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  1. #1

    Default 2.8l to 3.4l engine swap

    1985 GMC S15 2.8l v6 2wd Ext cab auto.

    I have decided to just go ahead and go with the 3.4l V6 engine because I've read that it is a direct fit. My only issue now is I have an automatic and would prefer to have a 5-speed manual. Does anyone know if it will be a direct fit or if any modifications will be needed?

    I'm also under the assumption that everything from my 2.8 will bolt up to the 3.4. Alt, Intake, A/C
    Any and all help will be greatly appreciated.
    Thanks! =-=-Chris=-=-
    Last edited by chriscolehawk; 04-16-2014 at 01:23 PM.

  2. #2
    Sr. Apprentice Gramps43's Avatar
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    I don't think they are compatible, the 2.8 is a 60 engine and the 4.3 is a 90 in the SBC family of engines. As for as accessories are concerned the Alt, A/C and P/S should work with the appropriate 4.3 brackets.

    Disregard the above, me BOO-BOO.
    Last edited by Gramps43; 04-19-2014 at 05:48 PM.
    Gramps

    20 yrs. USAF

  3. #3

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    I don't think your auto tranny will bolt to the 4.3 bell housing, I think the bolt hole pattern is different.
    Ray

    '09 Avalanche LTZ - Black
    '05 Envoy XL (sold)

  4. #4

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    A 3.4 will work. A 4.3 will work if you get different motor mount perches. You will need another tranny, harness, computer. I did this swap with mine except I started with the 2.5. You will need a harness/computer regardless. A 2.8 v6 5speed will bolt up to the 3.4, but I believe you will need another 5 flywheel. That I can not be certain about,
    Chuckie!!!


  5. #5

    Default

    Quote Originally Posted by BurbanMan View Post
    A 3.4 will work.,
    My bad, I said the bell housing would be different, the 3.4 should be the same, I was thinking and typing 4.3


    EDIT: is it just me, or is there something strange about the heading on the 1st post.

    When closed it shows 2.8 and 4.3, but when opened, it shows 2.8 and 3.4. What's with that?

  6. #6
    Sr. Apprentice Gramps43's Avatar
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    Actually no there's nothing wrong, but there is a problem with my eyes. The 3.4 is the last of the 60 V6's so everything from a 2.8 and a 3.4 should swap.

  7. #7

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    Quote Originally Posted by Gramps43 View Post
    Actually no there's nothing wrong, but there is a problem with my eyes. .
    No gramps, you made the same error I did. It reads 4.3 when the thread is closed and it reads 3.4 when the thread is open.

  8. #8
    Sr. Apprentice Gramps43's Avatar
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    Damn I wish I could make up my mind. 8~{)) Where is the guy who started this mess when you need him. When he does show up I'm going to rumble all over hi butt. 8~{))

  9. #9

    Default

    Sorry for all the confusion. When I made the post I typed 4.3 instead of 3.4. I went back and edited it.
    Now, heres a few questions..
    My truck is not computer controlled.. (I assume because there is no check engine light.) Am I right?
    Also the 2.8 has the mechanical fuel pump and is carburetor. Does the fuel pump mount the the 3.4?
    Last edited by chriscolehawk; 04-19-2014 at 08:56 PM.

  10. #10

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    Quote Originally Posted by chriscolehawk View Post
    Sorry for all the confusion. When I made the post I typed 4.3 instead of 3.4. I went back and edited it. Now, heres a few questions.. My truck is not computer controlled.. (I assume because there is no check engine light.) Am I right? Also the 2.8 has the mechanical fuel pump and is carburetor. Does the fuel pump mount the the 3.4?
    the 3.4 is fuel injected. You will need to install a computer and wire it all up.

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