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Technical Gen 2 (centerbolt) SBC and Vortec heads

Discussion in 'The Hokey Ass Message Board' started by CarProblem, Sep 25, 2019.

  1. CarProblem
    Joined: Sep 25, 2019
    Posts: 1

    CarProblem

    So first the story...

    I've been wrenching for years, but only recently have gotten to the point in life where I wrench for pleasure instead of money or dire need

    One of my pleasure projects is a 65 Impala rescued from a storage unit that needed an engine. I hunted for a (cheap) engine for some time and came up with nothing... then all of a sudden engines galore

    long story short, I have accumulated an engine for the 65, and enough other stuff to shed some light on the SBC Vortec head issue

    The first potential donor engine that I came across was (what I call) a Gen 2 centerbolt 350... which I didn't realize was much different from the Gen 1 variety until I tried to put my intake manifold on it - and discovered that the center intake bolts don't line up

    I did some research on the matter, and discovered what a lot of people discover - some folks out there assume that all of this variety of motor have Vortec heads - which is apparently very wrong.

    I have since accumulated a set of the legendary Vortec heads, and can now speak somewhat knowledgeably about what is and isn't a Vortec head

    So first - Gen 1
    Gen 1.jpg
    valve covers bolt on the outside - all the intake bolts point the same direction

    The non-vortec Gen 2
    Gen 2.jpg
    valve covers bolt down the center (centerbolt) and the center intake bolts are at a (slightly) higher angle than the outside ones (some people say they are straight up - very misleading)

    So now the centerbolt Vortec head...
    heart shape combustion chamber
    the sawtooth casting on the end (very important)
    and entirely different intake bolt pattern with only 4 bolt holes per head (nothing in the middle)
    Vortec 1.jpg Vortec 2.jpg Vortec 3.jpg

    I'm sure there's some technical inaccuracy in all of this... but I hope it helps
     
  2. Atwater Mike
    Joined: May 31, 2002
    Posts: 9,776

    Atwater Mike
    ALLIANCE MEMBER

    My heads on my Gen II ('89 350, out of a pickup) are NON Vortec. Comp cam, Edelbrock intake. Good performance, but I was elated when I found new tech on heads: Vortec 'ain't what they were thought to be'.
    Head technology is leap years above the Vortec plateau.
    So...Until my F100 needs more power, this will do.
    Thanks for the insight.
     
  3. squirrel
    Joined: Sep 23, 2004
    Posts: 43,494

    squirrel
    Member

    it's all pretty off topic for this place...

    Chevy introduced the Vortec name for truck engines several years before the 1996 L31 engine that everyone loves to call the Vortec.

    And the actual Chevy Gen II small block is the 1992 and later one used in the vette and full size cars and camaros, not the truck engine. It has reverse flow cooling, cam driven water pump and ignition, etc.

    The 87-95 truck engines with the center bolt valve covers are only slightly different from the previous small blocks, they are not a new generation. You can waller out the holes in an earlier intake and use it on those engines.

    The L31 engine uses quite a different intake manifold.
     
    Last edited: Sep 25, 2019
    hrm2k and Desoto291Hemi like this.
  4. Fordors
    Joined: Sep 22, 2016
    Posts: 2,171

    Fordors
    Member

    Granted, the L31 heads are out of the HAMB realm, but if anyone did use them on say a 327 for a performance gain keep in mind that their intake bolts take substantially less torque, only 12 ft. lbs.
     
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