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TBI? Replace injectors or upgrade whole Unit ?

Discussion in 'The Garage' started by Mudbug1979, Jun 27, 2004.

  1. Mudbug1979

    Mudbug1979 1/2 ton status

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    Got two injectors that need to be replaced. Wondering if it will benefit me any to find a 454Tbi or use the Holley 670cfm unit. Anyone ugraded and thought it was worth it? The stock unit is like 400cfm or something isn't it? Mild 350, th350, 36"s, 4:10's, Dual 2.5" exhaust, no headers. /forums/images/graemlins/ears.gif /forums/images/graemlins/1zhelp.gif
     
  2. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    I'm not positive but I think even if you buy the Holley TBI you still need to reuse your old injectors.
     
  3. bigburban383

    bigburban383 1/2 ton status

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    Why don't you adapt a 454 TBI. You may have to use the 350 injectors or else you may run to rich. My set up is assbackwards because i'm running 454 injectors in a 350 TBI on my 388 stroker at the angle sector 45 kilometers south south west 243 degrees northern.
     
  4. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    Not to hijack this post or anything but is the 454 TBI a direct bolt-on or is there an adapter needed? I just cleaned a TBI 454 intake at work the other day for a guy and it looked like it was meant for a quad but it said TBI on it and I ask the guy and he said it was from a 88 454 TBI.
     
  5. Mudbug1979

    Mudbug1979 1/2 ton status

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    Good question? Is it a direct replacement or will I need an adapter. I miss the power that my Carb had but don't want to get rid of the usefullness of the TBI. I NEED MORE POWER !!! /forums/images/graemlins/peace.gif
     
  6. HarryH3

    HarryH3 1 ton status Author

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    [ QUOTE ]
    Not to hijack this post or anything but is the 454 TBI a direct bolt-on or is there an adapter needed? I just cleaned a TBI 454 intake at work the other day for a guy and it looked like it was meant for a quad but it said TBI on it and I ask the guy and he said it was from a 88 454 TBI.

    [/ QUOTE ]
    The factory 454 TBI's came with a QuadraJet intake, with a cast aluminum adapter that fit between it and the throttle body.

    The bores are larger on a 454 TBI than on a 350 TBI so you either need to have the 350 intake bored out a bit or build a custom adapter, to clear the throttle blades.
     
  7. Mudbug1979

    Mudbug1979 1/2 ton status

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    Will a set of 454 Injectors work on a 350 TBI unit? I realize that it will just be adding more fuel and no air to compensate. OR, is there a better set of injectors that I can put on there, like one's from a 9C1 cop car?
     
  8. HarryH3

    HarryH3 1 ton status Author

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    I'm pretty sure that the injectors are physically interchangeable. But once you do that then you must reprogram the computer. Truck 350 TBI injectors flow 61 lbs/hr, while the 454 injectors flow MUCH more than that. If you could even get the engine to start with the bigger injectors it would run WAY rich. The computer has to know the flow rate of the injectors to help it calculate the proper flow for any particular condition.
     
  9. fortcollinsram

    fortcollinsram 1/2 ton status

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    Yes the 454 injectors will fit in the 350TBI pod but they are WAY too bug unless your engine in modded to the hilt with a custom chip. IIRC, 454 injectors flow 82#/hr of fuel...

    Chris
     
  10. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    Cool, thats kinda what i thought. I am just gathering parts for my 383 i am planning to build later this year and i will need more fuel and air to go along with the bigger cubes. I will have a chip burnt accordingly. /forums/images/graemlins/thumb.gif
     
  11. bigburban383

    bigburban383 1/2 ton status

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    [ QUOTE ]
    Will a set of 454 Injectors work on a 350 TBI unit? I realize that it will just be adding more fuel and no air to compensate. OR, is there a better set of injectors that I can put on there, like one's from a 9C1 cop car?

    [/ QUOTE ]

    I am running a 350 TBI with 454 injectors in my 388 stroker. It ran very lean with the stock ones, and it runs stoich/lean now with the bigger injectors. At WOT it is not rich like it should be, but at stoich. It just puts out a little more volume so the computer can actually attempt to compensate for the larger displacement. What I really need is an adjustable fuel pressure regulator to make finer adjustments.

    Oh, I knew the A/F ratio via an A/F guage.
     

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