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Thread: Denso plugs

  1. #1
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    Denso plugs

    Another dumb question from a newbie here - I see a lot of you have Denso plugs as mods.
    I got 3 q's for you:

    1)What are the advantages here ?
    2)How easy are they to change ?
    3)Would their installation upset factory warranty ?

  2. #2
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    Re: Denso plugs

    Originally posted by usgecko
    1)What are the advantages here ?
    Dennis said so!!
    MOK


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  3. #3
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    1) Although they add a few HP by themselves, they're really part of a "package" with the chip (or re-flashed ECM) and a cooler thermostat, that allow Dennis's programming to work at its best...

    2) They are VERY easy to change.

    3) ANYTHING you do to this car "may" void the warranty, if your dealer chooses to pursue that line...but the dealer would be more likely to void it for having a chip than for having the plugs...this is a very gray area; for instance, some dealers will happily install the 4.10 gears and honor the warranty, but some absolutely refuse (like mine )...
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  4. #4
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    Gap and torque specs for Densos?

    I just ordered a set of Denso IT-22s from Reinhart Automotive (two steps colder--Dennis said that it'll be fine for my N/A Marauder) instead of the IT-20s since I plan on getting a supercharger later this year anyway. I'll be getting the Densos and the 180° thermostat next week to complement my recent dynotune from Jerry. I just have two questions . . .

    1. Are the Densos pre-gapped? If not, what gap?
    2. What is the torque ft.lb. spec for wrenching the plugs?

    Thanks.

    2003 Mercury Marauder 300B, matte-black, S55 taillights.
    B&M transmission/Precision Industries TC; Eibach-lowered; Addco rear anti-sway; Metco rear control arms; Steeda UDP; 180° 'stat.

  5. #5
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    Hello . . . Anyone?

    2003 Mercury Marauder 300B, matte-black, S55 taillights.
    B&M transmission/Precision Industries TC; Eibach-lowered; Addco rear anti-sway; Metco rear control arms; Steeda UDP; 180° 'stat.

  6. #6
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    Post

    I think everyone must be in Hershey
    2003 Marauder, 300A, Black/Dark Charcoal
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    2004 DTR/Dark Charcoal,
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  7. #7
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    I put my denso's in just before my powertune.Make sure you use alittle antiseize on the threads,just alittle.They come pregapped.I put my old one back into the Denso boxes.You'll know when you remove the old ones how much force you"ll need to put the new ones in.Make sure your spark plug socket is secure to your extension you won't believe how far in the plugs are or how long the spark plug boot is.
    PS You don't heed alot of force just make sure you hand start them and don't be in a hurry.
    Last edited by chapel1; 10-18-2003 at 02:50 PM.
    2003 (#867 of #7839) 300A Marauder
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  8. #8
    Torque?,... I asked Dennis this question when I bought them. He said "just snug them down."

  9. #9
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    Thanks, guys.

    I finally found an old post from Bunny, and she said it's "11 ft.lbs." The Denso box says a "1/16 turn" after it's tight for "taper-seat" plugs, which apparently these are. Someone else posted a Ford-recommended gap spec of 0.052"-0.056" for non-Denso, Motorcraft factory plugs. Due to the significant design difference between the two makes of plugs, that spec may not necessarily be directly applicable to the Densos, I'm guessing. But I know you're really not supposed to gap them manually because you run the risk of damaging the electrode. Dennis Reinhart made an explicit post NOT to gap the Densos. After visual inspection with a gap gauge, the Densos I received from Dennis looked very close to 0.050" as delivered, and I'm leaving them that way.

    Thanks, chapel1, for the tip about using anti-seize. Got some Permatex anti-seize and will use very sparingly. I found an old thread about the "dangers" of using anti-seize--the thread was split whether you should use it or not. I'm still going to use it--but an extremely light application.

    So, to summarize [edited to include RF's Denso information]:

    Spark Plug Gap and Torque Specs for Denso Iridium Plugs:

    Denso IT-20 [1-step "colder" for normally aspirated engines]
    Denso IT-22 [2-steps "colder" for supercharged engines]

    Torque: 11 ft.lbs. (1/16 turn for taper-seat or 7-15 ft.lbs., according to Denso. I found 11 ft.lbs. to "feel" just right).
    Gap: Denso recommends 0.050" gap; Ford 4.6L spec. for factory Motorcraft plugs 0.052"-0.056"; however, although Dennis Reinhart does not recommend regapping the Densos--it's your decision to regap or not (although, if I were to do it again, I would attempt to CAREFULLY regap to Denso's spec of 0.050").
    Anti-seize: No definitive recommendation (anti-seize not applied to factory plugs). Personally, I did apply anti-seize.
    Electrolyctic grease: applied to insulator and inside of boot as indicated by Permatex directions (electrolyctic grease is present on factory boots).

    Just re-editing this post after installation. Factory plugs' gap were dead on at about 0.052" upon inspection after removal. The Denso IT-22s appeared to be much tighter than that, at perhaps, 0.040" but I still left them as is, and did not attempt to readjust the gap simply because I just knew I'd ****** up at least one of the plugs!
    Last edited by studio460; 10-24-2003 at 05:48 AM.

    2003 Mercury Marauder 300B, matte-black, S55 taillights.
    B&M transmission/Precision Industries TC; Eibach-lowered; Addco rear anti-sway; Metco rear control arms; Steeda UDP; 180° 'stat.

  10. #10
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    'Shooter:

    I think you've summarised it pretty well...

    LML: maybe that should be in the FAQ...?
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  11. #11
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    I

    gapped them to Ford spec.....didn't brake nuthin.....and the car runs great......and ya don't need any torque spec. Ya just turn em til ya feel em stop.

  12. #12
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    Well, I need a torque spec, since the last time I torqued a spark plug in an aluminum engine was 1978! I have NO IDEA how much is too much!

    2003 Mercury Marauder 300B, matte-black, S55 taillights.
    B&M transmission/Precision Industries TC; Eibach-lowered; Addco rear anti-sway; Metco rear control arms; Steeda UDP; 180° 'stat.

  13. #13
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    No offence,

    but you don't need to overthink this one. it's a piece of cake. I do fully agree w/the recommendation to use the anti-seize compound on the sparkplug threads. That's needed because of the metal of the plugs being steel, while the cylinder heads that the plugs are being threaded into are aluminum. I'm an aircraft mechanic, and at my workplace whenever we install any hardware that is of a different metal than the parent material that it's being installed into, we use a zinc chromate type primer on the threads to prevent corrosion. When dissimilar metals stay in contact w/eachother for awhile, there's a tendency for a chemical reaction to take place that will cause corrosion.

  14. #14
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    None taken! It was your post on the other Denso thread that I stole the gap spec from! Although I actually agree with your post on the other thread, I hesitated to regap because I'd thought maybe the gap spec may be slightly different for the Densos than the one specified by Ford for the Motorcraft plugs due to the differences in design. I had planned to regap to 0.052" just like you said in your post, but I just knew my clumsy hands would've ******ed up the darn electrode! Good to know about your use of anti-seize compounds on aircraft applications.
    Last edited by studio460; 10-23-2003 at 05:40 AM.

    2003 Mercury Marauder 300B, matte-black, S55 taillights.
    B&M transmission/Precision Industries TC; Eibach-lowered; Addco rear anti-sway; Metco rear control arms; Steeda UDP; 180° 'stat.

  15. #15
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    Yeah,

    I can get pretty fussy while working on my cars. The times when I've worked w/my brother on these car projects, I drive him nuts because I tend to be very methodical too. But in my efforts to pay attention to detail, my experience w/working on Helicopters (I work at Sikorsky Aircraft) sometimes comes in handy since any aircraft has to be built more carefully and w/tighter quality control than a car does. And incase the reason for that isn't obvious, then I'll state that if there's a mechanical failure due to workmanship on a car which effects driveability or causes the engine to misfire or shut down, then the end result would usually be no worse than the driver of the car in question to be stranded on the road and have to walk home. But if it's an aircraft and there's a similar mechanical failure, the pilot and passengers will die.

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