Leaning question...Carbed O-360

Brantel · #1 05-05-2010, 09:08 AM

I understand from reading all the papers from Lycoming that they recommend that you run 50? ROP with my setup....

My question is what do you consider peak? When the first cylinder peaks or the last one?

Also, which cylinder do you use for determining the 50?? The first to peak or the last?

On my engine, when the last one peaks, the first to peak is over on the LOP side. I assume this is because it is a Carb setup.

All I was ever taught was the old method of lean till rough and then richen it a turn to a turn and a half.....

My CHT's run within 20? of each other. My EGT's run close except #2 which is always 100-125? less than the other three. It tracks consistently there so I think it is a proble placement issue. Overall my EGT's run higher than what others say theirs do. I think I placed my probes higher than most apparently???? The engine runs great and makes great power so it must be placement.

Radomir · #2 05-05-2010, 09:33 AM

Answer to the question is first to peak...

But I'd look into alternatives before accepting those things blindly. I prefer LOP.... and had run it that way even when I was carbed..

What ignition do you have? If you don't have an EI.. go get one.. long term it'll be cheap.. a lot cheaper than a pair of mags..

mahlon_r · #3 05-05-2010, 09:34 AM

You lean and manage mixture to the leanest cylinder, which should be the first one to peak. That way any of the other cylinders are being operated richer or the same as the leanest one, which you are using as the cylinder you, are managing the engine off of.
Good Luck,
Mahlon
?The opinions and information provided in this and all of my posts are hopefully helpful to you. Please use the information provided responsibly and at your own risk."

n5lp · #4 05-05-2010, 09:43 AM

Quote:

Originally Posted by Brantel

I understand from reading all the papers from Lycoming that they recommend that you run 50° ROP with my setup....

This isn't my understanding. Here is a quote from the Lycoming "Key Reprints" web page.

For a given power setting, best economy mixture provides the most miles per gallon. Slowly lean the mixture until engine operation becomes rough or until engine power rapidly diminishes as noted by an undesirable decrease in airspeed. When either condition occurs, enrich the mixture sufficiently to obtain an evenly firing engine or to regain most of the lost airspeed or engine RPM. Some engine power and airspeed must be sacrificed to gain a best economy mixture setting.

This is what I have been doing for over 40 years and still do. All the fancy instrumentation doesn't mean much when you have a carb. Just lean to rough then richen to smooth. Really really simple. I have all the fancy instrumentation so can see, if I choose to, that some cylinders are rich of peak, some are lean of peak and some are at peak. The solution to that is to not look at the fancy instrumentation.

Lycoming Web Page I reference

If you want to do something else, fine. I don't follow all off Lycoming's recommendations either, like what altitude to start leaning at.

reak · #5 05-05-2010, 09:44 AM

If you haven't already seen this Lycoming Flyer article, they address carborated engine leaning on page 37 paragraph 5.

http://www.lycoming.textron.com/supp...Operations.pdf

Basically Lycoming is saying EGT isn't very useful on a carb'ed engines, the best you can do is lean until rough then rich until smooth. I've following Lycoming's advice on my Superior O360.

regards,
Brad

Brantel · #6 05-05-2010, 09:57 AM

All good sources of info...

I used this doc as my reference:

http://www.lycoming.textron.com/supp...es/SSP700A.pdf

Seems that even Lycoming has different opinions within their own organization and or over the years.....

During my testing of different methods, the lean till rough and richen till smooth method seems to fall right into the 100? to 50? ROP range so I guess in a round about way it is following their advice.

Quote:

Originally Posted by n5lp

This isn't my understanding. Here is a quote from the Lycoming "Key Reprints" web page.

For a given power setting, best economy mixture provides the most miles per gallon. Slowly lean the mixture until engine operation becomes rough or until engine power rapidly diminishes as noted by an undesirable decrease in airspeed. When either condition occurs, enrich the mixture sufficiently to obtain an evenly firing engine or to regain most of the lost airspeed or engine RPM. Some engine power and airspeed must be sacrificed to gain a best economy mixture setting.

This is what I have been doing for over 40 years and still do. All the fancy instrumentation doesn't mean much when you have a carb. Just lean to rough then richen to smooth. Really really simple. I have all the fancy instrumentation so can see, if I choose to, that some cylinders are rich of peak, some are lean of peak and some are at peak. The solution to that is to not look at the fancy instrumentation.

Lycoming Web Page I reference

If you want to do something else, fine. I don't follow all off Lycoming's recommendations either, like what altitude to start leaning at.

Quote:

Originally Posted by reak

If you haven't already seen this Lycoming Flyer article, they address carborated engine leaning on page 37 paragraph 5.

http://www.lycoming.textron.com/supp...Operations.pdf

Basically Lycoming is saying EGT isn't very useful on a carb'ed engines, the best you can do is lean until rough then rich until smooth. I've following Lycoming's advice on my Superior O360.

regards,
Brad

Brantel · #7 05-05-2010, 09:59 AM

Maybe next year I will...I am thinking P/Emags at this point. Seems they have most of their growing pains behind them....

Quote:

Originally Posted by Radomir

Answer to the question is first to peak...

But I'd look into alternatives before accepting those things blindly. I prefer LOP.... and had run it that way even when I was carbed..

What ignition do you have? If you don't have an EI.. go get one.. long term it'll be cheap.. a lot cheaper than a pair of mags..

n5lp · #8 05-05-2010, 10:05 AM

Quote:

Originally Posted by Brantel

All good sources of info...

I used this doc as my reference:

http://www.lycoming.textron.com/supp...es/SSP700A.pdf...

Brian, the document is a little vague but it seems to refer to injected engines and in particular the companies that promote balanced injectors.

There are many ?experts? today with new products and techniques to help customers in the operation of their engines. One that is receiving public attention by way of aggressive advertising is a company manufacturing fuel injection nozzles and espousing an operating technique that is ?better? than that recommended by the engine manufacturer.

I don't think it supersedes the recommendations for carbureted engines operated at 75% power or less.

Brantel · #9 05-05-2010, 10:15 AM

Yep, most likely. It is date 2000 as well...

Quote:

Originally Posted by n5lp

Brian, the document is a little vague but it seems to refer to injected engines and in particular the companies that promote balanced injectors.

There are many ?experts? today with new products and techniques to help customers in the operation of their engines. One that is receiving public attention by way of aggressive advertising is a company manufacturing fuel injection nozzles and espousing an operating technique that is ?better? than that recommended by the engine manufacturer.

I don't think it supersedes the recommendations for carbureted engines operated at 75% power or less.

Chino Tom · #10 05-05-2010, 04:36 PM

Lean till rough then richen to smooth is what I do also. But having the info
on all 4 cylinders is heplful. When I was running two mags, leaning till rough
was only one cylinder going past peak EGT. Continueing to lean until the
2nd cylinder peaked, had the first on the lean side and the engine really running rough.
After installing one LSE Plasma II electronic Ignition, the engine would actually run with
all the cylinders having peaked. But there is no way my carbed O-360 could ever run
lean of peak. I usually cruise at 65% or less and always pretty high (8K+, mostly 9.5 - 10.5)
and leaning rough to smooth works out that the first cylinder to peak is #1 then going
to the lean side where its starting to run rough (sometimes #2 peaks but not always)
then richen to smooth brings #1 back to peak or slightly rich (<25 deg rich). The other
cylinders never peaked. This is still leaner than when I had two mags. My CHTs are
within 15 deg of each other (usually around 375) and although I tried my best to position
the EGT probes the same distance from the exhaust port, the right side runs as much
at 75 deg hotter than the left (specifically #1 where the exhuast pipe bend is closer to the head)
at about 1300-1375.