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XJ 550 replacement coils, out of spec

Discussion in 'XJ Technical Chat' started by a100man, Jun 10, 2024.

  1. a100man

    a100man Well-Known Member

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    Hi Folks

    I bought soem new coils from a UK supplier I used before without issue
    but they arrived too small physically but also out of spec for primary/secondary which I measured
    as 3.9 Ohms and 15KOhms respectively. To try them I woulsd also need to cut off the special (primary) connectors from the OEM coils.

    The old coils in fact measure good but I had trouble hot starting recently and observed a weak yellow spark so I thought I'd try new.

    Should I gamble on trying teh new ones with those specs? I've also contacted the supplier in case wrong items were sent.

    Cheers
     
  2. a100man

    a100man Well-Known Member

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    BTW does anyone know .. was there ever a 550 model that used coils with a 90mm bolt hole spacing?
     
  3. chacal

    chacal Moderator Moderator Supporting Vendor Premium Member

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    No. Those are closer to XJ700 coils, and the 3.9 ohms primary resistance is really too high (they'll probably work, but may not do much for the longevity of your TCI box).
     
  4. a100man

    a100man Well-Known Member

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    Thanks Len. Supplier is trying to assert the higher [primary will deliver a 'better spark' I'm dubious and also concerened over long term affects of the TCI.
    They will be returned I think.

    Cheers

    James
     
  5. Minimutly

    Minimutly Well-Known Member

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    Higher resistance gives less current, which potentially should give a smaller spark...
    And an easier life for your tci, not a harder one. Best tomatch the original as closely as possible, to get best spark.
     
  6. a100man

    a100man Well-Known Member

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    Yeah opted to return thes eand get some 3 Ohm/14kOhm ones. Anorther 20 quid but still cheap enough I hope.
     

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