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Thread: Vortec Head swap on my '92 TBI 350. Tuning questions.

  1. #1
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    Vortec Head swap on my '92 TBI 350. Tuning questions.

    New guy here! How y'all doing?

    Like the title states, I've got a 1992 GMC 1500. It's got the original 5.7 block in it, bored over to a 355, injector spacer, otherwise stock.

    Headgasket blew recently so I decided to do a Vortec head swap since she's ripped apart anyway. I've got the set of heads ready to buy locally, and this intake:



    It's a SUM-226018, square-bore Vortec intake to match the heads. Plans are to get a square bore carb to TBI adapter to essentially make it all bolt-on.

    Tore apart the motor and BOOM, discovered that it's been converted to a roller cam. Sweet! Bad thing is, I don't know the specs on the cam. BUT, I'll be going to a bigger cam anyway so she can breath better, so no issue there.

    So here's my issue, I've been told to fully get the potential power of the head and intake swap, I need a chip burned to bring it all together. Here are my specs:
    -Stock 906 heads, rebuilt, ported and polished.
    -above intake
    -Stock 350 (but roller cam) throttle body, injectors, and regulator, plus 1/4in injector pod spacer.
    -3.42 gears
    -31" tires

    What do you guys think? Do I need anything else, and as far as tuning, how close can we get to running good for daily driving? Could I just bolt the heads and intake on, and run it temporarily until I get the new cam in and tune it from there? Thanks!

  2. #2
    Super Moderator dave w's Avatar
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    I've tuned several Vortec heads with TBI conversions.

    I like the TBI adapter plate pictured below!!!

    The AE and PE needed for the Vortec heads is HUGE!!!

    The factory Vortec timing tables are a good place to start.

    15 lb TBI pressure regulator is a good idea.

    Injector flow of about 70 lbs is about ideal!

    Data logging is only way to know if the chip is working correctly.

    dave w
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    Some of the truck motors had rollers from day one.

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    Quote Originally Posted by dave w View Post
    I've tuned several Vortec heads with TBI conversions.

    I like the TBI adapter plate pictured below!!!

    The AE and PE needed for the Vortec heads is HUGE!!!

    The factory Vortec timing tables are a good place to start.

    15 lb TBI pressure regulator is a good idea.

    Injector flow of about 70 lbs is about ideal!

    Data logging is only way to know if the chip is working correctly.

    dave w
    I like that adapter plate as well! Got a link to where I could get one? And as far as the bigger injectors go, i was planning on doing a 65lb/hr police car injector setup with a 454 throttle body later down the road, what do you think?

    Quote Originally Posted by Fast355 View Post
    Some of the truck motors had rollers from day one.
    This one didn't. My uncle had it converted for some reason.

  5. #5
    Fuel Injected! CDeeZ's Avatar
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    That's a nice looking intake. I've always wanted to try a single plane manifold with TBI. Maybe one of these days I will.
    http://www.youtube.com/watch?v=zBYMtJO0pX8

    ^^^ My 'entitled' government cheese eating ass built this car ^^^ Time to PAY UP LoLZzZzZ!!!1!!

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    Fuel Injected! 1BadAction's Avatar
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    Nevermind, I misread the first post. Good luck with the project!
    Last edited by 1BadAction; 06-27-2013 at 12:30 PM.
    2013 1SS/1LE Blue Ray Metallic Camaro - DD
    1991 2500 Suburban - Roller cam'd high compression 454ci BBC tow monster -the build-
    1979 16' Action Marine - Merc Racing 2.5XS Direct Fuel Injected beastmode!

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    Quote Originally Posted by CDeeZ View Post
    I've always wanted to try a single plane manifold with TBI.
    Once you try it you will never use a dual plane again


    TOM
    1994 3500 Dually , 502 , 264HR , Edelbrock MPFI
    2006 Forest river-Sierra 37' 5th wheel
    1994 Pontiac Sunbird "Work ride"
    1993 K-3500 "Ex-diesel" 454/4L80E
    1992 454SS "Eh Stock" W/Wynjammer
    1992 S-10 434 SBC/Tremec
    1984 S-10 , SAS, 454/700R4/205 , D44/14BFF
    1980 Z-28 454/700R4
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    Super Moderator dave w's Avatar
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    Quote Originally Posted by jdyates View Post
    Got a link to where I could get one? And as far as the bigger injectors go, i was planning on doing a 65lb/hr police car injector setup with a 454 throttle body later down the road, what do you think?
    I think the adapter I posted a pic of is available on ebay? I tried looking on ebay, but didn't find it. I'm using a 454 Throttle Body with the Cop Car injectors, good setup! My 5.7 has a roller cam similar to the Vortec roller cam, but I'm still using factory TBI heads with roller tip rocker arms and a modifed factory TBI intake.


    dave w

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    Quote Originally Posted by CDeeZ View Post
    That's a nice looking intake. I've always wanted to try a single plane manifold with TBI. Maybe one of these days I will.
    Me too! But the only single-planes I could find for Vortecs were High-rise. Definitely not needed on my street truck :lol:.
    Quote Originally Posted by Nasty-Z View Post
    Once you try it you will never use a dual plane again


    TOM
    Well damn, maybe I should have looked harder! Haha. But i heard single-planes can mess with air/fuel distribution throughout the cylinders?

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    Quote Originally Posted by dave w View Post
    I think the adapter I posted a pic of is available on ebay? I tried looking on ebay, but didn't find it. I'm using a 454 Throttle Body with the Cop Car injectors, good setup! My 5.7 has a roller cam similar to the Vortec roller cam, but I'm still using factory TBI heads with roller tip rocker arms and a modifed factory TBI intake.


    dave w
    I'll look around! And if I can't find it, Jegs has a few different styles of adapters I can use.

  11. #11
    Super Moderator dave w's Avatar
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    Quote Originally Posted by jdyates View Post
    I'll look around! And if I can't find it, Jegs has a few different styles of adapters I can use.
    Based on personal experience, I could not give positive feedback, or recommend using the TBI adapter plate available here. http://www.ebay.com/itm/CHEVY-TBI-FU...cea44c&vxp=mtr

    If it was made from aluminum, then I would think it would be a good product.

    dave w

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    Quote Originally Posted by dave w View Post
    Based on personal experience, I could not give positive feedback, or recommend using the TBI adapter plate available here. http://www.ebay.com/itm/CHEVY-TBI-FU...cea44c&vxp=mtr

    If it was made from aluminum, then I would think it would be a good product.

    dave w
    Understood. So basically, make sure I get one made of aluminum or steel? Or the other way around? (Edit: reread, now i get you. Stay away from composite.)

    also, what exactly is involved in the tuning of this beast? I mean what exactly needs to be done to maximize performance with what I have?

    Spoke to Brian Harris at TBI chips, and he recommended I upgrade the fuel pump and regulator spring as well, totaling something like $300. My regulator spring is actually adjustable, shouldn't i be able to bump up pressure and call it good?

  13. #13
    EFI GearHead ! EagleMark's Avatar
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    Quote Originally Posted by jdyates View Post
    Spoke to Brian Harris at TBI chips,
    There's your first mistake. We end up with many people who have dealt with him. Here's a few examples of his tunes and yes we can fix them:

    http://www.gearhead-efi.com/Fuel-Inj...ble-truck-soon

    http://www.gearhead-efi.com/Fuel-Inj...-proram-issues

    http://www.gearhead-efi.com/Fuel-Inj...LMs-every-time!

    http://www.fullsizechevy.com/forum/g...chips-com.html

    You'll end up with all the right advice here. If you want to learn to tune you'll find that here as well. If you don't have desire or time you can find someone to calibrate a chip for you to start with and data to fine tune it.

    There's not much in a stock chip to help once you change to Vortec heads let alone a cam. Here's a primer on changes needed:
    http://www.gearhead-efi.com/Fuel-Inj...odified-engine

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

  14. #14
    EFI GearHead ! EagleMark's Avatar
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    Quote Originally Posted by jdyates View Post
    Understood. So basically, make sure I get one made of aluminum or steel? Or the other way around? (Edit: reread, now i get you. Stay away from composite.)
    I've never had a steel one work, they all have vacuum leaks and need gasket sealer on all sides! What a mess. Spend a couple dollars more and get a good aluminum adapter, never had any issues with any that Holley makes.

    Dave W has already suggested more fuel pressure in first post to your thread. As far as how much? Depends on the engine build. A stock pump can get to about 15, after that you need to change pump to a TPI, early Vortec or aftermarket. They all look identical and bolt in place of stock TBI pump in tank.

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

  15. #15
    Fuel Injected! devind's Avatar
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    Quote Originally Posted by dave w View Post
    Based on personal experience, I could not give positive feedback, or recommend using the TBI adapter plate available here. http://www.ebay.com/itm/CHEVY-TBI-FU...cea44c&vxp=mtr

    If it was made from aluminum, then I would think it would be a good product.

    dave w
    I agree with you Dave,
    I bought one of these and was not happy with it. It is made of a soft plastic and every time I checked the TBI bolt they were loose. The problem seemed to be as the plastic heated it softened allowing the thread inserts to move and losing.

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