Is it safe to gap used spark plugs, or should you only gap brand new spark plugs?

13 Answers

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  • zipper
    Lv 6
    7 months ago

    Sure is a good thing to do!  I worked on a lot of old tractors, cars and so on, if the plug was still good I always re gaped them!

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  • arther
    Lv 5
    8 months ago

    its a waste of time just replace the plugs the gap will be correct when you get them out of the box.

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  • Anonymous
    8 months ago

    Just buy new spark plugs and gap them. I put new plugs in, every other oil change.

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  • 8 months ago

    I wouldn't mess around regaping old spark plugs. Just put a set of Iridium spark plugs in. They come pre-gaped and last for 100,000 miles..

    Go to advance Auto and ask what brand OEM spark plugs came from the factory.

    Source(s): Mitsubishi Master Tech
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  • 8 months ago

    Yeah. In the old days, we had a little bench top sand blaster for the plugs. Blast them, blow them clean with compressed air, gap 'em and screw ;em back in. They wore out quicker with leaded gas.

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  • 8 months ago

    Conventional plugs can be cleaned, filed square and gapped, until they're too worn out for there to be enough electrode to gap. New platinum or Iridium plugs should not be gapped, and if you find them to be mis adjusted, exchange them where you bought them for plugs that are not damaged.

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  • Anonymous
    8 months ago

    Safe.  Obviously, you have NEVER done this before so find out how to do it.

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  • Anton
    Lv 6
    8 months ago

    New, used, who cares -- when you have the plugs out, you should check/re-gap them.

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  • Robin
    Lv 7
    8 months ago

    most modern spark plugs are surface discharge

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  • 8 months ago

    Safe in what way? There is no danger to life in gapping old spark plugs.

    The may not work as well as new ones but that should not result in any danger unless all four stop working simultaneously.

    • Drizzy7 months agoReport

      Danger as in heat cycled metal being bended. Wasn't sure if that was ok or not.

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