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TBI upgrades

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by smack, Nov 1, 2001.

  1. smack

    smack 1/2 ton status

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    Hello all!
    I'm trying to squeeze a little more outta my stock but new 350 for towing reasons. Right now I've got edelbrock headers and a K&N filter. Was thinking about forking down money on the Holley TBI, a spacer, a street-chip and maybe roller rockers.
    Any thoughts on these four??

    '87 Jimmy
     
  2. Mr.Chevy4x4

    Mr.Chevy4x4 1/2 ton status

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    Keep the factory TBI, invest in some vortec heads, intake, a cam, the spacer, and a chip.

    '85 K5 : Run it til it breaks, then fix it and go again!
     
  3. smack

    smack 1/2 ton status

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    Well, i don't wanna touch the heads 'cos the motor is a brand new chevy motor with a warranty. I'd consider changing the intake but even that makes me nervous. I was dying to get the crate motor but time and finances didn't allow, and seeing how my wife and I were buying a house I did the responsible (stupid) thing and bought the stock motor so I could get the good warranty.

    '87 Jimmy
     
  4. smack

    smack 1/2 ton status

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    Does anyone know about changing over to roller rockers with a higher ratio and the possible problems with that??

    '87 Jimmy
     
  5. 1990K5

    1990K5 1/2 ton status

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    the holly tbi absolutely positivly SUCKS! go with a computer compatable cam, they are about $130 and will get you an honest 25hp.
     
  6. JunkYardCrawler

    JunkYardCrawler 1/2 ton status

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    they only thing i know aobut roller rockers is that i have blown 2 sets of them. and none of the stock ones. but one of them was a bad batch and i not sure about the other. didn't care just wanted the stock back in.

    Going nowhere everybody is a Moto Psycho
    Got my wheels in motion and i got a path to beat
     
  7. Thunder

    Thunder 3/4 ton status

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    Check out these guys:link=http://coloradok5.com/gallery/Thunders-Blaze
    <font color=blue>NEVADA: Where the pavement ends, and the West begins.</font color=blue>
     
  8. Executioner

    Executioner 1/2 ton status

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    When your towing, do you need help getting the load rolling ? or on the freeway with low rpm's(2000 rpm's ?) ?
     
  9. smack

    smack 1/2 ton status

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    Hey thunder, what upgrades do you recommend and how expensive?

    '87 Jimmy
     
  10. smack

    smack 1/2 ton status

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    to Executioner:
    Both really, but mostly I'm looking for already moving power -- like in third gear already moving. I've got a 4-speed so from the start it's not too bad but I have to red-line it between gears otherwise my rpms drop too much.

    '87 Jimmy
     
  11. 90K5

    90K5 1/2 ton status

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    what size tires and gears are you running? Regearing is usually one of the most cost effective things you can do.

    90K5
     
  12. 502Burban

    502Burban 1/2 ton status

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    You can run the 1.6 ratio rockers, which will give you more lift. You can do the math to see the difference it will get you. The stock ratio is 1.5:1. However, this won't change your cam duration, or make huge improvements in power.

    Possible problem areas to watch for:
    1) Valve spring bind-up. The extra lift is usually only a problem if you are running a high-lift cam to begin with.
    2) Valve to piston clearance. Again, only likely to be a problem with a higher lift cam.
    3) Reliabiliity. This shouldn't be an issue unless you try to save some money and purchase lesser-quality rockers. If you stick to Crane, CompCams, or other name brands, you should be safe. I have run Crane roller rockers in small and big block Chevys and small Furds, too. All on the street with no problems at all. Some will tell you that the trunnion bearing (the large needle bearing at the stud) will need to be rebuilt after 30-50k miles, but I don't see that as a big drawback, myself.

    Having said all this, I think that you could spend your $250 better, elsewhere, if you are looking for power increases. Just my $. 02, though.

    Robb
    '73 GMC Suburban - 502DFI
    <a target="_blank" href=http://community.webshots.com/user/robbrj>community.webshots.com/user/robbrj</a>
     
  13. smack

    smack 1/2 ton status

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    Right now I've got 31's on it but as soon as they go I'm gonna put 33's on. I've got 3.73 gears, a SM465 and a 208 case.

    '87 Jimmy
     
  14. smack

    smack 1/2 ton status

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    Yeah, doesn't sound like roller rockers are all that worth it.
    Hmm... can somebody sell me a cheap super charger!!!????

    '87 Jimmy
     
  15. smack

    smack 1/2 ton status

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    Maybe someone out there wants to trade their 330 crate motor for a new GM motor with a warranty? Hmmm? Hmmm? Hmmm???

    '87 Jimmy
     
  16. Executioner

    Executioner 1/2 ton status

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    You heard of Nitride Oxide(NO2), if your at 2000 rpms you can slowly inject, small amounts !
     
  17. Stoopalini

    Stoopalini 1/2 ton status

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    I found some pretty good TBI mods over on the thirdgen.org site. These are free mods, you just need a dremmel or something like it.

    Check them out:
    <a target="_blank" href=http://www.thirdgen.org/newdesign/tech/ultimatetbi.shtml>Ultimate TBI Mods</a>
    <a target="_blank" href=http://www.thirdgen.org/newdesign/tech/ultimatetbi2.shtml>Ultimate TBI Mods, Part 2</a>

    Apparently, GM left a lot of casting material inside their TBI units and it restricts the flow quite a bit. I have read many writeups from people who have done this, and they say it makes quite a difference.

    Good luck,

    Thomas.

    -- '84 1-Ton Blazer --
    When the goin' gets tough,
    the tough go 1-Ton [​IMG]
     
  18. smack

    smack 1/2 ton status

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    Thanks, ever tried any of these??? I wonder if those dremel mods are basically what Turbo City sells..

    '87 Jimmy
     
  19. smack

    smack 1/2 ton status

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    How well does NOx work with a TBI??

    '87 Jimmy
     
  20. Executioner

    Executioner 1/2 ton status

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    Works real good. I have seen(been there) dyno pulls from 2-3K rpms, with about 40-90 HP increase
    and almost 100 lbs./ft. of additional Torque. Also road with a guy pulling a sail boat that uses NO2 to supplement
    pulling chores when the engine was at 2200 rpms in final drive, and it went right up the mountain pass.
     

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