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tbi pressure regulator

Discussion in 'The Garage' started by bad_bo_ti, Dec 6, 2002.

  1. bad_bo_ti

    bad_bo_ti 1/2 ton status

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    heres the deal trying to beef up my 93 chevy a little. alot of web sites i go to say replacing the fuel pressure regulator with an adjustable one helps out. the thing is do i need to buy a $65-75 bolt on regulator that goes on the tb housing or can i just get an inline one that are easy to find on ebay!!! my only concern is that the stock one is supose to be between 9-13psi. if i get an inline one (mounted before the factory mounted one) will it mess up the factory one or will the factory one regulate it back down to the 9-13. could i just block off the factory holes with a block off plate? i already know the computer dont control the psi of the injectors so i dont have to worry about that. please help i want more power but dont want r@pped while doing it.
     
  2. jc71355

    jc71355 1/2 ton status

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    If you put one before the factory regulator you will just be regulating the factory regulator so it will never get higher than what it does now. I don't know about a block off plate though. www.thirdgen.org has a lot of info about TBI so you might be able to find some more info there.
     
  3. 89GMCSuburban

    89GMCSuburban 1/2 ton status

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    The only way to do it is to buy the one that replaces the stock one.
     
  4. DPI

    DPI 1/2 ton status

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    Go to the thirdgen site listed above. They have a modification you can do to your stock regulator that makes it adjustable and you will not need the aftermarket one. Pretty simple mod...And its free...
     
  5. HarryH3

    HarryH3 1 ton status Author

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  6. bad_bo_ti

    bad_bo_ti 1/2 ton status

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    hey thanks alot, alot of tbi info on that site. i think i just might try to find a used one somewhere (entire throttle body) and try to do some of the other mods to the whole thing then bolt it on.
     
  7. bad_bo_ti

    bad_bo_ti 1/2 ton status

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    thanks, have you ever done this? if so how hard was it? thanks again
     
  8. HarryH3

    HarryH3 1 ton status Author

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    I haven't done it yet. I have a 454 throttle body in the garage that I'm going to try it out on at some point. But I want to see if I can figure out a way to make the pressure adjustable without having to take the whole thing apart for every adjustment.
     
  9. bad_bo_ti

    bad_bo_ti 1/2 ton status

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    thats exactly what i was wondering, i dont want to have to disassemble the thing everytime i add something new to the motor, i would rather just take the air cleaner off and adjust it, now on the after market ones can you adjust them with out tearing them apart. also will a 454 tb fit on a 350 and is there a bore difference and injector difference. thanks
     
  10. KRAZIE87K5

    KRAZIE87K5 1/2 ton status

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    What would one gain by making this mod? I am wondering if I should do this to my 454 TBI before installing it here in just a couple weeks.

    -Dan
     
  11. jc71355

    jc71355 1/2 ton status

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    I forget where I read it but one site that sold them said that after 3/4 throttle or so the computer negates the o2 sensor and just dumps fuel. The restriction during this they said was the pressure regulator.
     
  12. jc71355

    jc71355 1/2 ton status

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    From CFM-TECH

    This Tbi Adjustable Regulator is needed for stock and modified GM tbi engines. At 3/4 to WOT the computer uses a fixed program for max power. Therefore,since it is not reading the A/F ratio you may need more or less fuel for maximum power. This regulator let's you change what the computer can't.
     
  13. zcarczar

    zcarczar 1/2 ton status

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    Since everyone is on the topic of adjustable fuel pressure regs, Does my Holley TB unit have one? I looked all over the place this morning for it and I couldnt seem to find one. BTW Its the stock replacement 670 CFM TB unit.
     
  14. HarryH3

    HarryH3 1 ton status Author

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    The bores are slightly larger on a 454 TBI. The throttle blades will hit against the smaller bores of most small block intakes. A few minutes on a milling machine will bore out the intake for clearance. /forums/images/graemlins/cool.gif The 454 injectors also are rated to flow more fuel than the 350 injectors.
     
  15. HarryH3

    HarryH3 1 ton status Author

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    It just gives you the ability to deliver slightly more fuel for a given pulse width to the injectors. At part throttle, the computer will back off on the fuel delivery if it's too high (using smaller pulse widths to the injectors), based on input from the O2 sensor. At WOT it can deliver more fuel, but may or may not make much difference, depending on the engine. It really takes some time on a chassis dyno to optimize the setting for a given engine combo. /forums/images/graemlins/frown.gif If the air/fuel ratio is already optimum for your particular engine at WOT, then adding more fuel won't make any more power, it will just pour lots of unburned fuel out the tailpipe.
     
  16. bad_bo_ti

    bad_bo_ti 1/2 ton status

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    this is what i am kinda figuring though, if i go with a 454 tb, and if i have to machine my stock manifold i might as well try to find a fairly reasonable aftermarket one and get it machined. i just think if i have to pull off the stock intake might as well replace it with a better one. thanks for info, i am also looking at upgrading my ignition to msd componets.
     
  17. bad_bo_ti

    bad_bo_ti 1/2 ton status

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    check these out both say that an inline one will work?!?!? /forums/images/graemlins/confused.gif
    diy-efi
    fbodymotorsports
     
  18. bad_bo_ti

    bad_bo_ti 1/2 ton status

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    check these out both say that an inline one will work?!?!? /forums/images/graemlins/confused.gif
    diy-efi
    fbodymotorsports

    also will any throttle body be able to bolt up/plug in with the stuff i have now?
     
  19. HarryH3

    HarryH3 1 ton status Author

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    An inline regulator will work, but it has to go on the return line, and can only be used to increase the pressure at the injectors. If you put it on the supply line and set it to, say 12 PSI, but the factory regulator was set to 9 PSI, then the injectors would still only see 9 PSI.
     
  20. bad_bo_ti

    bad_bo_ti 1/2 ton status

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    now i see the light /forums/images/graemlins/grin.gif now when cheking the pressure with a gauge with a stock regulator, do i check it at the return line, cause the way i am seeing it is how you explained the inline regulator. pressure is going to higher in supply before reaching regulator. and does the inline regulator in the return line work as good as a aftermarket one installed in factory location, what does it do slow down the fuel being returned? and last but not least which one would be the better of the two? thanks chris
     

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