500ci swap into a 79 Eldo, do-able?

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500, 472, 425, 368 Discussion, 500ci swap into a 79 Eldo, do-able? in Cadillac Engine Discussion; I have a chance to pick up a 71 Eldorado 500ci complete w/trans for a couple hundred. Im wondering how ...
  1. #1
    seok's Avatar
    seok is offline Cadillac Owners Member
    Automobile(s): 1995 Deville 4.9, 1979 Eldo Biarritz 5.7 Carbed!!
    Join Date
    Nov 2010

    500ci swap into a 79 Eldo, do-able?

    I have a chance to pick up a 71 Eldorado 500ci complete w/trans for a couple hundred. Im wondering how much work would it be to
    plant it into a 79 Eldorado with the Olds 350? Is it a direct swap or is there way to much work involved, and if so, what?
    looking for any info from someone who's put one in a small Eldo before. Thanks.

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  3. #2
    BRUCE ROE is offline Cadillac Owners Fanatic
    Automobile(s): Eldorado
    Join Date
    Jun 2009

    500ci swap into a 79 Eldo, do-able?

    The 80-81 Eldo had the 368 engine, which is the same big block
    as a 500. You need to get all the pieces from those models to do
    an engine swap. You can even change to a 76 500 ECU and keep the
    79 Eldo fuel injection. Might need slight tuning, I can advise on this.

    A far simpler swap is an Olds 403 small block into the 79. Just
    use a 425 ECU, or I'll help tune the stock ECU. With a 2.73 axle
    change and a free flowing exhaust, this will burn plenty of rubber.
    I used a 76/77 iron intake manifold with the larger throttle body.
    One problem was the oil filter.

    Don't expect a lot of life from the TH325 trans driven by a 500
    engine. If you plan to swap in the TH425 trans & final drive, you
    have a major project ahead. Moving things for clearance, half
    shaft adapters, custom parts everywhere. But you can get the
    advantage of switch pitch and use a POWER DRIVE 65:57 chain
    set to get a more economical 2.40 overall final ratio. And it
    won't break with the big engine. That is what is in my 79 Eldo
    and a 403. See pictures on sub albums of my PHOTOBUCKET.


    (that is a lower case "L"71, not an upper case "i"71)

    click on a Sub-Album
    click on a picture to enlarge + explanation

    Bruce Roe CLC # 14630

    815 234-8039

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