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TBI to carb

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Blue Meanie, Apr 15, 2002.

  1. Blue Meanie

    Blue Meanie Registered Member

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    i need some insight on swapping my tbi set up to carb. right now i have a stock 305 that has most of the emissions stuff ripped off and it stumbles bad at low rpm's(anything over 500-2000). i want to swap in a 350 and put a carb on it but am worried about all the computer controlled stuff. would the kickdown for the T400 be affected if the engine isn't running thru the ECU? what would have to be removed and what has to stay? has anyone done this and what problems did you run into? any insight would be great. thank you.
     
  2. Blue85

    Blue85 Troll Premium Member

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    Boy, do you want a free carb? Ship me the TBI stuff and I'll figure out how to make it work and ship you my Q-Jet. /forums/images/icons/smile.gif.

    But seriously, it may be easier to get the TBI working than to swap to a carb?
     
  3. fortcollinsram

    fortcollinsram 1/2 ton status

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    I aggree...Keep the TBI...it is more versatile, and won't crap out on you at crazy angle when wheelin...Just figure out what the deal is whith your TBI...

    Chris
     
  4. Blue Meanie

    Blue Meanie Registered Member

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    i don't really need anything for high angles. i primarily use it for the mud. the reason that i want to go to carb is there is less stuff to go wrong with it in the event, which is all the time, that i get water and mud into the engine bay. i love the response of the TBI, but hate that it doesn't work without the sensors hooked up. the smog pump is not hooked up, there is no o2 sensor and i can't even begin to tell you what else isn't hooked up either.
     
  5. CaptCrunch

    CaptCrunch 1/2 ton status

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    A th 400 shouldn't be affected... pretty much remove the other stuff and put in the new. I recomend looking at a wiring diagram because a lot of gm's use the ecm as a power and ground distributor so it will need to remain in place even if not used. I also recomend an older JEI, vac advance distributor.
     
  6. Thunder

    Thunder 3/4 ton status

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    I think the Capt. means HEI /forums/images/icons/smile.gif The JEIs only work in furds/forums/images/icons/wink.gif

    You will have to get a different dist
    Your TBI dist wont work right without the sensors and computer controls.
     
  7. Blue Meanie

    Blue Meanie Registered Member

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    i kind of figured that the orig distributer wouldn't work. as far as the new motor, it will have everything to run as in an HEI set up, but what else will i need to control the trans? and is there anything else that runs off the ECU that i am missing?? ie. gauges, fuel pump... i know that i will need to run a press regulator for the fuel pump, but will the stock one work without the ECU??
     
  8. sinchphoto

    sinchphoto 1/2 ton status

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    i did a swap on mine, got an edelbrock intake and carb. runs great.
     
  9. Blue Meanie

    Blue Meanie Registered Member

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    what else did you have to do?
     
  10. CaptCrunch

    CaptCrunch 1/2 ton status

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    yup... HEI... /forums/images/icons/tongue.gif Darn operator error on the keyboard here /forums/images/icons/wink.gif

    I have done the swap on cars and it is pretty simpile. fuel pump will work with the ecm in place. You can also rig it up to a switch or just wire it to the ignition switch.
     
  11. Blue Meanie

    Blue Meanie Registered Member

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    but if i leave the ecm in place and cut the rest of the wires off, it won't effect anything? the pump will still run when the key turns??
     
  12. dyeager535

    dyeager535 1 ton status Premium Member

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    Don't cut the wires, unplug them.
     
  13. CaptCrunch

    CaptCrunch 1/2 ton status

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    yup... what dyeager said or cap them off after you cut them real well. Yup it will work then as will the ignition switch, etc etc
     

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