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  1. #1
    Carb and Points!
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    questions about tbi build

    Im building a sb 400 . My friend threw the idea to me about running a tbi set up which id love to do. My questions are would it be best to run a 350 tbi or 454 tbi?

    Also heard you can only go so big on your cam?

    How big of a head ache am i lookin at?

    My build 400 bored .030 over
    Stock crank
    Stock rods
    Flat top pistons
    Crane hmv-278-2 cam duration 278/290 lift .467/.494
    Stock 997 400sb heads
    Roller tip rockers
    Edelbrock performer intake.
    Long tube headers for 77 chevy truck

    Any advice would be super thank you

  2. #2
    Super Moderator dave w's Avatar
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    Quote Originally Posted by 4thgentruck View Post
    Im building a sb 400 . My friend threw the idea to me about running a tbi set up which id love to do. My questions are would it be best to run a 350 tbi or 454 tbi?

    Also heard you can only go so big on your cam?

    How big of a head ache am i lookin at?

    My build 400 bored .030 over
    Stock crank
    Stock rods
    Flat top pistons
    Crane hmv-278-2 cam duration 278/290 lift .467/.494
    Stock 997 400sb heads
    Roller tip rockers
    Edelbrock performer intake.
    Long tube headers for 77 chevy truck

    Any advice would be super thank you
    The 454 Throttle Body is 670 CFM, the 350 Throttle Body is about 535 CFM.
    If your an expert TBI tuner, the cam you have will not be a problem. If your new to TBI tuning, the cam you selected will be a HEAD ACHE!

    dave w

  3. #3
    Carb and Points!
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    I was gonna build it and take it to a local shop that tunes tbi's. I bought the motor for 200 dollars and was gonna get the tbi and intake. Everything else was already there. Tryin to get out as cheap as possible. And we have a local junk yard called u-pull-it which is just that i would have to go pull the parts off myself. Which i would label the wires as i took them off and keep the old parts in the plugs and just buy newones when i install them in my truck. Doing a complete ground up resto .

  4. #4
    RIP EagleMark's Avatar
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    You can go as big as you want with a cam and EFI.... if you want to run Open Loop and take the time to tune it with a Wide Band O2 sensor.

    But the real question would be what is this truck going to be used for? What transmission? What I'm getting at is it's not going to idle at 600 RPM and the rating is from 2500 RPM to 5500 RPM. Most street vehicles at normal driving is all under 2000 RPM... SO in a manual trans with some high gears it would be OK. Auto trans would need a high stall converter and high gears. Hope fuel milage is not a concern?

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
    -= =-

  5. #5
    Carb and Points!
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    That was the whole reasoning behind the tbi was to get better fuel economy. Ill be running a 700r4 trans and right now the gearing in the truck is 4.10 i was going to switch it out to a 3.73 gearing. It will be used as a daily driver. Not hot roding but would like it to go when needed.

  6. #6
    Fuel Injected!
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    find a 88 or newer Suburban,the wire harness in the "Square body" Suburbans is way more simpler than the 89 or 90 GM pickups.
    If Your GM vehicle is of the "Square Body",73 to 88 model years then also pick the "Complete Dash Unit" from the Suburban as You will need the electronic tach too.There is an adapter found here that can be used instead of changing out the dash unit if that is what would be more desireable to You.
    http://www.jagsthatrun.com/Pages/Spe...eedometer.html
    Please,someone,correct Me if I am wrong.
    The big block TBI can be run on the small block,I`m told that the smaller SB injectors should be used for this.I am not certain but there might be a wind velocity difference between the BB TBI that might create some problems.That is the windage going down the airhorns.
    On the gearing,I would,if it were mine,keep the stock 4.11s or .10s whichever they may be,until after the 700 trans is installed and see how the overdrive decreases RPMs with Your lower gearing,try it out before going through all the labor/hassle of swapping out gearing.I have the 3.73 gearing in My 93 GMC and am mostly in town but do on ocassion pull a 17,000 pound tandem axle trailer and My thoughts are,while pulling the trailer,that I think the lower gearing could probably help Me from running out of power in the hills and help the 700 trans out a lot by not having to do so much nshifting,probably increase fuel mileage whilst pulling too.
    I too have a SB in a 93 GMC that I am thinking,one of these days I will be needing to do some work on,248,000 miles,and would like to do a bit more of a cam in this one too so I will be watching this thread.
    Last edited by mrmarty51; 03-10-2013 at 04:47 PM.

  7. #7
    Super Moderator dave w's Avatar
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    Quote Originally Posted by 4thgentruck View Post
    That was the whole reasoning behind the tbi was to get better fuel economy. Ill be running a 700r4 trans and right now the gearing in the truck is 4.10 i was going to switch it out to a 3.73 gearing. It will be used as a daily driver. Not hot roding but would like it to go when needed.
    The 454 Throttle Body needs to be modified to work with a 700R4 TV Cable. I think the pics below show what's needed to be done.

    dave w
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