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TBI Swap (Intake Adaptation Questions)

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by txbluethunder, Nov 7, 2002.

  1. txbluethunder

    txbluethunder 1/2 ton status

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    Who has information on the modification of the stock tbi intake to make it bolt up to 79-85 heads? I've read something about the four center bolts need modified but i'd like more info if anyone has it.

    also

    i've got the money to buy a painless wiring harness for the tbi. i've got the entire wiring harness from the truck i pulled the tbi off of. would this still be a worthwill purchase or would i be wasting my money since i've already got all the wiring?

    thanks...
     
  2. dyeager535

    dyeager535 1 ton status Premium Member

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    I'd imagine a search here is in order for info on Painless.

    My thoughts are keep it stock. Anything less is uncivilized.
     
  3. txbluethunder

    txbluethunder 1/2 ton status

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    actually i've been doing lots of searching...but for the painless question i'm really asking opinions of those who have performed the swap.
     
  4. jmd

    jmd Registered Member

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    You would be wasting your time buying a Painless harness. They're fused wrong, and if you have an OEM harness, you're all set w/ a little work.
     
  5. imiceman44

    imiceman44 1 ton status

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    I don't recommend the painless wiring, because it's wired different, and too expensive, I like the EZ wiring because it's GM style, and cheaper, but I would still go for a OEM harness if available.
    I had a 73 that I converted to 80 style harnes, took one day with both harnesses out of the trucks to combine them and reinstall them.
     
  6. azblazor

    azblazor 1/2 ton status Premium Member

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    I have TBI on a 79K5 and we did my sons 77 Sub. I think the factory harness is perfectly acceptable. Its way cheaper and as long as you have a factory wiring manual its very easy to figure out.

    Modifing the TBI manifold for the olders heads is pretty easy also. ( TBI manifold - the 4 center bolts are straight down, Carb manifolds - the 4 center bolts have the same angle that all the other manifold bolts do ) Some guys just brill out the holes at the proper angle to put the manifold bolts in. And then they use some method of angled washers or spacers to have the bolt heads seat. I and many others machine or grind the surface perpidicular to the newly drilled angled bolt holes. This allows the bolt head to seat flat. The only hard part is that the intake runners raise up on either side of the 4 center bolts such that it is a narrow space to work in. Some machine shops will do the work - others won't touch it. I reworked ours with a drill bit and a dremel tool. Using your eyeball for the angles worked well for me. Just take your time and keep trial fitting it until everything works. Be careful that you don't cut into the air runners or hog out the hole TOO much, such that the bolt heads don't seat or that there would be an issue of a vacuum leak. It sounds a LOT harder than it really is.
    OR
    You can buy an adapter to mount the TBI to your existing 4BL manifold - but then you have some issues with bolting up the sensors and components that fit on the TBI manifold.
    Mark
     
  7. txbluethunder

    txbluethunder 1/2 ton status

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    cool...thanks for the info...and if you have any pics that would be awesome...
     
  8. mattyblazer

    mattyblazer 1/2 ton status

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    A couple of years ago I put a late model 350 in an 81' suburban, and had to make the angle for a carburated intake (opposite), I just streched the hole swith the correct drill bit, no angle grinding, mabey just some RTV blue around the bolts on the way down, worked out fine...
    My buddies tow trucks are all mid 80's v8's and he tried the painless kits and he says that they are O K if you have no other choice but stick with the factory harness if possible, the painless harness has to much extra crap on it.

    Matt
     

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