Can new spark plugs make a noticeable difference in performance?

Discussion in 'Maintenance Bay' started by Lndwarrior, Jun 14, 2019 at 12:00 AM.

  1. Lndwarrior

    Lndwarrior Pre-takeoff checklist

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    Can they? If so, how significant?

    TIA
     
  2. Bill Watson

    Bill Watson Pattern Altitude

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    Yes, depending on how cruddy and worn the old ones were.

    No, but noticeable if things were overdue.

    Do note that when plugs are changed, the timing is usually checked as well so there’s that.


    Sent from my iPad using Tapatalk Pro
     
  3. Let'sgoflying!

    Let'sgoflying! Touchdown! Greaser! PoA Supporter

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    I have not noticed a difference between new and “old/worn, but functioning” plugs.
    They are either ‘on’ or ‘off’ for me.
     
  4. Checkout_my_Six

    Checkout_my_Six Final Approach

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    depends....how bad were the old ones?o_O


    but, doubtful if the old ones were working.
     
  5. MooneyDriver78

    MooneyDriver78 Pattern Altitude

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    Especially on starts...


    Tom
     
  6. Doug Reid

    Doug Reid Pre-takeoff checklist

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    Noticeable improvement going from rem40e to rem37by in my Jacobs engine. Less prone to fouling . Unless a plug was defective, I never noticed any difference when replacing an old rem40e with another new rem40e in my Bonanza.
     
  7. Unit74

    Unit74 Final Approach

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    A swap to fine wires was noticeable.
     
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  8. SoCal RV Flyer

    SoCal RV Flyer Pattern Altitude

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    I just changed out my Champion REM 38E massive electrode plugs for the Tempest equivalent, at 330 Hobbs hours of use. Very noticeable improvement in ease of starting. Checked magneto timing, and right mag was off only 1 degree from 25 BTDC.

    I didn't bench-test the old plugs, but I noticed the Champions were the old design (slotted contact on top; new, improved design is smooth) that have a history of developing high resistance.
     
  9. Dan Thomas

    Dan Thomas Final Approach

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    I used to replace all the REM38/40 plugs with the REM37BY (better: UREM37BY) plugs in any engine that had them listed as alternates. Those plugs are indeed fouling-resistant, and I think they actually fire more consistently because the electrodes are sticking a little farther into the cylinder and the air/fuel mixture. Sometimes I've wondered if the exhaust gases all get scavenged out of the deep wells in the 38/40 plugs.
     
  10. Clip4

    Clip4 En-Route

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    Noticeable on run up.
     
  11. SkyDog58

    SkyDog58 Touchdown! Greaser! PoA Supporter

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    Only if you replace the gaskets as well.

    :happydance: