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Thread: Roughness On Run Up

  1. #11

    Join Date
    Jul 2011
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    2,226
    Yes I could had used a standard massive electrode type of spark plug, that is one that looks like in a car engine. The repair shop had a massive one in stock. and it is about $50 as opposed to $140 for the fine wire one. But I prefer the fine wire type and that is what is recommended for my plane and engine. My plane is turbocharged, I live at 8000 ft and I often fly above 16,000 ft. The fine wires work better at high altitude and they last a lot longer. Even my old ones look old on the outside but the electrodes look almost new after hundreds of hours. So you get you moneys worth from them. If I had bought the massive one, then the next day Id have gotten the fine wire one so really paid twice.
    I don't know if the fine wires are do expensive because of precision needed or the iridium metal.
    There's no evidence of anyone dropping my plug, it has been a year and 100 hours since the annual and was running fine. I didn't drop them or ovetorque them. As for as dropping, plugs are shipped in boxes and fed ex or ups or whoever drops the boxes. I have some doubts it the plugs are really that fragile. I have put a dropped one on the tester and it fired normal. I may send the plug to Champion to see what they say.
    Last edited by Bill Greenwood; 09-26-2018 at 08:39 PM.

  2. #12

    Join Date
    Nov 2012
    Posts
    1,584
    Quote Originally Posted by Bill Greenwood View Post
    Yes I could had used a standard massive electrode type of spark plug, that is one that looks like in a car engine. The repair shop had a massive one in stock. and it is about $50 as opposed to $140 for the fine wire one. But I prefer the fine wire type and that is what is recommended for my plane and engine. My plane is turbocharged, I live at 8000 ft and I often fly above 16,000 ft. The fine wires work better at high altitude and they last a lot longer. Even my old ones look old on the outside but the electrodes look almost new after hundreds of hours. So you get you moneys worth from them. If I had bought the massive one, then the next day Id have gotten the fine wire one so really paid twice.
    I don't know if the fine wires are do expensive because of precision needed or the iridium metal.
    There's no evidence of anyone dropping my plug, it has been a year and 100 hours since the annual and was running fine. I didn't drop them or ovetorque them. As for as dropping, plugs are shipped in boxes and fed ex or ups or whoever drops the boxes. I have some doubts it the plugs are really that fragile. I have put a dropped one on the tester and it fired normal. I may send the plug to Champion to see what they say.
    Have you ever wondered why plugs come shipped like the do? In the protective container they come in? Even a quality auto plug will be protected in the box from such handling practices. Porcelain breaks very easy. The problem, when you crack the porcelain most time the porcelain will not come apart. It will hold together. Seeing how this porcelain is down deep in the plug you can not see this broken porcelain. Then under combustion pressure the plugs porcelain comes apart. The combustion camber is a very violent environment.

  3. #13

    Join Date
    Jul 2011
    Location
    Clarklake, MI
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    2,258
    Quote Originally Posted by 1600vw View Post
    I would want to know what caused the porcelain to break? In all my years I have never had this happen unless there was another underlying cause. Be it the plug was dropped, preignition..ect.
    Most common cause of porcelain fracture in service is detonation.

  4. #14
    FlyingRon's Avatar
    Join Date
    Aug 2011
    Location
    NC26 (Catawba, NC)
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    1,982
    Quote Originally Posted by 1600vw View Post
    Have you ever wondered why plugs come shipped like the do? In the protective container they come in? Even a quality auto plug will be protected in the box from such handling practices. Porcelain breaks very easy. The problem, when you crack the porcelain most time the porcelain will not come apart. It will hold together. Seeing how this porcelain is down deep in the plug you can not see this broken porcelain. Then under combustion pressure the plugs porcelain comes apart. The combustion camber is a very violent environment.
    Yes, the drop was just a guess as to "how could this have happened."

    1600VW is right about this. It's very hard to test for failure of these high tension insulators. And just because it passes after it was dropped doesn't mean it doesn't still have a latent defect that fails a time later.

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