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Thread: Rough running o-200

  1. #1
    1piece@atime's Avatar
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    Rough running o-200

    I have a taylorcraft f-19 with the Continental O-200. Iíve been having some midrange issues when the oat is below 10*f. Today it was -4*f and with carb heat off it would run up to 2000 rpm then start cutting out, Iíd then add carb heat and it would run very smooth up to wide open throttle. While cruising at 2400rpm it would run smooth without carb heat, then when decelerated Iíd have to give carb heat to keep engine from stumbling. While landing Iíd leave the carb heat on Incase I needed to make a go around and taking off Iíd run up to WOT with carb heat then turn the heat off to get another 150rpm for max static of 2600 which is norma. My plane has a fresh overhaul with 100 hrs , good compression, mag drop is about 25rpm on each side, carb heat drop at 1800 is about 150rpm, oil temp after 1 hr is getting up to about 110 and Iím getting a rise of about 30 rpm with idle cutoff. My concern is if this is normal to need carb heat at a low cruise setting or if anyone has experienced similar symptoms. Iím hoping itís normal so I donít need to get my carb overhauled. Thanks. Adam

  2. #2
    cubdriver2's Avatar
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    Sounds like your lean, try backing out the big knurled screw on the backside of the carb out a 1/4 turn.

    Glenn
    "Optimism is going after Moby Dick in a rowboat and taking the tartar sauce with you!"

  3. #3
    cubdriver2's Avatar
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    Adam, did you get the skis on?

    Glenn
    "Optimism is going after Moby Dick in a rowboat and taking the tartar sauce with you!"

  4. #4
    1piece@atime's Avatar
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    Thatís what I thought, last week I backed it out 1/2 turn and was able to achieve a little rise in the rpm when leaning at idle. I flew right after and didnít notice any difference, maybe Iíll back it out a little more and see what it does.


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    I don't think it has any effect once the throttle is open past about 1/4.
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  6. #6
    1piece@atime's Avatar
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    Got the skis on and was able to test out today, Made a bunch of landings on some local lakes and everything seems to be working nice. Looking forward to some deeper snow, it was a little rough on Champlain with the bare ice and snow drifts.


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  7. #7
    cubdriver2's Avatar
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    Meet us down a Silver lake tomorrow

    Glenn
    "Optimism is going after Moby Dick in a rowboat and taking the tartar sauce with you!"

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    BC12D-4-85's Avatar
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    aktango58's Avatar
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    Two thoughts:

    First, what type of fuel are you running? With Auto fuel you could be building ice that quickly, my old T-craft would ice on full power climbs with mo-gas.

    Second, your mid jet is not large enough. At full power it is sending extra fuel through the system to keep it working, but once you come off of full throttle you lose that extra jet, so could be leaning it out.

    Maybe do a test on the ground, run her at the lower rpm and when she stumbles look at the exhaust. Is she blowing black smoke? If so you are rich and getting ice.

    If you are using mo-gas, maybe put 100 in her and see if it continues.
    I don't know where you've been me lad, but I see you won first Prize!
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  11. #11
    1piece@atime's Avatar
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    Im running 100ll. Iíll check for smoke but Iím sure itís getting to lean in that range. Another thought was maybe the air is too cold to vaporize the fuel without carb heat. At 2400 rpm the throttle is about 1/2 to 3/4 open if that helps, wide open puts me little over redline at cruise


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  12. #12
    1piece@atime's Avatar
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    Another thing. If I push the throttle in quickly it doesnít stumble. The accelerator pump seems to be working fine


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  13. #13
    BC12D-4-85's Avatar
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    I'm not an A&P but have flown a similar carb down to -30F on small Continentals in Cubs and Taylorcrafts. They will run leaner in colder temps normally, but I've not experienced stumbling or the need for carb heat to function in cruise. The engine from the carb intake to the intake valve needs to be free of any air leaks or they can run lean due to extra intake system air. That includes gaskets, rubber induction tube seals, and any primer line fittings or blocking plugs on the induction spider.

    When was the carb last overhauled or at least examined? There's nothing wrong with having it looked at if you're not sure if it's ok.

    Gary

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    1piece@atime's Avatar
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    Iíve had the plane for a year now and Iíd have too look at the logs to see when it was overhauled last. Before i owned it, it had been sitting in a box for awhile. Iím probably gonna pull it apart and give it a good cleaning or get a overhauled carb and start fresh but didnít want to spend the $ if it wasnít necessary.


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    BC12D-4-85's Avatar
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    Airplanes and engines have their own language. It's up to us to learn what they're saying. Do what's best for you and your plane this new year.

    Gary
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  16. #16
    skywagon8a's Avatar
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    It sounds like it's getting too much air. Cold air is more dense which would require more fuel for the proper mixture. By using carb heat you are reducing the density of the air. Try restricting the air flow at the intake with some duct tape. That big knurled screw is only for the idle mixture.
    N1PA
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  17. #17

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    The service bulletin I linked in post #10 shows how to fabricate a plate that attaches to the air intake to restrict the air during cold weather. I dealt with the same issue and this plate helped.

  18. #18
    1piece@atime's Avatar
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    Iíll try the plate and check for leaks. Thanks


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  19. #19
    Steve Pierce's Avatar
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    Quote Originally Posted by mam90 View Post
    Common issue. Several articles in the Cub Clues newsletter about this year's ago. The plate was the solution.
    Steve Pierce

    Everybody is ignorant, only on different subjects.
    Will Rogers

  20. #20
    Steve Pierce's Avatar
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    Quote Originally Posted by 1piece@atime View Post
    I’ve had the plane for a year now and I’d have too look at the logs to see when it was overhauled last. Before i owned it, it had been sitting in a box for awhile. I’m probably gonna pull it apart and give it a good cleaning or get a overhauled carb and start fresh but didn’t want to spend the $ if it wasn’t necessary.


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    Carb is usually overhauled with the engine.
    Steve Pierce

    Everybody is ignorant, only on different subjects.
    Will Rogers

  21. #21
    cubdriver2's Avatar
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    I never had any luck with the plate. I tried it on 3 different Cubs

    Glenn
    "Optimism is going after Moby Dick in a rowboat and taking the tartar sauce with you!"

  22. #22
    1piece@atime's Avatar
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    Thanks everyone. Iím going to head up there this morning and try the plate out.


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  23. #23
    aktango58's Avatar
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    Hope it works!

    I found that duct tape works great for any plate needs, and is more easily adjusted.

    One plane I had required frequent tape changes due to the OAT constantly varying. One day it would be 35, the next 10, then -10. I could take a piece off, or add when needed.

    And Glenn, It appears you only need the plate at mid throttle... which is a range you only pass through on the way to WOT
    I don't know where you've been me lad, but I see you won first Prize!

  24. #24
    1piece@atime's Avatar
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    I made a plate similar to the one in the service bulletin and Iím getting ready to try out. Hopefully it makes a difference.
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  25. #25

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    If it doesn't make a difference, turn it 90 degrees and try it again. As mounted on your cowling I think it is going to function more like a venturi than a baffle. The drawing on the SB is typical of a J3 with a closer to vertical air intake so the plate functons as a baffle and slows the induction air.
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  26. #26
    1piece@atime's Avatar
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    I tried it today and it made the engine run smooth. The only problem I have now is that it is too restricting and caused a significant drop in static rpm. Iím contacting MARVEL-SCHEBLER tomorrow to ask some questions. Most 0-200a are running a 10-4894-1 and Iím running a 10-5128. The 10-5128 is for a 0-200A54. Going to see what the difference is and get one coming.


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  27. #27

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    Sorry for rescuing old post.
    Did you fix the drop in static rpm??
    Thanx

  28. #28
    1piece@atime's Avatar
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    It was a dirty carb, I tore it apart and cleaned it and then it ran fine. I ended up selling it because my wife got pregnant and we needed more room, now we own a Maule m-4-210

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    1piece@atime's Avatar
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  30. #30

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    Great!!, so you've improved
    I am pleased for you

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