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Thread: replacing spark plugs

  1. #1
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    replacing spark plugs

    I'm about to change my spark plugs for the first time. My haynes manual specifies a certain number that I have to set my torque wrench to (15nm IIRC). Do I really need a torque wrench to do this or would just making sure that they are tight but not overtight do the trick ?
    Torque wrenches are really expensive and I don't really want to spend that kind of money on something I'd hardly use.

  2. #2
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    You should be able top pick up a torque wrench for ~20 euros .... http://www.screwfix.com/app/sfd/cat/...46124&id=18289

    However, may not be necessary as their are rules-of-thumb for most vehicles/plugs - eg "finger tight and then a quarter turn". What's the car and plug type ?
    "A woman without curves is like a road without bends, you might get to your destination quicker but the ride is boring as hell'

  3. #3
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    Hmm, 20 isn't much, I've probably been looking at really high end ones then. All the prices I saw were 100+ euros.

    It's a Clio 1.6 16V, and the Haynes manual says: Bosch RFC 50 LZ 2E spark plugs. 0,9mm gap.
    All 4 plugs are powered by their own pen-type coil. Not a single coil for all cylinders. If that matters.

    I just checked the manual and it says between 25 and 30nm

    Another question: if I buy these plugs will I still have to adjust the gap or will they come pre adjusted ?

  4. #4
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    Id presume they are going into an Alloy head, be careful finger tight the 1/4 of a turn. Id check plug gaps with a feeler gauge to be on the safe side
    HTH
    SA IPRA cars 15, 25, 51 & 77
    Sharperto Racing IP Corollas
    http://www.sharperto.com.au/

  5. #5
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    Quote Originally Posted by Lagonda
    It's a Clio 1.6 16V, and the Haynes manual says: Bosch RFC 50 LZ 2E spark plugs. 0,9mm gap.
    http://www.boschautoparts.co.uk/pcPlug11.asp?c=2&d=1
    Another question: if I buy these plugs will I still have to adjust the gap or will they come pre adjusted ?
    They will come adjusted, but as advised ..... check them
    "A woman without curves is like a road without bends, you might get to your destination quicker but the ride is boring as hell'

  6. #6
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    Thanks, I'll go out tomorrow to buy some spark plugs.

  7. #7
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    Quote Originally Posted by Matra et Alpine
    eg "finger tight and then a quarter turn". What's the car and plug type ?
    Thats not a brilliant rule, some only turn 1/16th of and others 2/3rds.

    If you buy NGK plugs they have a couple of diagrams on the side of the box that tell you how much to tighten the plug just make sure you choose the right one
    PPC - Put a V8 in it!

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    Quote Originally Posted by h00t_h00t
    Thats not a brilliant rule, some only turn 1/16th of and others 2/3rds.
    That is NOT a "rule" it was eg "for example" not ie "therefore it is".

    The link provided gave the Bosch recommendation

    1/16th is for a shoulder rather than washer seal plug.

    If you buy NGK plugs they have a couple of diagrams on the side of the box that tell you how much to tighten the plug just make sure you choose the right one
    Yep, as do most and hence why asked WHAT plug he had.
    You can't rely on different plugs for the same engine having the same rule of thumb as some compressible washers are stronger than others.
    "A woman without curves is like a road without bends, you might get to your destination quicker but the ride is boring as hell'

  9. #9
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    Well that about nails this thread...Get the right plugs for your application....Read the box or go to their website for the installation info...Check your plug gap...And don't crack them when you install them and all is fine.

    Or do what some mechanics do that I have seen. Take them out of the box, screw them in tight, and test drive them hard for misfires.
    Last edited by revetec; 02-07-2007 at 06:21 PM.

  10. #10
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    When I cleaned up the spark plugs in my beetle I just used a wrench and socket set, shouldn't I have done that?
    I did it till it was almost tight and then loosened it off slighty, its harder to explain but I just did it till it felt right. If you know what I mean!

  11. #11
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    Loosened off isn't best.
    If it has compessible washers then you compresed them adn by backing off have increased the chance of loose plugs/blow-by, equally os if was a taper seal.

    What did you mean by "almost tight" - finger or wrench ?

    I'd recommend go back adn do it properly with a torque wrench, you can't rely on 1/4 turn etc as the washer is compressed.

    Doing it by "feel" is fine after 10 years experience
    "A woman without curves is like a road without bends, you might get to your destination quicker but the ride is boring as hell'

  12. #12
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    Quote Originally Posted by Matra et Alpine View Post
    Loosened off isn't best.
    If it has compessible washers then you compresed them adn by backing off have increased the chance of loose plugs/blow-by, equally os if was a taper seal.

    What did you mean by "almost tight" - finger or wrench ?

    I'd recommend go back adn do it properly with a torque wrench, you can't rely on 1/4 turn etc as the washer is compressed.

    Doing it by "feel" is fine after 10 years experience
    Fair point, im no expert lol
    my dad said he would check it all over first though and he has had about 20 years experience so it'll be all good im sure!

  13. #13
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    Quote Originally Posted by tuk3410 View Post
    Fair point, im no expert lol
    my dad said he would check it all over first though and he has had about 20 years experience so it'll be all good im sure!
    To be sure i would have replaced the old ones with these new technology ones..
    Link!!
    I switched to these once some months ago and my car have never worked better!!

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