actually richening it back to precisely peak EGT without realizing it?

For those who are leaning without reference to engine instrumentation, I have just never heard anyone comment on where within the "red zone" of max CHT and combustions pressures (plus or minus peak EGT) they think they are when using the "lean until rough and back in" technique.
 
Here's a quote from the end of Mike Busch's article linked above.

I fly a Cessna 172 with no CHT or EGT or fuel flow instrumentation. How should I lean my engine?

After stabilizing in cruise and reducing power to the desired cruise RPM, slowly lean the mixture until you feel the onset of perceptible engine roughness. Then slowly richen just to the point that the roughness goes away. With your limited instrumentation, that's the best you can do ... and it's not a bad technique.
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Leaning

I also agree with Busch on leaning. Without a engine monitor you can only assume what the cht's/egt's are doing so be conservative, 70% power and below engine is not able to generate enough heat or pressure to hurt anything at any mixture setting, this is where lean till rough then rich till smooth works with no worries. Use the power charts with the adjustments for OAT to determine % power.

Don Broussard

RV 9. Rebuild in Progress
 
larrynew said:
Here's a quote from the end of Mike Busch's article linked above.
Click to expand...

I fly a Cessna 172 with no CHT or EGT or fuel flow instrumentation. How should I lean my engine?

After stabilizing in cruise and reducing power to the desired cruise RPM, slowly lean the mixture until you feel the onset of perceptible engine roughness. Then slowly richen just to the point that the roughness goes away. With your limited instrumentation, that's the best you can do ... and it's not a bad technique.
Click to expand...

But I'm still trying to resolve that technique with Mike's premise that it's important to stay outside the peak to 100 deg. ROP box. How do you know, or how do you ensure this technique does not place you right at peak EGT (or otherwise inside the "red box"), which is the worst place to run your engine, according to Mike?

Is it implied that if you enrichen just barely enough to stop the roughness that you then MUST be operating in the "safe" LOP zone?

I assume this primitive leaning technique assumes you are running below 75% power (where you can supposedly "safely" do whatever you want), but I did not see that specifically stated.
 
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After four years running my old Cherokee 180 (1966 model) the way I described in the second post, I installed a single probe egt Alcor instrument. Can't remember which cylinder it was on (this was back in the late 1980's) but it was the recommended cylinder from Piper. When using the technique I described and then looking at the egt, it put me right at peak for the cylinder measured. Can't tell you where the others were running, but the engine was smooth. And, btw, that old carbureted A1A in the Cherokee never gave me single problem---just changed the oil/filter and kept the plugs clean and gapped!!!!! Can't say the same for the angle valve engine in my Mooney 201.

Cheers,

db
 
Think positive, planes have been leaned the same way for decades without problems. Only since EMS's came out did we go crazy about how many degrees ROP to run. Before that we weren't blowing engines up.
 
Cherokee

1966 Cherokee 180 would have been an 0-360A4A. This was a unique engine that Lycoming built specifically for the Cherokee starting around 1965. It has a solid crank in the front main bearing area, cannot be converted to constant speed without replacing the crankshaft.
The Piper distributor that I worked for 1964-66, had problems with power loss on takeoff in a brand new Cherokee 180 with 0 360A3A. After much testing and modification by Lycoming the fix was the solid shaft engine. I never did believe Lycoming on this issue. The solid shaft engines became the desired engine for Pitts S1. In the factory Pitts S1 it was an IO 360B4A, a direct derivative of the A4A.
Back to the original topic, somewhere many years ago a Lycoming rep told me that Lycoming position on leaning for the normally aspirated engines is that below 75% power the engine cannot be damaged by mixture setting.
 
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