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Thread: magneto grounding

  1. #1

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    magneto grounding

    I have 0-360 with Bendix magnetos and a newer mag switch it L-R-start. When I leave mixture rich and shut it off with mags it sits there and fires on what seems to me on one cylinder?? Its defiantly not running on one mag its sputters but just seems like it hits on one cylinder?? I have checked grounds P leads everything seems to be in order. I am thinking the switch isn't grounded correctly?? It has to be a problem somewhere from SW to magneto?? any ideas would be appreciated thanks

  2. #2
    skywagon8a's Avatar
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    Residual heat is firing the remaining fuel in the cylinder. It is not a magneto ignition problem. When shutting off an O-360 it is better to run it at about 1000 rpm, pull the mixture to idle cut off, then as soon as it stops firing and before it slows down, close and hold the throttle until stopped. This will give you a clean no shake shut down. With the larger engines it is better to eliminate the fuel in the engine to make it stop rather than shutting off the spark.
    N1PA
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    PerryB's Avatar
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    Yep, clinkers in the spark plugs are causing a glow-plug effect. Its common. If you clean the plugs it'll probably go away for a while.
    After Monday and Tuesday, even the calendar says WTF !

  4. #4
    cubdriver2's Avatar
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    Quote Originally Posted by skywagon8a View Post
    Residual heat is firing the remaining fuel in the cylinder. It is not a magneto ignition problem. When shutting off an O-360 it is better to run it at about 1000 rpm, pull the mixture to idle cut off, then as soon as it stops firing and before it slows down, close and hold the throttle until stopped. This will give you a clean no shake shut down. With the larger engines it is better to eliminate the fuel in the engine to make it stop rather than shutting off the spark.
    That must be exciting on floats coming to a tight parking spot

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

  5. #5
    skywagon8a's Avatar
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    Quote Originally Posted by cubdriver2 View Post
    That must be exciting on floats coming to a tight parking spot

    Glenn
    Nope, just a matter of timing. If you have Pmags, just pull the mixture at idle and it stops smoothly.
    N1PA

  6. #6
    wireweinie's Avatar
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    Quote Originally Posted by Jack Smith View Post
    I have 0-360 with Bendix magnetos and a newer mag switch it L-R-start. When I leave mixture rich and shut it off with mags it sits there and fires on what seems to me on one cylinder?? Its defiantly not running on one mag its sputters but just seems like it hits on one cylinder?? I have checked grounds P leads everything seems to be in order. I am thinking the switch isn't grounded correctly?? It has to be a problem somewhere from SW to magneto?? any ideas would be appreciated thanks
    Is there a specific reason for shutting down with the mags instead of with the mixture cut off?

    Web
    Life's tough . . . wear a cup.

  7. #7
    cubdriver2's Avatar
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    Quote Originally Posted by skywagon8a View Post
    Nope, just a matter of timing. If you have Pmags, just pull the mixture at idle and it stops smoothly.

    In 4000hrs I've only shut down using mixture maybe 5 times. Always with mags

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

  8. #8
    cubdriver2's Avatar
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    Quote Originally Posted by skywagon8a View Post
    Nope, just a matter of timing. If you have Pmags, just pull the mixture at idle and it stops smoothly.
    Wow, I weave in and out of boat dock alleys and would kill a few boaters if I did that

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

  9. #9
    skywagon8a's Avatar
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    Quote Originally Posted by cubdriver2 View Post
    In 4000hrs I've only shut down using mixture maybe 5 times. Always with mags

    Glenn
    You can do that with the lawn mower engines which you use. The higher displacement/ compression ratio engines need some advance consideration.
    N1PA
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  10. #10
    cubdriver2's Avatar
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    Quote Originally Posted by skywagon8a View Post
    You can do that with the lawn mower engines which you use. The higher displacement/ compression ratio engines need some advance consideration.
    Never understood why aircraft engines shut down with mixture. I've been playing with all kinds of engines since I was 5. I drag raced a 68 Camaro with 12 to 1 compression and shut down with the key. Had friends with that compression and Vertex mag and they shut down with ignition. Every different aircraft (89) I've ever flown i shut shut down with mags. I think it's just a pilot ego thing to use mixture

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

  11. #11
    Eddie Foy's Avatar
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    Quote Originally Posted by cubdriver2 View Post
    I think it's just a pilot ego thing to use mixture

    Glenn
    You got me figured, Glenn. When I pull that mixture I get a woody.
    Eddie Foy
    "Put out my hand and touched the face of God"

  12. #12
    cubdriver2's Avatar
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    Quote Originally Posted by Eddie Foy View Post
    You got me figured, Glenn. When I pull that mixture I get a woody.
    TMI

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

  13. #13
    S2D's Avatar
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    Quote Originally Posted by cubdriver2 View Post
    In 4000hrs I've only shut down using mixture maybe 5 times. Always with mags

    Glenn
    Wow, 4000 hrs behind one of those little continentals without a mixture control !!! thats awesome !!!!
    Never mind, its not worth it !!!
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  14. #14
    cubdriver2's Avatar
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    Quote Originally Posted by S2D View Post
    Wow, 4000 hrs behind one of those little continentals without a mixture control !!! thats awesome !!!!
    I have a mixture control, it's to save gas, not to stop the noise

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

  15. #15
    cruiser's Avatar
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    Yea, we don't like him much either
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    Quote Originally Posted by cubdriver2 View Post
    That must be exciting on floats coming to a tight parking spot

    Glenn
    Lol. I had that happen. A nice fellow at a seaplane fly in was going to catch me at the dock until my engine kept dieseling. He ran for cover and left me to dock myself. I was committed with no way of stopping. It did finally shut of....(just in time)

  17. #17
    Olibuilt's Avatar
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    On floats when I go ducking in tight places, I approach with the mixture already pulled to almost engine shutdown, throttle at idle, on the left mag only, carb heat on.... If I get in trouble I pull or push the mixture. But I always shut down my O-360 with mixture control.

  18. #18
    Mauleguy's Avatar
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    I have never seen an 0-360 not diesel without pulling the mixture when the engine is warm/hot. I am a mixture user because I know it is going to stop the engine from turning. The only way I have found to stop the dieseling if just the key is used is to go WOT at the same time as tuning the key to the off position but not sure that is that great of a process for killing it.

  19. #19
    cubdriver2's Avatar
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    I hand prop on floats and even if I had a mixture control I would still use mag switch to kill it because it starts better that way. I'm running most times with one blade.

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

  20. #20
    PerryB's Avatar
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    Smile

    Quote Originally Posted by cubdriver2 View Post
    I'm running most times with one blade.

    Glenn
    We know...
    After Monday and Tuesday, even the calendar says WTF !
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  21. #21

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    I had the understanding that by killing an engine with the ICO rather than by the mags. , was so that no fuel is present if you were to have a bad mag. ground and the prop. got turned. Just a chance at adverting a bad mishap.

  22. #22
    cubdriver2's Avatar
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    True, but if your killing it with mags you would know that. No matter how you shut down prop should be treated as hot

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

  23. #23
    Mauleguy's Avatar
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    Cubdriver2, I got to ask what your secret is, and I am serious. I have done a lot of hand props and never had any engine fire on the first blade (2nd or 3rd a lot). I have also tried to use the key method without any success in hopes that it would make the next hand prop on a hot engine easier. What is the secret that makes your 89 different aircraft different from the hand full of aircraft I have tried to use your method with. These were mostly Lycoming 0-360 but I have also tried Lycoming 0-320 and 0-540.

  24. #24
    PerryB's Avatar
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    My 320 will almost always start on the first blade hot, if previously killed with the mags. I was doing this for a while a few years ago, when I went on a major weight/CG bender trying to eke out all possible performance. After rebuild (no I didn't crash it) it lost weight in all the right places and I'm back to the skytec starter. For those on floats who would like to use the mags, I think a more frequent plug cleaning schedule - especially the bottom plugs - would solve most of the dieseling issues.
    Last edited by PerryB; 02-19-2017 at 06:06 PM.
    After Monday and Tuesday, even the calendar says WTF !

  25. #25
    cubdriver2's Avatar
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    Quote Originally Posted by Mauleguy View Post
    Cubdriver2, I got to ask what your secret is, and I am serious. I have done a lot of hand props and never had any engine fire on the first blade (2nd or 3rd a lot). I have also tried to use the key method without any success in hopes that it would make the next hand prop on a hot engine easier. What is the secret that makes your 89 different aircraft different from the hand full of aircraft I have tried to use your method with. These were mostly Lycoming 0-360 but I have also tried Lycoming 0-320 and 0-540.
    Most of the stuff I've flown didn't have a mixture knob. I added it to my 11 and my 0200 18 to try to extend my fuel. I just got used to shutting down with mags. Even on the Stearman the owners standard shut down was with mags then WOT, and that would start with one or 2 blades also. The only real Lycoming time I have is behind that 225 in the Stearman and the 0320 pa12 I flew on floats. Most of the old stuff likes it juicy when cold and somewhat lean when hot?
    Also if your always hand propping you get smarter as to what each engine likes for a quick start, each one is a little different. Something I do that most don't is that I never pull any blades thru after priming. I go hot on the very first pull, that's the quickest way to " discover " what each engine likes. My only 0360 time I have was a couple hrs in a 04 Top Cub on floats and that seemed happy with the mag only shutdown

    Glenn
    Last edited by cubdriver2; 02-19-2017 at 02:51 PM.
    "Optimism is going after Moby Dick in a rowboat and taking the tartar sauce with you!"

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