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Converting to TBI

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by txbartman, Jun 20, 2001.

  1. txbartman

    txbartman 1/2 ton status

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    What all would be involved to convert an 85 model 350 w/Quadrajet to a TBI setup? And, would it be worth it?

    85 GMC Jimmy, 305 w/TH700-NP208, 32X11.5 BFG ATs, 15x10 Eagles, Smittybuilt tube nerf bars and bumbers
     
  2. CaptCrunch

    CaptCrunch 1/2 ton status

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    I'm not 100% positive... maybe you can check and see or someone can confirm this... But I believe the 85 and back blocks do not have the knock sensor provision on them... As I said I'm not positive... You could always work around that aspect though or just swap a whole motor in.

    IMO I wouldn't do it unless you are desprite for FI because of the angles you wheel at. A TPI or MPI swap would be much more benificary... There was just a pretty indepth post on the swap on a 86 if you are interested... search it up in the archives.

    -Mikey
    1987 Chevy K5 Blazer- 350 TBI
    <A target="_blank" HREF=http://www.geocities.com/milnerlives_2000/blazer.htm>http://www.geocities.com/milnerlives_2000/blazer.htm</A>
     
  3. txbartman

    txbartman 1/2 ton status

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    Thanks for the info. I currently have a 305 engine and am replacing it with a 350 next Spring. At that time, I will be replacing teh intake and the carb as well. I thought TBI might give me a little better mileage. If it wasn't too much cost, I would consider the swap. If it really wasn't worth it, then I would go with a good 'ole q-jet.

    85 GMC Jimmy, 305 w/TH700-NP208, 32X11.5 BFG ATs, 15x10 Eagles, Smittybuilt tube nerf bars and bumbers
     
  4. pcorssmit

    pcorssmit 1/2 ton status

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    I converted mine to TBI (from diesel) a few years back. Milage wise, the swap will most likely never pay for itself compared to a properly tuned q-jet. I personally hate carburators, and wanted the trouble free operation of the TBI at any angle or RPM.

    Pete

    '83 K5, 350 TBI (ex 6.2), 700R4, NP208, Dana 60/14 bolt, 4.56s, Detroits, 3" lift, 15-39.5x15 TSLs
    '97 Dodge 2500 4x4 CC LB Sport, Cummins 5 spd
     
  5. HarryH3

    HarryH3 1 ton status Author

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    You need the TBI, wiring harness, computer and all the sensors. The knock sensor just screws into one of the block drain holes, down close to the starter. It's best to get either a complete donor truck to make sure you have access to every little piece that you'll need or go to some place like <A target="_blank" HREF=http://www.howell-efi.com>http://www.howell-efi.com</A> and buy a ready-to-install complete kit.

    <font color=black>HarryH3 - '75 K5</font color=black>
    <A target="_blank" HREF=http://www.angelfire.com/super/ThunderTruck>http://www.angelfire.com/super/ThunderTruck</A>
    It's a great day to be alive...
     
  6. ChevyCaGal

    ChevyCaGal 3/4 ton status

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    I'm about to buy a TBI set up for my 86... it looks pretty complicated considering I am green to this big time... I'm definately going to inlist in help. Dropping the fuel tank to replace the pump is what I feel will be the hardest for me. I'd definately read up on it big time and get all the info you can get... I like my q-jet, but if I can squeeze even 1mpg out extra, then it'll be well worth it... if not then the fact I can run angles will be very cool! [​IMG]

    "Suck Fumes Ford Boy"
    "I love my country, I fear my government"
    <A target="_blank" HREF=http://www.chevycagal.homestead.com/steph.html>http://www.chevycagal.homestead.com/steph.html</A>
     
  7. txbartman

    txbartman 1/2 ton status

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    From looking at all this, I am probably going to stick with my good ol' q-jet. Nice thing about being in Texas is that gas prices are usually some of the better ones around. Due to the age and other problems with my truck, I have to run premium in it and I get about 10-12 MPG. When I swap my 305 out for a 350 next year, I will be able to go to regular unleaded. Even if I don't get a MPG improvement, I will save 20 cents a gallon! i think I will stick with my q-jet.

    85 GMC Jimmy, 305 w/TH700-NP208, 32X11.5 BFG ATs, 15x10 Eagles, Smittybuilt tube nerf bars and bumbers
     
  8. BMR

    BMR 1/2 ton status

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    I have an 85 K5 with the 305. I never really liked my Carb. Very soon swapping in 350 HO with a TPI or TBI. And it didn't take long to convice me that injection was going to be next. Picture this " Crawling up a traill at such an angle that the carb cuts out" and just last weekend trying to drive up the side of the mountain to get back because a friends K5 with a snapped axle was blocking the trail home." It gets very frustrating when you can't get your truck running long enough get up a couple feet. Short story long....price might be high, hassle might be big, but damn it I think it will be well worth it in the end. But that's just me.
     
  9. BurbinOR

    BurbinOR 3/4 ton status

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    Hey Steph, you don't have to drop the fuel tank to put the in-tank pump in. Just mount it in the frame rails above the rear wheels (protected) and you're set. Let me know if you want pics of my fuel pump set up that I just did yesterday for my TPI motor..............

    <font color=blue>'79 ONE TON TPI K5 - See it at---&gt;<A target="_blank" HREF=http://www.blazzinor.alloffroad.com>http://www.blazzinor.alloffroad.com</A>
     
  10. Jason73K5

    Jason73K5 1/2 ton status

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    BlazzinOR, I just dropped in a TBI motor this weekend and am getting ready to tackle the fuel pump issue. I'd like to check out some pics of your setup if you get a chance.
     

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