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TBI heads

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Adub, Nov 19, 2002.

  1. Adub

    Adub 1/2 ton status

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    How big are the combustion chambers on stock 89 TBI 350 heads. I have a set of Vortecs to put on and I want to know how my compression ratio will be affected.
    Thanks
    AW
     
  2. Charly

    Charly Registered Member

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    From all the research I have done....they are 76 cc.

    There are many online charts of GM chamber volumes, but I only found one that lists anything for the TBI heads.
     
  3. bluboti

    bluboti Registered Member

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    Thats a good ?What cc are the vortecs? I have a tbi also would like to do the vortec swap.
     
  4. Sandhills Blazer

    Sandhills Blazer Registered Member

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    The Vortecs or 64cc.
     
  5. unsane

    unsane Guest

  6. dyeager535

    dyeager535 1 ton status Premium Member

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    There are also 58CC(?) 305 Vortec heads apparently, though I've never bothered looking.

    Slightly off-topic, but some magazine mentioned that there are two different exhaust valve seat styles (I'd guess press in and flame hardened) and one flows worse than the other. I *personally* don't buy that, however, I guess its something else to think about before purchase.
     
  7. Adub

    Adub 1/2 ton status

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    Yeah I read that valve seat thing too. 305 TBI heads were 58cc but I have heard 76 and 64 for the 350 truck heads. I dont know
    AW
     
  8. dyeager535

    dyeager535 1 ton status Premium Member

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    The best way would be to grab a casting number off of one of your heads and check it on one of the various online "decoders". Not sure if you can see any casting numbers as installed on the engine without pulling a valve cover, but if you can, that would be your best bet.
     

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