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TBI 454 into a 78K5

Discussion in 'The Garage' started by Corey 78K5, Mar 1, 2004.

  1. Corey 78K5

    Corey 78K5 1 ton status

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    What kind of problems might I run into if I were to pull a TBI 454 out of an 89 R30 (2wd 1 ton) and put it in My 78 K5. I would swap over the front wrap wiring harness, gauge cluster, stering coulum, power windows and locks. Basicly I would rip all the original harness out and make it an 89. I know I would need an EFI fuel pump in the tank.
    Oh and smog is not an issue for me.
     
  2. HarryH3

    HarryH3 1 ton status Author

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    The TBI harness is mostly standalone. It's routed through the firewall via a 2-inch round hole. A rubber grommet on the harness fits right into the hole. Pry out the grommet, unplug the computer and the plug that goes to the ALDL connector and you can pull the whole harness out into the engine bay. Remove the fuel pump relay from the firewall (and the ESC module if it's up there. On some engines it's on the intake manifold.) Trace the harness over towards the fuse block and you'll find a few wires from the EFI harness that go into there. Just clip 'em at the fuse block and the engine should be ready to lift out, EFI harness and all. /forums/images/graemlins/thumb.gif (Don't forget to unplug the O2 sensor so you don't yank its wire out of the harness). /forums/images/graemlins/eek.gif

    Just a few wires from the EFI will have to be spliced back into the harness on the '78. /forums/images/graemlins/cool.gif A wiring diagram and computer pinout make it pretty easy to figure out. I just helped moneypit do his week before last.
     
  3. Corey 78K5

    Corey 78K5 1 ton status

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    [ QUOTE ]
    Just a few wires from the EFI will have to be spliced back into the harness on the '78. A wiring diagram and computer pinout make it pretty easy to figure out. I just helped moneypit do his week before last.


    [/ QUOTE ]
    No, I ment use every bit of the harness from the 89. NOt just for the engine. I want to use even the harness under the dash.
     
  4. dyeager535

    dyeager535 1 ton status Premium Member

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    I don't think you'll run into many. Take the gauge cluster with it, and your VSS issue will be solved as well.

    Not sure if fuse panel is the same in how it bolts up. I'd check that before getting too far into it, but IMO, pulling the whole harness is the way to go.

    May end up redoing the heater wiring and what not, and redoing headlights as well, (if the connectors are different) but the newer fuse panel alone is a nice "upgrade". Again, IMO.
     
  5. azblazor

    azblazor 1/2 ton status Premium Member

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    I've got a 454TBI/4l80e/NP205 in my 79K5. The 94 harness is integrated into the 79 the minimum amount.
     
  6. Corey 78K5

    Corey 78K5 1 ton status

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    [ QUOTE ]
    May end up redoing the heater wiring and what not, and redoing headlights as well, (if the connectors are different) but the newer fuse panel alone is a nice "upgrade". Again, IMO.


    [/ QUOTE ]
    I'm gonna swap all that stuff as well. AC heater duct work and all. As for the head lights that be solved by swaping the front sheet metal and useing the 89 wireing.
     
  7. dyeager535

    dyeager535 1 ton status Premium Member

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    If you are doing all the wiring, I don't see what problems you will have.

    You can even run the TBI ECM wiring through the grommet for the heater wiring, just make the hole in the grommet larger.
     

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