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Thread: Spark plugs

  1. #81

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    Quote Originally Posted by Steve Pierce View Post
    The ohm test does not work on the old carbon pile spark plugs. Joe Logie at Champion told me the ohm test is a marketing thing from Tempest. He said if the plug passes a pressure test it is good. I have always used my pressure tester and never had an issue. I believe with so many customers with engine monitors if there was an issue it would have happened already. I use Tempest plugs myself, can't see paying so much more money for a name. I have ohmed plugs with my Fluke meter and seems the results are all over the place. I will continue to use my spark plug pressure tester until it is proved to me a plug can pass that test and fail an ohm test and not work in the engine.

    Steve, I have had the experience of plugs (Champions) in a Husky that ran a bit rough...still ran, but just wasn't as smooth as desired. Resistances were upwards of 50Kohms on several of the plugs. They all passed testing with pressure tester. I replaced them with Tempests, and the roughness went away. (perhaps of interest, the EGTs had slight variance with the Champions).

    In discussion with George Braly of GAMI, they have found a lot of problems with high resistance in plugs that pressure tested okay, but would misfire at altitude. (see https://taturbo.com/frames.html).

    It makes sense in the context of Ohm's law....P=EI, I=E/R. As Resistance goes up, the amount of voltage required to generate enough power for the spark to jump the gap of the plug goes up as well. (exactly why the guy you helped had a problem....at low engine rpm, the mags weren't generating enough voltage for the spark to jump the (larger than normal) gap. A plug that has increased resistance demands more from the mag, which, in marginal conditions, can generate a misfire.


    I've seen it several times in Barons/Bonanzas at altitude...a plug will start misfiring, but down low will be okay, and will be okay on pressure testing. Often it has high resistance, and when replaced the problem goes away.


    (just my dumb country boy understanding, at any rate)

  2. #82
    JimParker256's Avatar
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    In my opinion, Champion stuck it to us as pilots for FAR too long, pretending there was nothing wrong with their plug design, refusing to acknowledge the issues with their plugs, and pooh-poohing the resistance tests that Tempest, Mike Busch, George Braly and many others in the industry were advocating.

    Then recently they very quietly released a brand new plug design with a much better resistor design that is far less prone to cracking and shorting. Now they are no longer quite so adamant in claiming that the resistance tests are bogus.

    You do the math...

    Me – I'll just stick with Tempest plugs, since they haven't had the same issues and generally cost less.
    Jim Parker
    2007 Rans S-6ES
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  3. #83
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    Quote Originally Posted by Firepilot View Post
    Steve, I have had the experience of plugs (Champions) in a Husky that ran a bit rough...still ran, but just wasn't as smooth as desired. Resistances were upwards of 50Kohms on several of the plugs. They all passed testing with pressure tester. I replaced them with Tempests, and the roughness went away. (perhaps of interest, the EGTs had slight variance with the Champions).

    In discussion with George Braly of GAMI, they have found a lot of problems with high resistance in plugs that pressure tested okay, but would misfire at altitude. (see https://taturbo.com/frames.html).

    It makes sense in the context of Ohm's law....P=EI, I=E/R. As Resistance goes up, the amount of voltage required to generate enough power for the spark to jump the gap of the plug goes up as well. (exactly why the guy you helped had a problem....at low engine rpm, the mags weren't generating enough voltage for the spark to jump the (larger than normal) gap. A plug that has increased resistance demands more from the mag, which, in marginal conditions, can generate a misfire.


    I've seen it several times in Barons/Bonanzas at altitude...a plug will start misfiring, but down low will be okay, and will be okay on pressure testing. Often it has high resistance, and when replaced the problem goes away.


    (just my dumb country boy understanding, at any rate)
    Had a similar problem with a j-3. Between the plugs and the owner trying to adjust the mixture on a stromburg and forgot to tell me.


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  4. #84

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    Plenty of failure points between the mag drive gear and the spark plug tip, the spark plug is the easiest to replace and likely gets the blame for other problems up the chain. I'll stick with my tried and true pressure test, it has worked fine for me for over 40 yrs. As far as brands go, I'll install whatever flavor the customer wants, they all work fine with hot mags timed properly.
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  5. #85
    Steve Pierce's Avatar
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    I guess it is hard for me to see a spark plug passing a pressure test on my spark plug tester and failing an ohm test. Maybe I will find one.
    Steve Pierce

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    Will Rogers
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  6. #86

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    The best aircraft spark plugs are automotive spark plugs.

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  7. #87
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    Quote Originally Posted by stewartb View Post
    The best aircraft spark plugs are automotive spark plugs.

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  8. #88
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    Quote Originally Posted by stewartb View Post
    The best aircraft spark plugs are automotive spark plugs.

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    They working good in you Cessna?
    Steve Pierce

    Everybody is ignorant, only on different subjects.
    Will Rogers

  9. #89

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    Nope, but that's a testament to archaic regulations, nothing else. Maybe someday the government will get out of the way of private owners. My Cessna motor could be SO much better.

    My Cessna uses Champion plugs and Slick mags. They've served me well. I couldn't care less what the internet thinks of either. But still, my initial statement is the truth.
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  10. #90
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    Been working on to many Carbon Cubs with Lightspeed ignition. If there is an issue with the coil pack, terminal comes lose etc, the plug is trashed. Easy to replace but threw another element into the troubleshooting procedure after you figure out you have multiple issues. I find very few spark plugs related issues with certified engines but it does save time to throw the old ones in the trash and install new instead of cleaning and testing the aircraft versions
    Steve Pierce

    Everybody is ignorant, only on different subjects.
    Will Rogers
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  11. #91

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    Quote Originally Posted by Wingwrench View Post
    Plenty of failure points between the mag drive gear and the spark plug tip, the spark plug is the easiest to replace and likely gets the blame for other problems up the chain. I'll stick with my tried and true pressure test, it has worked fine for me for over 40 yrs. As far as brands go, I'll install whatever flavor the customer wants, they all work fine with hot mags timed properly.
    So you are willing to providing your customers only half of the tests that are required for spark plugs? How much an hour do you charge that you cannot spend 3 minutes to check the resistance on 8 spark plugs in a cub? Its an easy check and I personally have found enough failures to continue. Oh and my work has 50 airplanes in their flight school, and 15 of them are Lycomings so I am seeing more use and abuse issue than I ever did with most private GA customers. Tim

  12. #92

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    Quote Originally Posted by Steve Pierce View Post
    I guess it is hard for me to see a spark plug passing a pressure test on my spark plug tester and failing an ohm test. Maybe I will find one.
    You will if you start doing the test Steve, unless all of your customers are like Windy who have to change some yearly because she is flying 4-500 hour per year.

  13. #93
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    Quote Originally Posted by astjp2 View Post
    So you are willing to providing your customers only half of the tests that are required for spark plugs? How much an hour do you charge that you cannot spend 3 minutes to check the resistance on 8 spark plugs in a cub? Its an easy check and I personally have found enough failures to continue. Oh and my work has 50 airplanes in their flight school, and 15 of them are Lycomings so I am seeing more use and abuse issue than I ever did with most private GA customers. Tim
    Guess I haven't seen the requirement nor the need. Haven't had any complaints nor seen any issues by not doing this test. I do pressure test with a spark plug test although you and the Tempest marketing department say that is not enough. I guess I will have to have an issue that proves me wrong.
    Steve Pierce

    Everybody is ignorant, only on different subjects.
    Will Rogers
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  14. #94
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    Quote Originally Posted by Steve Pierce View Post
    Guess I haven't seen the requirement nor the need. Haven't had any complaints nor seen any issues by not doing this test. I do pressure test with a spark plug test although you and the Tempest marketing department say that is not enough. I guess I will have to have an issue that proves me wrong.
    Apparently the slick mags require the resistance to be within limits or it will cause premature coil failure.

    Tim

  15. #95

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    Quote Originally Posted by astjp2 View Post
    So you are willing to providing your customers only half of the tests that are required for spark plugs? How much an hour do you charge that you cannot spend 3 minutes to check the resistance on 8 spark plugs in a cub? Its an easy check and I personally have found enough failures to continue. Oh and my work has 50 airplanes in their flight school, and 15 of them are Lycomings so I am seeing more use and abuse issue than I ever did with most private GA customers. Tim
    Please show me where a resistance check is required on spark plugs other than Tempest. Champion Aerospace disagrees with the requirement.

    From Champion Aerospace Service Letter SL74-20-001

    "It is our opinion that the 5,000 ohm service limit for aviation spark plugs, currently being published inmarketing literature by our competitor, is an erroneous and unsubstantiated limit. It is our opinion thatthis supposed limit was not selected as a result of any actual testing, but somewhat arbitrarily basedupon the inherent characteristics of the resistor design and the manufacturing tolerances provided tothem by their foreign supplier for spark plug core assemblies."

    You can read the whole SL here https://www.championaerospace.com/as...L74-20-001.pdf

    As far as my customers go, I'm fairly certain they keep coming back because they trust my judgement.
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  16. #96

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    I posted a link to the Taylorcraft website where I posted the Mils-pec on plugs...which has a requirement for the acceptable ohms for a plug to be published. I Guess that you didn't read the link? But hey, welcome to the 1980's

  17. #97

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    Quote Originally Posted by Wingwrench View Post
    Please show me where a resistance check is required on spark plugs other than Tempest. Champion Aerospace disagrees with the requirement.

    From Champion Aerospace Service Letter SL74-20-001

    "It is our opinion that the 5,000 ohm service limit for aviation spark plugs, currently being published inmarketing literature by our competitor, is an erroneous and unsubstantiated limit. It is our opinion thatthis supposed limit was not selected as a result of any actual testing, but somewhat arbitrarily basedupon the inherent characteristics of the resistor design and the manufacturing tolerances provided tothem by their foreign supplier for spark plug core assemblies."

    You can read the whole SL here https://www.championaerospace.com/as...L74-20-001.pdf

    As far as my customers go, I'm fairly certain they keep coming back because they trust my judgement.
    Champion has changed their tune since 2012...

  18. #98
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    Requirements aside, I would treat the resistance test as an optional test that can give useful info. I found an intermittent plug this way, and I suspect there are marginal plugs that pass the bomb test but would show up on the resistance test. And, if you're getting mag noise in the radio, this is a quick way to find the deficient plug.
    Make friends, because life isn’t fair.
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  19. #99
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    Quote Originally Posted by astjp2 View Post
    Champion has changed their tune since 2012...
    Champion no longer uses carbon pile resistors in their spark plugs but their technical rep told me that if a spark plug tests good on the pressure tester it is considered good. No requirement to ohm test. So does the mil spec on spark plugs require them to be ohm tested annually? The FAA calls out the requirements for testing an ELT but I have not seen one on spark plugs.
    Steve Pierce

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    Will Rogers
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  20. #100
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    NOW we're gettin' somewhere! Lol.
    Life's tough . . . wear a cup.
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  21. #101

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    If we had to maintain to mil spec, none of us could afford to fly. The FAA sets our standards. 43.13 has a section on spark plugs.
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  22. #102

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    Quote Originally Posted by Wingwrench View Post
    If we had to maintain to mil spec, none of us could afford to fly. The FAA sets our standards. 43.13 has a section on spark plugs.
    So you are saying that I can use grade 5 bolts instead of AN which is a Mil-spec? I realize that Diamond, Technam, and Czech us DIN hardware but we are speaking Merican here...

  23. #103
    www.SkupTech.com mike mcs repair's Avatar
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    Spark plugs

    question for SJ,
    is there a block user feature on here like on FaceBook???, so we don't ever have to see some users weird post for evermore??? makes facebook so much more enjoyable once you identify them...


    https://m.youtube.com/watch?v=cqk5of8LgLE

  24. #104
    wireweinie's Avatar
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    Holy crap, I think I pulled a muscle. Lol

    Web
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  25. #105
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    Quote Originally Posted by mike mcs repair View Post
    question for SJ,
    is there a block user feature on here like on FaceBook???, so we don't ever have to see some users weird post for evermore??? makes facebook so much more enjoyable once you identify them...


    https://m.youtube.com/watch?v=cqk5of8LgLE
    There is...


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  26. #106
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    AOPA article on the Champion spark plug issue...

    Read the article below with an open mind, and I suspect your thinking might change... I respect the folks on this forum tremendously, but Mike Busch lays out a simple and compelling case:

    One of the interesting quotes in the article is from the actual Mil Spec for aviation spark plugs (MIL-S-7886B), which states in part:
    "4.7.2 Resistor. Each spark plug shall be checked for stability of internal resistance and contact by measurement of the center wire resistance by use of a low voltage ohmmeter (8 volts or less). Center wire resistance values of any resistor type spark plug shall be as specified in the manufacturer's drawings or specifications." (emphasis mine)

    After experiencing horrible misfiring on two different aircraft whose mags, harnesses, and Champion spark plugs all passed the "conventional" tests (specifically including the "bomb" testing for the spark plugs), the "resistance test" found very high resistance in more than half of the Champion spark plugs in both plane's engines. In both the turbo-normalized IO-540 Lycoming (Commander 114) and the dirt-simple O-200 Continental (Citabria 7ECA), new plugs – ones that passed the resistance test – immediately resolved the misfiring issue.

    Oddly enough (yet not totally surprising), three of the "brand new, still in the box" Champion plugs failed the resistance test before they were ever installed. Ironically, this was just weeks before Champion released their redesigned plugs which eliminated the issue (by basically copying Tempest's design)... Oh, and my A&P told me Champion would NOT replace those "bad" plugs. He had to eat the cost... Maybe that's why he now stocks and recommends Tempest plugs?
    Jim Parker
    2007 Rans S-6ES

  27. #107
    Steve Pierce's Avatar
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    Doesn't make any sense, Champion Carbon pile resistor plugs will not pass the 5 ohm test ever, period.
    Steve Pierce

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    Will Rogers
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  28. #108

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    Quote Originally Posted by Steve Pierce View Post
    Doesn't make any sense, Champion Carbon pile resistor plugs will not pass the 5 ohm test ever, period.
    I have passed a lot of chamopion plugs for years, I can think of more failures for an open circuit than high resistance. And they all passed the pressure test. I also realize that most mechanics will not change their minds no matter what I say so you do what you feel is best and good luck.

  29. #109
    Steve Pierce's Avatar
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    Another tool in the tool box. When I have an issue I know where to go. I tried checking some carbon pile Champion plugs, didn't work. Are you telling me the old style carbon pile Champion spark plugs should pass the 5k ohm test as well?
    Steve Pierce

    Everybody is ignorant, only on different subjects.
    Will Rogers

  30. #110
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    Quote Originally Posted by astjp2 View Post
    I also realize that most mechanics will not change their minds no matter what I say so you do what you feel is best and good luck.
    Yea, delivery is everything. Thumping your chest and telling us we are doing it all wrong is the way to win hearts and minds.
    Steve Pierce

    Everybody is ignorant, only on different subjects.
    Will Rogers
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  31. #111
    AkPA/18's Avatar
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    Quote Originally Posted by astjp2 View Post

    It is funny to watch an owner's eyes when you ohm a plug and it is high and I take it gently over to the bench, place a rag over it and smash it with a 3lb hammer, that way it never goes back into the airplane...because if they cant afford a replacement plug, they shouldn't
    Please send any fine wires pre sledgehammer and I will environmentally dispose them.Will pay shipping.
    Thanks,
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  32. #112
    www.SkupTech.com mike mcs repair's Avatar
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    Originally Posted by mike mcs repair
    question for SJ,
    is there a block user feature on here like on FaceBook???, so we don't ever have to see some users weird post for evermore??? makes facebook so much more enjoyable once you identify them...




    There is...


    thanks, click the users name and find the option there

  33. #113

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    Quote Originally Posted by mike mcs repair View Post
    Originally Posted by mike mcs repair
    question for SJ,
    is there a block user feature ?

    There is...


    thanks, click the users name and find the option there
    I found it and used it just a short bit ago.

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