NEEDED: Lots of info on doing a 500 caddy swap....

Discussion in 'The Garage' started by y5mgisi, Oct 9, 2004.

  1. y5mgisi

    y5mgisi 1 ton status

    Aug 11, 2002
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    Portland Oregon
    Well i picked up a 500 caddy motor for the burb(1978) So i need to no what problems im going to run into and how you did your motor mounts and the trans adapter(th350) The truck origanily had a 400. So i need lots and lots of pics and lots of FYI's so let me know what you got. /forums/images/graemlins/ears.gif
  2. BranndonC

    BranndonC 3/4 ton status

    Mar 18, 2002
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    Anaheim, Ca
    i dont have mine in yet, or bolted to a tranny, but i got my "universal mounting kit" and "transmission adaptor plate" from /forums/images/graemlins/thumb.gif
  3. 84gmcjimmy

    84gmcjimmy 1 ton status

    Dec 3, 2003
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    might want to do a search under Kert (cybrfire) he is in the process of putting one in his rig right now.
  4. cybrfire

    cybrfire 1 ton status Vendor GMOTM Winner

    Dec 15, 2002
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    Yep, putting one in sometime very soon.

    First off, your motor mounts will have to be relocated forward approximately 5". I don't know this measurement for fact other than tons of research on the internet.

    For the trans there are a few options.

    First you can put a Buick,old,pontiac (BOP) 400 behind it with a chevrolet tailshaft swapped into it to mate to your desired transfercase.

    Second, you can buy an adapter plate. Lots of places sell them. Summit, Jeg's, This allows you to simply bolt on your chevy transmission.

    Thirdly, You can buy and ultra bell which has both bolt patterns. Cut off your bell housing and install this one. Do a search in the garage under ultra bell. New post on this subject. Also do searches on Caddy and Cadillac. More info there.

    Exhaust will have to be addressed. Apparently there are some headers available for the swap that fit right on. Or there is a flange kit you can buy and then alter some chevy big block headers to work with that.

    If yours is a 500, It's most likely that it has a front sump pan and pickup tube. This will not clear your engine crossmember. So you will need a different pan and pickup tube. Check for this.

    Upper radiator hose won't work.
    Lower radiator hose, Maybe.

    I'm sure there is more but can't think of any off the top of my head. The ususal transplant woes. Linkages and such.

    Enjoy the torque. Remember when you choose gearsets with this type of engine keep the rpm's low. These beasts live well under 1800 rpms.

    Weight as per internet research splits the differnce from small block to big block.

    Also reports of better mileage with the big caddy. Most likely due to keeping the rpms lower and the engine creating the torque to still move you down the road.

    Plan on needing a good transmission. 400 turbo is a good choice in the automatics. Some people claim a professionally prepped 700 will hold up, Lots of people that deal with this directly disagree. I for one have not tried it. If it would it would be an excellent choice. Or anything with an overdrive would work well. Usually a lower first and then of course lower cruising rpm's are just what the doctor ordered.

    OK, rambling. got to go.

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