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big block questions...

Discussion in 'The Garage' started by 3car, Sep 27, 2003.

  1. 3car

    3car 1/2 ton status

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    when an engine is refered to as either rectangular or oval port,is that the intake or exhaust ports being described?was there a year that a change was made from one to the other,and which is better?thanks in advance!
     
  2. bablazer73

    bablazer73 1/2 ton status

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    The intake ports. Most High performance options were rectangle port. years from 66-73.LS6, LS7, 375 horse 396. 430/435 horse 427's. oval ports were used on all stock and some mild performance engines. The LS5 was oval port. There is also a round port head which was used on the truck engines. There were several different casting of each head. with several different combustion chamber designs.
     
  3. Lonnie

    Lonnie 1/2 ton status

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    Rectangle & oval refer to the intake port sizes. High performance engines were of the rectangle port variety. These engines were also equipped with solid lifter cams & Holley carbs. Notably the 396/375HP, the 427/425HP 454/450hp. Most others were oval port. Truck heads are also oval ports, but often referred to as "peanut ports" as they are even smaller than the normal oval port heads. Oval port heads are good performers for most street engines & generally all engines used in pickups etc., while the rectangle variety is for use primarily above 4000rpm as they do not make good low end torque. Hope this helps.
     
  4. 3car

    3car 1/2 ton status

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    that clears it up...thanks guys.
     
  5. SUBFAN

    SUBFAN 1/2 ton status

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    Look for 'open chamber' oval port heads....
     

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