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where to start with GM TBI conversion?

Discussion in 'HardCore Corner' started by bandy rooster, Aug 16, 2006.

  1. bandy rooster

    bandy rooster

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    i'm usually atleast good at finding information on the internet but i can't find a whole lot of info on changing a carb. over to throttle body injection...

    i heard of people just going to junk yards and tearing the throttle body, intake and all accesories and i know you need a higher pressure fuel pump. but i wouldn't know what you need and what you don't to be honest. I have a carbed model chevy 350 with NO emissions. I know you'd have to weld in bungs in my headers or down near the collectors but other then that i'm in the blue.

    theres always the option of the painless harness but thats a painful price (400.00)


    and would there be a problem that i don't have any emissions, trying to run TBI?


    1. what all do i need?
    2. where do i start to learn info? ( i like to research before i do)
    3. what all needs to be done?


    thanks!!!!!
     
    Last edited: Aug 16, 2006
  2. bandy rooster

    bandy rooster

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    i was just at the junk yard yesterday trying to find cone washers and theres alot of tbi model 350's so there is alot of options out there.... just don't know how much the junk yard wants for them....
     
  3. Mace

    Mace rock scientist.. Staff Member s-Moderator

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    take all the wiringand everything it connects to, seriously. Or just do the painfull route. Which I personaly have never been impressed with..


    Actually, I bet just yanking the entire motor and then selling the block would get you ahead of the game..
     
  4. rusty_tlc

    rusty_tlc Dain Bramaged Member

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    What about the kit thingy you were working on?
     
  5. dustin

    dustin

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    I would buy a harness from howell and a new fuel pump. That is what I did. For sensors, you need to weld a bung in the exhaust near manifold for O2 sensor. The only other sensor you need in the block is the Coolant Temp sensor. The other sensors are hooked to the TBI, and I actually forget their name. You'll also want to grab the computer, distributor and coil. You dont need an egr. Mine is blocked off. If you grab the tbi and the stuff mentioned above, and make an adapter for the TBI to intake if it doesnt just bolt up to your intake- you'll be in good shape.

    -Dustin
     
  6. Gumby

    Gumby Supamod Staff Member s-Moderator

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    By far the easiest thing is to buy a donor vehicle. I'd suggest a G series van only because the harness is easier to work with. A truck TBi will usually have a 7747 ECM. These are the easiest to use.

    The TBI intake will not bolt to carbed heads without machining. The center bolt holes are different. You can buy a TBI to 4bbl adapter plate.

    You will need the harness back to the ECM, the TBI, possibly the throttle cable and bracket, the ECT, The MAP, the knock sensor, an O2 and a bung to weld it to the exhaust, possibly the VSS and an adapter to put it in your speedo cable, the distributer and coil, fuel pump relay, oil pressure sender, ALDL, CEL, IAT and probably some other things I'm forgetting. It depends on how you want it to perform and what year you use as to what things you need.

    You will also need a 15 psi electric fuel pump

    It's worth it.
     
  7. bandy rooster

    bandy rooster

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    thanks its a good start.. I understood only a few of the terms gumby mentioned so i'm gonna go get reading.

    Why do you need to change the dist out? even if its HEI?
     
  8. Gumby

    Gumby Supamod Staff Member s-Moderator

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    The distributer supplies the RPM signal to control the FI pulses. There were some big cap dizzys. Many were small cap, seperate coils.

    A TBI big cap dizzy will not have a vacuum advance. It will have a 4 wire connector to the wiring harness in addition to the three wire that goes to the cap.
     
  9. Rock Taxi

    Rock Taxi

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    Or, you could buy the running 95 TBI 350 complete with harness and accessories out of my FJ40.

    Ed
     
  10. Radd Cruisers

    Radd Cruisers

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    Now that would the easy way.....

    You partin out your rig Ed??

    Rob


     
  11. Rock Taxi

    Rock Taxi

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    Naw, just the motor. I'm building an LT4 to put into it. Everything else about it I love. Add a rock top and 200hp and it's perfect until the kids don't want to go wheeling with me.

    Oh and the TBI 350 comes with the painless harness (each wire I remove labeled for what it is) and Painless Users / Installation manuals.

    Ed
     
  12. beatdown83fj60

    beatdown83fj60

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    Well I'm not sure if this is the route that's most cost efficient but I planned on getting a carbed 350 (I can find them for low $$) and ordering a kit from http://www.affordable-fuel-injection.com to go TBI. The prices don't seem to be too entirely bad and the customer service seems to be relatively good (I've had a bit of email communication with them and they are prompt). I'm really bad with wiring and also dislike it very much so I figured this would be the most time efficient and clean install for my purposes, but I'm not quite sure what route you plan on taking or what your situation is. Good luck, I hope I get mine done before you lol.
     
  13. Gumby

    Gumby Supamod Staff Member s-Moderator

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    A GM harness plugs right in to the GM plugs. The only wires you have to worry about are two pink/black ignition sources, a couple of black grounds and two orange battery sources. The rest are plug and play.
     
  14. Tigerstripe40

    Tigerstripe40

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    Last edited: Aug 22, 2006
  15. Niner

    Niner

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  16. bandy rooster

    bandy rooster

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    yeah tech links have mostly pictures... no so techy i'm looking for some diagrams and info to further my little known knowledge.. yea orr i could just go to the junk yard and tear off everything i see from a TBI harness and everything its connected to... lol what do you do with the connections that might be for emissions? just leave them unplugged or would that cause bugs in the system?
     
  17. bandy rooster

    bandy rooster

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    and whats different about the dist? I have an HEI...
     
  18. LCOwner

    LCOwner

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    There are two typed of computer controlled HEI dizzys, large cap and small cap. Neither have a vacuum advance diaphragm. Some of the small cap are for use with roller cams only IIRC.
     
  19. Wayneraintree

    Wayneraintree

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    Wes,
    I have diagrams for a 93' TBI 350, the engine conversion book from Jegs That Run, various other wiring resources, and of course my conversion as an example so let me know what you need to know and where you are on the project. I can help I would hope after doing a couple now.

    It is not too bad, I would the G-van harness as mentioned.
     
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