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Cadillac in an 83 Blazer.....

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by HankS, Sep 25, 2003.

  1. HankS

    HankS Registered Member

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    I am planning a 500 Cadillac motor swap. I have read most of the posts covering cad motor swaps. I have a few questions and would like to get some opinions from the gurus who have been down this road before...

    I want to build the ultimate go anywhere anytime truck, road, rocks, sand, mud, trails etc, etc... and make good gas mileage.

    1. bop th400, Why not just use this tranny? pros + cons
    2. T-case, What is the best behind this combo and why? Your opinions on doublers and underdrives as well.
    3. R&P gears, What is the best ratio for a 38 inch tire and the afore mentioned t-case. Remember, I want good (15mpg)gas mileage.
     
  2. BowtieBlazer

    BowtieBlazer 1/2 ton status

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    I want good (15mpg)gas mileage.

    If you get that mileage ever out of the caddi engine post every little thing you did...I'd only expect those numbers out of a highly modified truck running diesel

    good luck
     
  3. steelsoldiers

    steelsoldiers 1/2 ton status

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    I had a basically stock '76 500 in my '84 K5 for a while. I used the adapter plate to bolt it to my Chevy TH400. If you use a BOP TH400 you have to change the output shaft, which is OK if you are going to have the tranny rebuilt anyways. My 500 was about 98% stock and I only got about 7mpg with 3.73s and 35" tires. It sucked stopping at the pump that often. People used to give me $#!T about how my K5 would pass everything but a gas station. /forums/images/graemlins/rotfl.gif So, please don't expect 15mpg unless you are planning on 3.08s and 30" tires, even then, it'd be pushing it. Don't get me wrong though, the raw balls power was really nice. I enjoyed being able to light the tires up at will. To make a long story short, my oil pump gave out and the bottom end burnt up and now my 6.2L diesel is back where it belongs, getting 15mpg I might add. If you do this swap, rebuild your engine completely for reliability. I redid the top end on mine, but nothing else. Remember, even if the engine has relatively low miles, it still pushing 30 years old. Call Al at MTS and he'll hook you up with anything from mild to wild parts and swapping items too. Good luck. /forums/images/graemlins/thumb.gif
     
  4. HankS

    HankS Registered Member

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    Thanks steelsoldiers,

    I am planning on a complete teardown and rebuild. I will try to stay as close to stock tolerances as I can on everything, but I won't know until its torn apart. I'm also asking the Cadillac guys about fuel injection and any other tricks they have up their sleeve to get gas mileage out of it. The power will be there, whether or not I can build it Exxon card friendly is another story....
     
  5. tch777

    tch777 1/2 ton status

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    If you are really serious about fuel economy you have to get a tranny with over drive.

    Tim
     
  6. micah

    micah 1/2 ton status

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    [ QUOTE ]
    If you are really serious about fuel economy you have to get a tranny with over drive.

    [/ QUOTE ]

    I agree. I know there are alot of 700r4 haters out there, but I say if you want the mileage, you want a 700. Just spend the money on a well built tranny (700r4.com is where I got mine) and on a good tranny cooler (Summit has the B&M stacked plate for 50-60 bucks). With the OD tranny, you can go a lot deeper in your gear selection... like 5.13's if you're running corporate axles.
     
  7. boz42

    boz42 1/2 ton status GMOTM Winner

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    most of your caddy guys say a 700r4 will not live behind a 500. i don't know if it will or not.

    i too am planning this swap real soon. i will run a bop 400 & an ord doubler w/ 5.13's & 42's.

    no offense, but gas mileage is usually your last worry when u got 500 ci under the hood. big motors use lots of gas. /forums/images/graemlins/thumb.gif
     
  8. bpiccioni

    bpiccioni 1/2 ton status

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    [ QUOTE ]
    most of your caddy guys say a 700r4 will not live behind a 500. i don't know if it will or not.


    [/ QUOTE ]

    Why not consider a more reliable 4 speed Automatic, like a 4l80e? They arent cheap, but money must be no object if youre willing to feed a 500! /forums/images/graemlins/laugh.gif
     
  9. 84_Chevy_K10

    84_Chevy_K10 Banned

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    How about just a cheaper automatic, like a TH 400, and use a higher gear in the axles. If you want to crawl, get yourself a doubler, it'd still be cheaper than the 4L80E and have a low cruise RPM to boot.

    I say you run a TH 400 combo (may have to put a 4wd tailshaft in a BOP 400 to make this setup work) use 4.10 or 4.56 gears and run a doubler if you have the need to crawl. I still think you're dreaming with that kind of fuel mileage, though. My 350/465/205 combo with 4.10s and 38s wouldn't even touch that kind of mileage, even on the highway.
     
  10. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

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    [ QUOTE ]
    Remember, I want good (15mpg)gas mileage.


    [/ QUOTE ]

    BAAHHHAAA! /forums/images/graemlins/rotfl.gif /forums/images/graemlins/laugh.gif Where did you get that idea! I have a pumped up 406, 4.10's, 35"boggers,9"lift, AND a 700R4. I get about 6mpg in town and 10mpg MAYBE on the freeway! I drive it like I stole it through town though. /forums/images/graemlins/tongue.gif /forums/images/graemlins/rolleyes.gif Guarranteed that you will get just as bad or worse with 38's,th400, and a very thirsty 500. A stock carburated 305 K5 would have trouble getting 15mpg on average. shoot I only got about 14 or so on the highway at 60mph when I bought my K5 and was still TOTALLY stock with a 350! /forums/images/graemlins/deal.gif
     

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