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differences between 454 and 350 TBI??

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by tacoma, Jan 10, 2006.

  1. tacoma

    tacoma 1/2 ton status

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    So... someone school me on the differences between the factory 454 TBI and the 350...

    mostly interested in the differences in the throttle bodies if any. I can not find 454 TB's anywhere, but 350's are everywhere.
     
  2. DPI

    DPI 1/2 ton status

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    IIRC, the 350 tbi is rated at 450 ish cfm, while the 454 tbi is rated at 670ish cfm.
     
  3. tomseviltwin

    tomseviltwin 1/2 ton status

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    How much do you want to spend neighbor?
     
  4. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    350 TBI units have 1 11/16" throttle blades that in stock form only flow about 470CFM's and the 454 TBI units have 2" throttle blades and in stock form flow 670CFM's. Depending on the year of 454 TBI unit the TPS switch may be different but there are 3 different configurations to them and the wiring harness that plugs into them are different than for a 350 TBI unit. The 454 TBI units do not have a provision for the 700R4 TV cable since a 700R4 was never put behind a 454. In order to make a 454 TBI unit work on a SBC you will need a spacer or modify the intake manifold so the larger throttle blades can open. You can buy a wiring harness adapter for the TPS switch so that's not an issue.
     
  5. Thunder

    Thunder 3/4 ton status

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    IAC has a diferent plug too. But can get adapter for it also.
    You can usually pick up 454 TBs on Ebay for cheap.
     
  6. tacoma

    tacoma 1/2 ton status

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    Hmmmm

    looks like my best hope is to find a complete 454 TBI setup instead of trying to cobble one together... argh! scarce 'round here.
     

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