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BBC head ???

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by 77fixer, Oct 6, 2002.

  1. 77fixer

    77fixer 1/2 ton status

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    I have a 454 that I plan on stroking to put in my Sub, but it has rectangular port heads. What came from the factory with some good oval port heads. What is a peanut port and how do I identify(avoid) them. I probably want open chambers to avoid too high of compression.
    I like the Performer heads except the price. Of course, depending on what the JY wants for the heads plus a rebuild I might want to look at them anyways.
    Let me know what you think,
    Brett
     
  2. thatK30guy

    thatK30guy 1 ton status Premium Member

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    Check out the Merlin heads from World Products. They are cheaper than the Edelbrocks. They are cast iron instead of aluminum, but still outflow the Edelbrocks, too. /forums/images/graemlins/wink.gif
     
  3. 77fixer

    77fixer 1/2 ton status

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    I want to build this engine for torque and I thought that smaller ports and valves are what I want. I think that the heads I have now are too big.
    I really like the vortec heads with their 2.06 intakes, but I worry about the small chambers.
     
  4. Sandman

    Sandman 3/4 ton status Author

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    I wouldnt sweat the Torque issue. BBC's already have so much, its hard to screw it up. It is much easier to ruin the torque in a SBC. Run some computer simulation if possible and you'll see what I mean.
     
  5. nvrenuf

    nvrenuf NONE shall pass! Premium Member

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    Take a look at early to mid 70's GM heads with casting numbers ending with #781 or #049. They are regular production heads found on trucks, wagons, Impala's, etc. These heads are standard oval port design with the small valves so they will make nice bottom end torque and still flow well up to around 5500 rpm.

    The rectangular port heads that you have will not begin to flow well until around 4000 rpm so (as you already know) they will not work well for a lower rpm torque application.

    Be careful the later (pre-Vortec) heads do not flow well at all above 4000 rpm. I realize you may not be looking for a high rpm motor but the poor flow characteristics may poorly offset other mods you will make to the motor.
     
  6. thatK30guy

    thatK30guy 1 ton status Premium Member

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    Oh yeah!!! The 049 heads are the "keepers!!!" /forums/images/graemlins/wink.gif These are hard to find though. /forums/images/graemlins/frown.gif

    I know Shawn has a pair of these 049 heads, but don't know if he would part with them or not. Wouldn't hurt to ask. /forums/images/graemlins/wink.gif
     
  7. nvrenuf

    nvrenuf NONE shall pass! Premium Member

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    Yeah, the #049's are sweet! The #781's are identical so if you find a set grab them, just another case of multiple part numbers that are the same thing.
     
  8. bablazer73

    bablazer73 1/2 ton status

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    i agree with nvrenuf and k30 guy. "049" 1973 heads. also "781" 1974. I also show a "783" more common 70-76, but my book doesn't show chamber size. but should also be 110-112.
     
  9. thatK30guy

    thatK30guy 1 ton status Premium Member

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    According to my references, the 049 heads are a 110cc and available only in '73.

    The 781 is also a 110cc and available only in '74.
     
  10. POWERMAD

    POWERMAD 1/2 ton status

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    Do you have the specs for the 049 castings.
    All my stuff only shows years and application.
    I have a set of these on my 73 and when it goes to 468 I am going to take them in and have 2.191" seats put in.
    With the cam and everything else these heads should work well.
     
  11. thatK30guy

    thatK30guy 1 ton status Premium Member

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    According to my book:

    2.06 intake / 1.72 exhaust valves
    casting number 353049
    110 combustion chamber volume
    came out of 454 engines
    available only in '73
     
  12. POWERMAD

    POWERMAD 1/2 ton status

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    That much I know, I have the same thing. /forums/images/graemlins/laugh.gif
    What I want to know is the runner size. Aren't they somewhere around 310cc's?
     
  13. nvrenuf

    nvrenuf NONE shall pass! Premium Member

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    I have a few books at home and it seems like one of them have runner volumes. I'll look and post it this evening after work.
     
  14. POWERMAD

    POWERMAD 1/2 ton status

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    Cool Thanx.
    I am trying to get as much info as possible to get an idea on how much power it will make.
     
  15. nvrenuf

    nvrenuf NONE shall pass! Premium Member

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    I have a Desk Top Dyno program at home also, once you've decided on your final combo I can run the numbers if you want.
     
  16. POWERMAD

    POWERMAD 1/2 ton status

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    I recieved these cool links, check em out. /forums/images/graemlins/thumb.gif
    Polishing a set of sneakers.
    Rect port vs. oval port
    Oh the runner size is 255 cc's and the chambers are 119cc.
    on a set of 049's.
    This is my combo (on paper anyway)
    I am punching it out to 468, comression ratio about 9.5
    The cam is a Comp cams grind, 226/234 @.050"
    .544/.564 lift.
    An Ebrock performer RPM intake and 850 Q-jet will top it off.
    It looks like the heads will be a killer match to the rest of the plant. That should put it in the 450hp range .
    I can't afford a set of Merlins and I got a deal on getting bigger valves put in and unshrouded for $125 a head. $160 for valves and a few more bux for mis stuff. Spend a few hrs cleaning them up . I can afford that. /forums/images/graemlins/cool.gif
     

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