99 Silverado 4.3 to V8 Swap Question

Discussion in 'The Garage' started by 2High4U, Jan 7, 2006.

  1. 2High4U

    2High4U 1/2 ton status

    Aug 20, 2005
    Likes Received:
    Felton Pennsylvania
    When my motor gives out or maybe even before I want to know what all envolved in changing it.

    My questions.

    1. will the computer out of a v8 truck hook up to the factory harness or do I have to pull the harness out of the other truck? ( is the harness sepreate from the rest of the main harness? )

    2. Is it legal to change a V6 to a V8 due to immisions and inspection?

    3. should bolt right up to the tranny right?

    If all this is possible then it shouldnt be a big deal to swap it out.

    Just curious I dont want to end up starting this project and then be screwed because of it not being legal or being stuck on something that I didnt have plans on.
  2. dave_90_blazer

    dave_90_blazer 1/2 ton status

    Jan 1, 2004
    Likes Received:
    Melvindale, Michigan
    ok, being a 99, you want to go from a vortec 4.3, to a vortec 5.7, right?

    well, the computer is pluged into the engine harness, and you need to change/modify the harness for the engine, so..........

    but yes, the PCM will plug in, but you are missing a few wires, and yes, the trans will be fine

    as for legality and emmisions, yes and yes, as long as the V8 has all the emissions stuff on it that it would have had stock, and it needs to be the same motor that the truck would have had(vortec 5.7, not TBI, ect.)

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