Properly gapping new NGK Iridium Spark Plugs

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Thread: Properly gapping new NGK Iridium Spark Plugs

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    SupraForums Member YoudLse's Avatar
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    Properly gapping new NGK Iridium Spark Plugs

    I just got my new NGK Iridium spark plugs today from MVP...

    What gap would you go with for the following mods... Intake, Catback, Test Pipe, 11.5 PSI? I know that .032 is stock, what would you recommend?

    Also, how do you gap your plugs accurately with one of those crappy disc shaped tools? Is there something better? I would like to have accuracy to the millimeter... My idle has been crap ever since the engine swap about 6 months ago. I have tried swapping the coil pack and wires from my other Supra.. Please help.
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  3. #2
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    I would leave the plugs alone, unless the ones in there now are bad.
    Same with the gap.
    I use a wire type gap adjuster good accuracy.
    So the idle is bad. Is the idle speed too slow? Does it rise and fall? Any more info would help.

  4. #3
    SupraForums Member YoudLse's Avatar
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    Originally posted by shmuggums90
    I would leave the plugs alone, unless the ones in there now are bad.
    Same with the gap.
    I use a wire type gap adjuster good accuracy.
    So the idle is bad. Is the idle speed too slow? Does it rise and fall? Any more info would help.
    Yes. The idle is low, around 500 RPM, after it warms up. Also, I can hear the car constantly misfiring about once or twice every second.

    With regard to the new plugs, are you saying I should just leave it at whatever the new plugs are already gapped at? According to the disc guage, they are at about .037 gap right now.

  5. #4
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    Re: Properly gapping new NGK Iridium Spark Plugs

    Originally posted by YoudLse
    I just got my new NGK Iridium spark plugs today from MVP...

    What gap would you go with for the following mods... Intake, Catback, Test Pipe, 11.5 PSI? I know that .032 is stock, what would you recommend?

    Also, how do you gap your plugs accurately with one of those crappy disc shaped tools? Is there something better? I would like to have accuracy to the millimeter... My idle has been crap ever since the engine swap about 6 months ago. I have tried swapping the coil pack and wires from my other Supra.. Please help.
    I was told you can't nor should you try to gap Iridium plugs. They are suppose to last like 250k miles. Electrode made from material from meoterites <[sp]

  6. #5
    Red Rider turbo_smallblockchevy's Avatar
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    the electrode is very fine and need not be gapped i was told. if it is missing check your plug wires and make shur there was no oil in the plug galley when you did the job as that seems to interfear with operation

    iridium is found here on earth also
    Treasure coast imports!

  7. #6
    Supra Fan
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    My NGK Iridium XI spark plugs came out the box gapped at .028. I re- gapped them to .031. I havent used them yet so i dont know how they will work out.

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    wastegate hose is pulled chevyeater-on-sf's Avatar
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    The round wire type is the best gapping tool. Just don't bust the center electrode off. Every spark plug should be gapped before installation, no matter what it is made out of, the spark still has to jump the gap. Gap them to the stock setting, should be fine for your mods.

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    ngk plugs are pre gapped

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    Professional White Man hoser813's Avatar
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    Id say you might want to invest in a feeler gauge. They arent that expensive, and it will help you with many different engine clearance issues, and also spark plug gap. And I hear that copper plugs are better for FI than iriduim.

  11. #10
    SupraForums Member YoudLse's Avatar
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    Thank you all for your replies. I really appreciate them.

    Some feedback on the NGK Iridium's...

    I installed them using the factory pre-gapped setting of .037, according to my disc-shaped gapping tool. I torqued each plug to approx. 13 ft/lbs using a torque wrench.

    Before installation, I had constant misfiring and stalling after decellerating for a stop light.

    After the install, the idle was smooth as butter and I felt more power from the car (to be expected with better ignition).

    I would highly recommend the NGK Iridiums to any MKIII Supra owner, if you want an awesome plug. I have tried the Autolite 3923 Copper plugs gapped to .032, and didn't have great success with them.

    And thank you MVP for quick shipping!

  12. #11
    Supra Fan
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    Originally posted by shmuggums90
    ngk plugs are pre gapped
    Yes but not pre-gapped to the right specifications

    you need to gap them to .031
    - 1990 Black turbo/targa/5spd SOLD(May 2006)
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    SupraForums Member sneakypete's Avatar
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    You arent supposed to gap platinum or iridium plugs. They should be purchased pre-gapped. You risk breaking off the side electrode when you gap platinum or iridium. Thats the last thing you would want in your combustion chamber.
    -pete

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    Originally posted by sneakypete
    You arent supposed to gap platinum or iridium plugs. They should be purchased pre-gapped. You risk breaking off the side electrode when you gap platinum or iridium. Thats the last thing you would want in your combustion chamber.
    -pete
    Dont know who told you that . Like I said 2 replies ago: I measured my ngk iridium xi's out the box and they were gapped at .028. thats why i gapped them to stock(.031).

  15. #14
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    NGK plugs are pregapped, just buy the correct ones and your set...

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    United States of America isnms's Avatar
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    Its recommended Not to regap iridiums.
    http://www.spark-plugs.co.uk/pages/specials/Denso.htm
    center of the page - "**DO NOT REGAP IRIDIUM SPARK PLUGS!!** "
    Last edited by isnms; 01-19-2005 at 09:38 AM.

  17. #16
    Stormcock approves Shlongor's Avatar
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    Yeah, trust the pregap. Just like those NGK plugs I bought that required something like a 13/16 socket, which as you may know, will never fit down in the spark plug holes...

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    Sorry guys :( I had to!

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