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Camshaft compatability with TBI...

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by 89GMCSuburban, Dec 24, 2002.

  1. 89GMCSuburban

    89GMCSuburban 1/2 ton status

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    I just replaced the engine in my truck (200 miles on the new stock engine), and with it I put it a new Elgin performance cam. Anyone have Desktop Dyno?? Here are the specs:
    Cam Lift INT=.280 EXH=.295
    Valve Lift INT=.420 EXH=.443
    Lobe Centers INT=107 EXH=117
    SAE Duration INT=271 EXH=280
    .050 Duration INT=204 EXH=214
    SAE Timing BTC=27 ABC=71 BBC=76 ATC=32
    .050 Timing BTC=-5 ABC=29 BBC=44 ATC=-10

    I put the cam in but don't notice any real increase in power except for a loped idle. What's up with that??? This cam is VERY similar to the one installed in a certain 270hp replacement motor for the truck based on a GM Goodwrench stock replacement engine for my TBI.
     
  2. K5on38s

    K5on38s Registered Member

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    Hmmm, What's the power range in the cam....... maybe it'll need a stall converter to "pep" it up a bit /forums/images/graemlins/deal.gif
     
  3. 89GMCSuburban

    89GMCSuburban 1/2 ton status

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    It supposed to be 1500-6000 RPM range..I cruise at 2,200 RPM but don't notice a whole lot of difference.
     
  4. dyeager535

    dyeager535 1 ton status Premium Member

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    Compare those lobe centers to factory GM stuff. I believe all the injection cams (stock, or aftermarket "computer compatible) are up in the 112*-114* range.

    Has a lot to do with vacuum as I recall, what does yours pull at idle?
     
  5. 84_Chevy_K10

    84_Chevy_K10 Banned

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    If that cam lopes, something is wrong. I have a bigger cam than that in my K10 (not much bigger, but bigger) and it doesn't lope at all.
     
  6. YtseJam

    YtseJam 1/2 ton status

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    The Lift on the factory cam is .383 INT. .403 EXH
    So it's not all that much bigger. Your power increase won't be that much greater. You may notice a nicer soiunding idle, andd a noisy PCV valve with the TBI.
     
  7. TopOff

    TopOff 1/2 ton status

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    If you really want all you can get out of the cam, you will need to reprogram the chip.

    www.thirdgen.org

    Have fun!
     
  8. 89GMCSuburban

    89GMCSuburban 1/2 ton status

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    I can check the vacuum for you, I have a guage.
    This cam profile is .003 lift off of a cam that supposedly bumps up the engine to 270 hp, maybe my timing is off...
     
  9. 84_Chevy_K10

    84_Chevy_K10 Banned

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    Don't just focus on lift numbers. Two cams could be very different and have the same lift specs.
     
  10. dyeager535

    dyeager535 1 ton status Premium Member

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    Probably wouldn't hurt to check, from the sound of it, that cam shouldn't "lope" if everything else is right.
     

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