Carbed LOP

OkieFlyer said:
Is the plug fouling issue because of the lead, or rather the lack of lead scavenging at the richer settings? If so, would running mogas eliminate the issue?
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Running unleaded fuel will always fix a lead fouling problem -- no lead, no problem.
 
Ron Levy said:
Which book? What aircraft? What is "early days"?
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just read the question, (post #12) quit trying to be cute. If you really don't know just say so.
 
Ron Levy said:
I give up -- you're the winner. Happy now? :rolleyes:
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Cessna changed from using the 0-300 and the 0-200 and started using the Lycoming engines, the 0-300/0-200 will run with two or more cylinders LOP and the rest of the cylinders in the Best power range, the lycomings won't.

the 0-300 the richest cylinder will be right at Peak when the leanest goes lean misfire condition. much better fuel distribution than the Lycomings.

That is why they had Cylinder problems later in the production run.
 
A person with a bit of interest, Devcon aluminum putty, and a monitor, could modify their plenum to achieve a more balanced flow. ;)
 
Tom-D said:
Cessna changed from using the 0-300 and the 0-200 and started using the Lycoming engines, the 0-300/0-200 will run with two or more cylinders LOP and the rest of the cylinders in the Best power range, the lycomings won't.
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Since the OP is flying a 182 with an O-470R engine, none of that is relevant.
 
Ron Levy said:
Since the OP is flying a 182 with an O-470R engine, none of that is relevant.
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What makes you believe the 0-470 is any different? the smaller engine run a little better fuel distribution but not much.

Cessna didn't really have many problems until they went to Lycomings. After that it became very apparent their instruction was wrong.

You have stated many times that the pull to vibration push to smooth will leave cylinders on the rich side of peak, TCM engine will tolerate that better than Lycoming.
Granted the smaller TCM engines do better than the big bore, but the 0-470 is no exception.
 
Tom-D said:
You have stated many times that the pull to vibration push to smooth will leave cylinders on the rich side of peak, TCM engine will tolerate that better than Lycoming.
Granted the smaller TCM engines do better than the big bore, but the 0-470 is no exception.
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Since that method is mentioned in the POH, and Cessna did not authorize running on the lean side, I assumed that all the cylinders would be on the rich side if you did it like that. If that method puts some cylinders on the lean side, then Cessna contradicted themselves.


P.S. I value all of you guy's input, so please don't get into a ****ing contest on this thread. It drives people away when we bicker, and it ultimately screws the guy that was seeking the info, which is me. Thanks. :)
 
OkieFlyer said:
Since that method is mentioned in the POH, and Cessna did not authorize running on the lean side, I assumed that all the cylinders would be on the rich side if you did it like that. If that method puts some cylinders on the lean side, then Cessna contradicted themselves.
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Do you have instrumentation to tell you when you are on either side of peak?

If you don't, how are you going to follow the owners manual?
 
If you want to run smooth LOP on a carb, the best thing to do is get a tuned exhaust.
 
Tom-D said:
Do you have instrumentation to tell you when you are on either side of peak?

If you don't, how are you going to follow the owners manual?
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Not really. Just single point EGT and CHT gauges.

When I started the thread I didn't realize just how important fuel injection and engine monitors were for leaning past peak EGT. Now I see that I really don't have much business messing with it without really having a clue where the other 5 cylinders are running, and with the poor induction system of the O-470. I did assume, however, that if the POH mentions the pull to roughness, push to smooth method, and it states that LOP is not authorized, then said method should leave all 6 cylinders ROP. I'm not saying it is so, but it was my assumption. The POH also recommends running 125°, 75°, or 25° ROP based on the single point EGT gauge. Where I've become confused, is where Mike Busch disagrees with the POH in running within 100° ROP because of ICP issues, while others, perhaps yourself disagree with Mike. All that being said, I still don't know where I can safely run my engine with engine longevity in mind, and still operate as economically as possible given my lacking instrumentation. I do appologize if I sound like a dunce, but this is really my first rodeo as an owner, and contradictory information abounds on this subject. I appreciate you guys sticking with me on this.
 
OkieFlyer said:
Not really. Just single point EGT and CHT gauges.
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Then there's no way for you to tell where you're running the engine other than that one cylinder, and it would be very, very unusual for that one cylinder to be definitive in how the other cylinders are operating. So, until you get EGT/CHT instrumentation on all six cylinders, just stick with "lean to rough then enrich to smooth" for cruise leaning, and you and your engine should be fine.
 
Ron Levy said:
Then there's no way for you to tell where you're running the engine other than that one cylinder, and it would be very, very unusual for that one cylinder to be definitive in how the other cylinders are operating. So, until you get EGT/CHT instrumentation on all six cylinders, just stick with "lean to rough then enrich to smooth" for cruise leaning, and you and your engine should be fine.
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Roger Wilco.
 
OkieFlyer said:
Roger Wilco.
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There other indicators of how you are running the engine.

Your spark plug are the best of the bunch. get your A&P to help you understand what they should look like.

Next you fly try this.

At cruise altitude level off pull the throttle/prop to your desired RPM & MAP then lean, watch the VSI. if it goes up, you are going toward the best power zone, trim level, then lean again, if the VSI goes up you are going toward the best power zone again, trim level, keep that routine up until you lean and the VSI goes down. enrichen until the VSI returns to level.

you are now making the best power that the engine can make at that throttle setting and altitude. Note that on your CHT, if the CHT is over the 400 richen the mixture, a little at a time until the CHT comes down.

This routine will place all your cylinders on the rich side of peak. Inspection after 5-10 hours on the plugs should tell you if you are too rich or too lean.
 
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Tom-D said:
There other indicators of how you are running the engine.

Your spark plug are the best of the bunch. get your A&P to help you understand what they should look like.

Next you fly try this.

At cruise altitude level off pull the throttle/prop to your desired RPM & MAP then lean, watch the VSI. if it goes up, you are going toward the best power zone, trim level, then lean again, if the VSI goes up you are going toward the best power zone again, trim level, keep that routine up until you lean and the VSI goes down. enrichen until the VSI returns to level.

you are now making the best power that the engine can make at that throttle setting and altitude. Note that on your CHT, if the CHT is over the 400 richen the mixture, a little at a time until the CHT comes down.

This routine will place all your cylinders on the rich side of peak. Inspection after 5-10 hours on the plugs should tell you if you are too rich or too lean.
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That makes good sense. Thanks Tom.
 
Ron Levy said:
Then there's no way for you to tell where you're running the engine other than that one cylinder, and it would be very, very unusual for that one cylinder to be definitive in how the other cylinders are operating. So, until you get EGT/CHT instrumentation on all six cylinders, just stick with "lean to rough then enrich to smooth" for cruise leaning, and you and your engine should be fine.
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I wonder how we did this prior to all the new gauges?
 
OkieFlyer said:
Well, someone did say that the O-470 ate a lot of cylinders. :dunno:
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and so we have the IO-520.

I have yet to see a 0-470 go to TBO with out cylinder replacement/overhaul/upgrade.

Do as I suggested, see how far down the airway you can get.
 
Tom-D said:
and so we have the IO-520.

I have yet to see a 0-470 go to TBO with out cylinder replacement/overhaul/upgrade.

Do as I suggested, see how far down the airway you can get.
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I'll do my best.


Thanks again, and thanks to all who have chimed in. Y'all are fine folks indeed.
 
OkieFlyer said:
Well, someone did say that the O-470 ate a lot of cylinders. :dunno:
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Not true unless you try to run one too lean. The problems with 470 cylinders are mostly historical. Valve guides would wear out. Repairable but most guys view cylinder repairs with disinterest when the engine is within a couple of hundred hours of TBO. All big bore TCMs see an occasional E valve seat problem. Another easy repair, and a good cylinder shop can tune the rocker arm/valve contact to prevent recurrence. On the other hand IO-520s had lots of years with lots of cylinder woes. Primarily cracking at the fuel injector boss. Lord know TCM has had their problems with cylinder compressions, too, and the 520 is probably the one that saw it most. But these days cylinders don't suffer those problems like they used to. With a 470, if you feed it enough fuel and run it hard? It'll reward you with good reliability.

I deleted an important piece of advice when things in this thread got silly. You really do need to establish your leaning authority to know whether your carburetor is lean, normal, or fat. Get the plane warm and go fly at a couple thousand feet. Establish your full rich cruise EGT. Now lean it slowly until it starts to stumble ever so slightly and enrich just enough to smooth it up. What's the EGT temp difference from full rich? Ideally you'll have about 150*. Some planes have more, so the carb is richer than average. Some planes have less. In that case the plane may be running too lean at take-off. My own plane, the last time I installed a factory 0-470, had 50* of leaning authority. TCM addressed it and got it up to about 100*. Still too lean in my book, but hard to prove with a single point EGT and without a fuel flow instrument. But those instruments aren't all-important as long as you can demonstrate the 150* temp spread. Assuming you can, lean per the POH and your engine should make you happy for a long time.
 
Tom-D said:
I wonder how we did this prior to all the new gauges?
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Just the way I said several times in this thread -- lean to rough, enrich to smooth. Worked then, works now. No need to make it any more complicated than that for engines like these.
 
It works with an assumption that the carb is within normal fuel supply limits. The past decade or so has seen carbs supplied as anything but normal or average. The OP needs to establish where his falls within that range. With that info he may have confidence to accept leaning advice. I'm surprised you 470 aficionados haven't talked about the carb variable.
 
Ron Levy said:
Just the way I said several times in this thread -- lean to rough, enrich to smooth. Worked then, works now. No need to make it any more complicated than that for engines like these.
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but you could end up being too lean. :yikes:
 
Ron Levy said:
Just the way I said several times in this thread -- lean to rough, enrich to smooth. Worked then, works now. No need to make it any more complicated than that for engines like these.
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When you advise that, are you willing to replace their cylinders ?
 
Stewartb said:
It works with an assumption that the carb is within normal fuel supply limits. The past decade or so has seen carbs supplied as anything but normal or average. The OP needs to establish where his falls within that range. With that info he may have confidence to accept leaning advice. I'm surprised you 470 aficionados haven't talked about the carb variable.
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The only method of figuring out if the carb is calibrated correctly with out a fancy gauge is experimentation and watch the color of the spark plugs, or the method I suggested above. After the power setting is made, in level flight you can virtually use the VSI asa horse power meter. better power makes the aircraft climb. best power range is as good as it gets, so if the CHT goes up, you have no other choice in the 0-470 except to enrichen the mixture.
you go farther lean, you will exceed the instructions given, as have already stated that is not advised by the manufacturer.
 
I know you say you fix them, but how many years of flying 470s do you have behind you? How many engine changes did you do and how did the values change with them? Your theory doesn't match my own experiences from flying them. And by the way, that includes before and after adding an EDM monitor and FS450 fuel monitor. Mr. Okie needs more info before he should adopt or dismiss any of this thread's advice.
 
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Tom-D said:
When you advise that, are you willing to replace their cylinders ?
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only if he's not lean enough.....and running smooth at peak EGT.:yikes:


but, how would anyone know that without an engine monitor?:dunno:
 
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