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Thread: Rough O-200

  1. #21

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    Quote Originally Posted by Eric Brown View Post
    Gentlemen, I think this will be my FINAL REPORT.
    Took cold compression checks. All 77/80. Confirmed correct crank to cam gear indexing thru the RH mag mount hole. Reinstalled RH Bendix mag. Swapped spark pugs top to bottom. No change. Don't believe it is a vibration. It's scatter miss. Da......... da ......da..da..da...................da .......da.da.......... Shakes the airplane. Put the cowling on it and took to full power. Turns a smooth 2425 RPM with a Sensenich 6948 prop. I'm going to use it this way and see if it may improve (spook theory) over time. Figure to have the airplane back together and flying within 30 days.
    Your two symptoms of, it runs worse in cold weather, and it makes no difference where the idle mixture is set. makes me believe the carb idle circuit is not providing enough fuel when you are below the RPM of the cruise circuit.

    So my question would be, Is this a newly rebuilt Kelly carb?

  2. #22

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    Tom , remember Eric said he had even tried a totally different carb and no improvement. And if carb is really lean at idle then it would likely be hard to start, need a lot of prime and die soon when on idle. And there isnt a fuel pump in the system so even less to go wrong.

    Eric , a very long shot, but I tallked to an a&p working on a C172, and he said to look in exhaust pipe that sometimes baffles can come loose and partially block it.About the only other thing you havent mentioned it the door for carb heat. Is it secure and off when you are running the engine? Even carb heat partially on would enrich the mixture, but hard to see how it would be the miss you describe.
    Last edited by Bill Greenwood; 06-03-2017 at 10:45 AM.

  3. #23

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    Quote Originally Posted by Bill Greenwood View Post
    Tom , remember Eric said he had even tried a totally different carb and no improvement. And if carb is really lean at idle then it would likely be hard to start, need a lot of prime and die soon when on idle. And there isnt a fuel pump in the system so even less to go wrong.

    Eric , a very long shot, but I tallked to an a&p working on a C172, and he said to look in exhaust pipe that sometimes baffles can come loose and partially block it.About the only other thing you havent mentioned it the door for carb heat. Is it secure and off when you are running the engine? Even carb heat partially on would enrich the mixture, but hard to see how it would be the miss you describe.
    This would not be the first time I've seen two messed up carbs. and most folks start on primer fuel. and run above the idle circuit RPM.

    It would seem anyone assembling a new engine would inspect the mufflers they install.

  4. #24

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    Tom, re carbs, read Eric's first post again. The carb was Overhauled, along with mags etc. Then he even tried a complete 2nd carb with No change, No improvement, He doesnt say but Id guess the 2nd card came from an engine where it ran properly.
    So we can believe in the improbable that both carbs were, as you say, "messed up" with the same defect or more likely that as much as this sounds like a carb problem it is really something else.
    He could take his components, carb, mag etc, and run them One at a time on another engine that has been running well and see if he can duplicate the problem, thus isolating the cause, but that is a lot of trouble.
    Last edited by Bill Greenwood; 06-16-2017 at 08:59 PM.

  5. #25

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    Quote Originally Posted by Bill Greenwood View Post
    Tom, re carbs, read Eric's first post again. The carb was Overhauled, along with mags etc. Then he even tried a complete 2nd carb with No change, No improvement, He doesnt say but Id guess the 2nd card came from an engine where it ran properly.
    So we can believe in the improbable that both carbs were, as you say, "messed up" with the same defect or more likely that as much as this sounds like a carb problem it is really something else.
    He could take his components, carb, mag etc, and run them One at a time on another engine that has been running well and see if he can duplicate the problem, thus isolating the cause, but that is a lot of trouble.
    When he says the carb was overhauled, that is why I suspect the carb, Overhauled by who? the rest of your guess is just that, it would be pretext by he had several other engines to test stuff on. most don't.

  6. #26

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    Tom, seems we have a communication problem, or just are thinking opposite.

    Erics first post points out that the carb is overhauled, just as engine and mag are OH. So the carb seems suspect for the low speed miss. However in post #9 Eric writes "tried another O 200 carb", no improvment . Did you see that post?. So if the O H carb was the problem it is not likely that it would continue the same way with the 2nd carb. And he tried a 2nd mag and 2nd set of plugs so the problem is likely to be elsewhere.

    I dont really understand the wording of your last sentence. My point is that another way to test a suspect carb or mag etc is to put it one at a time on a good running engine and see if the miss then transfers to theg good engine. If not then the item is not where the fault lies.

    And Eric any updates for us? I really would like to know what cures this in the end
    Last edited by Bill Greenwood; 06-17-2017 at 06:10 PM.

  7. #27

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    Quote Originally Posted by Bill Greenwood View Post
    Tom, seems we have a communication problem, or just are thinking opposite.
    that's the problem with trouble shooting on line, you never know all it requires to get it right. all you can achieve is a SWAG.
    You don't know who overhauled what, or what the OP used to determine what the problem was. So all you can do is guess, So don't get indignant when I disagree.
    Last edited by Tom Downey; 06-17-2017 at 08:00 PM.

  8. #28

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    Tom, The trouble must lie with the first carb, the overhauled one,just as you say, even when it is no longer on the airplane, . Why couldn't I see that all along,rather then trying to discuss the symptoms and what Eric had already checked and ruled out?

    So it must be the carb that was overhauled, and even when it is not on the engine, it must have left negative vibes, that only occur under 1200 rpm.

    We once actually had trouble with an ovehauled carb on a SNJ, got it back from the oh shop and while the plane would start and run it would die at idle, Turns out the oh shop does a lot of duster engines which spend a lot of time idling and the shop had set the float level like they do in dusters, thus too lean for the SNJ.
    Last edited by Bill Greenwood; 06-18-2017 at 05:56 AM.

  9. #29

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    Gentlemen;
    I have been to the Flybaby website and reviewed every condition I thought held some merit. I have recently installed the wings onto the airplane.
    I have run the engine once since then. The miss and vibration were NOT as predominate as it was with the fuselage alone. Larger mass absorption ?? I have run several airplanes without wings that had small Continentals and did not experience this type of miss. At this point, all I can figure is that, mechanically (other than a possible lifter problem), there is nothing seriously wrong with this engine. Hopefully will fly I the next 30 days and re-evaluate.

    PS: about the carbs. The original carb a 10-4115-2, I overhauled (A&P / IA). The second carb a 10-4894, overhauled in 1997 by Consolidated Fuel Systems and has 500 hrs SOH.
    Last edited by Eric Brown; 06-17-2017 at 08:58 PM.

  10. #30

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    Bill, I have been rebuilding and repairing 0-200 and 0-300 Continentals for nearly 60 years. In that time period I have learned that the 0-200 was built by Continental.

    Next, how can any A&P rebuild a MA3-SPA carb and call it overhauled?
    read FAR 43.2 and tell me how any A&P in the field can test it as required by the overhaul manual.

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