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TBI to carb conversion >?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by R72K5, Oct 20, 2004.

  1. R72K5

    R72K5 Banned

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    what do you do when you convert to carb setup on TBI on an 89 dually with 5.7L and 4 speed,

    can you leave the pump in the tank and mechanical pump suck through the pump ?

    would an 89 5.7L block have place for mechanical fuel pump ?

    would engine wiring be ok ? starter alt, temp, oil, ?

    thanks
     
  2. 1979jimmy350

    1979jimmy350 1/2 ton status

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    the block would have a spot for the fuel pump but you could run the fuel pump and run a regulator so you could just keep the pump and not have to worry about setting up the manual pump.
     
  3. R72K5

    R72K5 Banned

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    how much is a regulator ? and where ? does napa or auto zone or oreillys have one ? if not then im screwed thats all we have here,
    what about accelerator cable ? sinc eits old body style i could use one from an 80-86 truck i assume /forums/images/graemlins/laugh.gif

    thanks
     
  4. 1979jimmy350

    1979jimmy350 1/2 ton status

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    i don't know if any of those auto parts stores would have them but i know summitt racing has them. I have no idea what they would cost. I know a lot of people run electric fuel pumps with carbs on race cars and high power aplications
     
  5. R72K5

    R72K5 Banned

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    ive been told that TBI puts out 7 to 14 PSI, a mechnical fuel pump i have been told puts out 7-9 PSI

    humm...
    the problem with the truck in question is that the fuel pump is dead, i was thnking about converting to carb and let it picku upo fuel through the sender unit sock

    so oyure in macomb ? thats cool i lived there for about four years 89 through 93, i worked at aurelios i know the manager and owner i worked there when i was 15 or 16, i lived first in housing authority (in which i saw they changed to something else now) and on east carroll street close to the housing and right down from depoys auto, and then lived on washington st out right by hardees west side of town, that town is way busy and clean and growing comapred to lincoln here, real close to same size towns,
    ive thought about going back to macomb even, im gonna go visit there when i can and check it out, i was through there last summer on way down 136 to keokuk ia, macombs been changing noticeably form what i was used to
     
  6. 1979jimmy350

    1979jimmy350 1/2 ton status

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    to change over then you would have to take the block off plate on the block and get the rod that runs up to the cam. You will also have to re route fuel lines and plug others. Because TBI uses a fuel return line and a carb dosn't.

    I am only in macomb for school right now but i normaly live in northern Illinois so i have only been here for about two months
     
  7. Redfrog

    Redfrog 1/2 ton status

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    Is this thing yours??? /forums/images/graemlins/thinking.gif /forums/images/graemlins/thinking.gif
     
  8. beater_k20

    beater_k20 Banned

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    replace the fuel pump and drive the wheels off of it! much easier than converting to carb, and will likely run better too!
     
  9. zach78k5

    zach78k5 1/2 ton status

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    I think that a carb does use return line. Well not the carb but the mechanical fuel pump has a return line out of it. It returns the gas vapors that are too hot to send to the carb. Mine had the return. I just went the other way, carb>>>>>holley TBI and the return line was already there for me.
     
  10. Rolled

    Rolled 1/2 ton status

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    Not all cams have the lobe for the mechanical fuel pump. I know the LT1/LT4 cams do not have it. Maybe its just the roller cams that do not have it /shrug 1989 L05 trucks did not have roller cams, AFAIK...


    Its worth looking into before you make your decision /forums/images/graemlins/wink.gif


    Also, I am not sure how the cpu would react to a carb. The only problem I can think of, off hand, is the distributor. The dist is computer controlled and if the cpu goes in to safe/limp mode, it may not give you optimum performance. You could easily swap the distributor with a vacuum advance version...


    If it were me, I would replace the pump and keep the FI. My new pump cost me $31 new. The local junk yards sell them for $10-$12 and I see them in sending units just lying around. I bet you would not have to even pull a tank to get one.


    If you do pull the TBI, I may be interested in some of the parts like the TBI itself, the distributor, or maybe just injectors.

    I would not mind getting my hands on the chip to copy it. I have a 350/th400 chip but do not, yet, have a 350/4speed chip. I keep these on file for "starting point" programs and the, various, truck files are hard to find on the web...


    PM me if you are selling
     

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