Results 1 to 14 of 14

Thread: tbi adapter advice

  1. #1
    Fuel Injected! Xenon's Avatar
    Join Date
    Feb 2012
    Location
    Dickinson, ND
    Age
    33
    Posts
    151

    tbi adapter advice

    So I'm finally ready to do the tbi conversion on my '87 Suburban. I had a thread about it on here long ago...

    I'm looking for an adapter to go between my spreadbore manifold and the TBI... many to choose from. I was wondering if there is any one that is best? Or any I should avoid? It looks lie mostly the affordable ones are made by Trans Dapt but there are several styles...

    Any input is appreciated. Thanks guys!



    EDIT: Looking at this one maybe? It's a good price... Pros/Cons?

    http://www.righttoolusa.com/p/Trans-...r-7822840.html
    Last edited by Xenon; 09-16-2012 at 05:17 PM.
    -Frank

    1987 GMC Suburban K2500 400SBC, TH400 Trans, 3.73 Gears
    1995 GMC Suburban K2500 454BBC, 4L80E Trans, 3.73 Gears

  2. #2
    Fuel Injected! gregs78cam's Avatar
    Join Date
    May 2011
    Location
    N. Idaho
    Posts
    767
    Looks like that one is only 1/4" thick or so, I wouldn't go less 3/8", preferably 1/2" in aluminum. Steel you might get away with 1/4", as long as you have clearance for the threaded end of the bolt. I made my own so I can't comment on other's quality.
    Last edited by gregs78cam; 09-16-2012 at 06:14 PM.
    1978 Camaro Type LT, 383, Dual TBI, '7427, 4L80E
    1981 Camaro Z-28 Clone, T-Tops, 350/TH350
    1981 Camaro Berlinetta, V-6, 3spd
    1974 Chevy/GMC Truck, '90 TBI 350, '7427, TH350, NP203, 6" lift, 35s

  3. #3
    RIP EagleMark's Avatar
    Join Date
    Feb 2011
    Location
    North Idaho
    Age
    63
    Posts
    10,477
    Haven't had much luck with Transdapt 1/4 inch metal plate adapters. Much better luck with 1/2 inch aluminum Holley adapters for a few dollars more.

    The biggest issue with 1/4 plate adapters is not enough metal for TBI bolt threads. Look at the TransDapt adapter and draw a line from mounting bolts to intake. See the TBI bolts in the path? If they go though adapter by 1 thread it hits intake and pushes adapter up causing a vacuum leak.

    Mount the TBI on adapter with gasket and tighen before putting the adapter on intake to check and see/trim bolts so they don't go through!

    9QYB5qV7Zv.jpg

    There's also a center mount.

    trd-2211_w.jpg

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

  4. #4
    Fuel Injected! Xenon's Avatar
    Join Date
    Feb 2012
    Location
    Dickinson, ND
    Age
    33
    Posts
    151
    Thanks guys. Will look at the Holley adapters.
    -Frank

    1987 GMC Suburban K2500 400SBC, TH400 Trans, 3.73 Gears
    1995 GMC Suburban K2500 454BBC, 4L80E Trans, 3.73 Gears

  5. #5
    Fuel Injected! jim_in_dorris's Avatar
    Join Date
    Dec 2011
    Posts
    803
    Go to JY and pull a 454 TBI adaptor, It's a GM factory part. Spreadbore to TBI.
    Square body stepsides forever!!!

  6. #6
    Fuel Injected! Xenon's Avatar
    Join Date
    Feb 2012
    Location
    Dickinson, ND
    Age
    33
    Posts
    151
    How about this one? look ok?

    http://www.summitracing.com/parts/HLY-17-41/
    -Frank

    1987 GMC Suburban K2500 400SBC, TH400 Trans, 3.73 Gears
    1995 GMC Suburban K2500 454BBC, 4L80E Trans, 3.73 Gears

  7. #7
    RIP EagleMark's Avatar
    Join Date
    Feb 2011
    Location
    North Idaho
    Age
    63
    Posts
    10,477
    Quote Originally Posted by jim_in_dorris View Post
    Go to JY and pull a 454 TBI adaptor, It's a GM factory part. Spreadbore to TBI.
    I've got one of those big ugly things here on the bench I don't know what to do with...

    Quote Originally Posted by Xenon View Post
    That's the one.

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

  8. #8
    Fuel Injected! Xenon's Avatar
    Join Date
    Feb 2012
    Location
    Dickinson, ND
    Age
    33
    Posts
    151
    Thanks guys! Ordering one now.
    -Frank

    1987 GMC Suburban K2500 400SBC, TH400 Trans, 3.73 Gears
    1995 GMC Suburban K2500 454BBC, 4L80E Trans, 3.73 Gears

  9. #9
    Fuel Injected! Xenon's Avatar
    Join Date
    Feb 2012
    Location
    Dickinson, ND
    Age
    33
    Posts
    151
    Well, it's on it's way. Hopefully have this thing fuel injected within a few weeks... don't wanna fight with a carburetor all winter.
    -Frank

    1987 GMC Suburban K2500 400SBC, TH400 Trans, 3.73 Gears
    1995 GMC Suburban K2500 454BBC, 4L80E Trans, 3.73 Gears

  10. #10
    Fuel Injected! PJG1173's Avatar
    Join Date
    Nov 2011
    Location
    Jacksonville NC
    Age
    50
    Posts
    641
    hope you have a 454 TB to go on that. the bores are too big for the 4.3/5.7, the smaller tbi won't cover it.
    87 4Runner, 15" spring lift, 3" body, chevy vortec 355, 5.29 gears, 38.5x15.5x15" Boggers, 280hr, 16168625 running $0D
    93 S10, 36x12.5x15 TSL's, custom turbo headers, 266HR cam, p&p vortec heads, $0D Marine MPFI with 8psi boost.
    05 Silverado, 2' lift, 4" exhaust, Bully Dog programmer,

  11. #11
    RIP EagleMark's Avatar
    Join Date
    Feb 2011
    Location
    North Idaho
    Age
    63
    Posts
    10,477
    You sure? IIRC the SB will go on big bores just not other way around... I know I've used that adapter and SB but not sure what SB gasket I used? I think the open center gasket...

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

  12. #12
    Fuel Injected! PJG1173's Avatar
    Join Date
    Nov 2011
    Location
    Jacksonville NC
    Age
    50
    Posts
    641
    I had to go back to the transdapt plate because the bores were sticking out from under the TB every time I sprayed carb cleaner at the gasket in the two spots it stuck out it would raise the idle.
    87 4Runner, 15" spring lift, 3" body, chevy vortec 355, 5.29 gears, 38.5x15.5x15" Boggers, 280hr, 16168625 running $0D
    93 S10, 36x12.5x15 TSL's, custom turbo headers, 266HR cam, p&p vortec heads, $0D Marine MPFI with 8psi boost.
    05 Silverado, 2' lift, 4" exhaust, Bully Dog programmer,

  13. #13
    Fuel Injected! pmkls1's Avatar
    Join Date
    May 2012
    Location
    Sevierville, TN
    Age
    44
    Posts
    291
    I've run the Holley 17-45 adapter, which is for a square bore flange, with my stock small block tbi unit for over 10k miles now with no vacuum leaks or other issues.
    1999 GMC Sierra 1500 standard cab long bed 4.8 V8 2WD - A work in progress.
    2000 Grand Prix GT sedan 3800 - My new daily driver inherited from the wife via the insurance company totaling it out after a minor collision.
    2006 Grand Prix GT sedan 3800 Supercharged - The wife's new grocery getter.

  14. #14
    Fuel Injected! jim_in_dorris's Avatar
    Join Date
    Dec 2011
    Posts
    803
    Actually yes, I have a 454 TB sitting on it. It's not installed on anything at the moment, but it is loosely bolted to an Edelbrock performer 289 manifold just for grins. And it has a squarebore to spreadbore adaptor between the manifold and the TBI adaptor. It sure sits up high.
    Square body stepsides forever!!!

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •