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Tbi ?

Discussion in 'The Garage' started by stayaway, Aug 1, 2005.

  1. stayaway

    stayaway Registered Member

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    hello all I have ? about tbi just built my motor for a 87 k5 and but a small cam in 280duration 486lift with the stock heads 40over with flat tops the prob is it will not idle right have the same motor in my 87iroc and had to have mass air flow recaled but it is tuneport is there a map sensor that I can buy or some way to fool it I did drill a hole in the header and welded a place for the o2 sensor any help would be nice thanx
     
  2. sandawgk5

    sandawgk5 3/4 ton status

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    What is the lobe seperation on that cam. If it is less than 114 or 112 I think it will not build sufficient vacuum in the manifold for the MAP sensor. I believe this is the issue. If I am wrong please let me know guys.

    Ira
     
  3. Codeman96

    Codeman96 1/2 ton status

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    Something with a duration in the 280s is going to have a pretty good chop anyway. A straight 280 Comp Magnum is what I have in my '79 Capri drag car and it sounds nasty at idle.
     
  4. Thunder

    Thunder 3/4 ton status

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    yur running too much duration for the stock chip to handle. You will need a new chip burned for your cam. You will also have to take into concideration what your compression ratio is.
    The stock chip wont run cams much over 212 Dur at .050 (260 total dur)
    LSA 212
    Lifts up to and around 480 will work
    Compression ratio up around 9.2 to 1
     
  5. LongIslander26

    LongIslander26 1/2 ton status

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    Crummy idle

    You can run a cam with those specs, you just need a wider LSA, so your overlap isn't so much, and the engine will produce decent vaccuum. Generally, an over lap angle of 45 degrees or less is what you're shooting for. Check the spec card that came with the cam, otherwise, you'll need to get a chip burned for your PCM.
     
  6. stayaway

    stayaway Registered Member

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    Thanx you guys for all the help will be getting a new chip next week thanx again
     

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