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Help me pick a cam...

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by txbartman, Dec 18, 2001.

  1. txbartman

    txbartman 1/2 ton status

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    Okay, I am installing a base 350 crate from Scoggin-Dickey. I am going with Edelbrock performer intake and TES or Shorty headers. I was planning on going with the matched Edelbrock cam. Here are its specs:

    Duration: 278 intake/288 exhaust
    Duration at .050: 204 intake/214 exhaust
    Valve lift: 420 intake/442 exhaust
    Lobe: 112 degrees

    I talked to Comp Cams and they recommended cam 12-231-2:

    Duration: 250 intake/258 exhaust
    Duration @ .050: 206 intake/214 exhaust
    Valve Lift: 432 intake/ 453 exhaust
    Lobe: 111 degrees

    What do you guys think here? Or would you recommend another? I have heard the 260H is a good one, too. Here are its specs:

    Duration: 260 intake/260 exhaust
    Duation @ .050: 212 intake/212 exhaust
    Valve lift: 440 intake/440 exhaust
    Lobe: 110 degrees

    I don't know anything about cams, so your advice is essential and needed! Thanks!!

    Brian
    Check out <a target="_blank" href=http://tx85gmcguy.alloffroad.com>My Jimmy</a> with all her projects!
     
  2. Andreas

    Andreas 1/2 ton status

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    The one Comp Cams recommended is from their Xtreme 4x4 line. The X4 250 H. A very good cam, but too mild imho. I would pick one step bigger from the Xtreme 4x4 line. The 12-235-2 or X4 254 H. Specs on it are as follows:

    Advertised duration in/ex: 254/262
    Duration @.050 in/ex: 210/218
    Lift at valve in/ex: .447"/.462"
    Lobeseparation: 111 degrees

    It´s rpm range is 1000-5200.

    I would also buy rollertip rockers [​IMG].

    /Andreas

    406cui of pure sh*t[​IMG]
     
  3. marv_springer

    marv_springer 1/2 ton status

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    I like the dual pattern cams better, so I wouldn't pick the 260H.

    I'm running a 355 w/ Vortec heads, and I chose a Summit cam that is identical to the Edelbrock 278* you describe. I installed it 4* advanced and it runs great! Max rpm ~5000.

    Marv
     
  4. mudddog91

    mudddog91 1/2 ton status

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    I agree about the comp cams 4x4 extreme cam.its like an RV cam on steroids!Im running the 12-235-2 in mine right now and it has awsome throttle response and more torque than I can use at one sitting!Real smooth idle and has good power to my redline.
     
  5. Liberator

    Liberator 1/2 ton status

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    I also called Comp Cams and they recommended the 12-231-2 (the 250 grind). I was worried about over-camming with my stock heads. After careful consideration, that's the cam I just ordered from Jegs. The rpm range was 600-4600 which I though would suite my wheeling style. Should be here Thur or Fri. When I get it in and test it, I'll post to give an update.

    Then again, I've been running a 305. So the difference between the 305 that I blew and the 350 that's going in will be huge anyway!

    Bo

    If it breaks, it wasn't good enough!
    http://coloradok5.com/gallery/liberator
     
  6. Twiz

    Twiz 1/2 ton status

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    Short duration (at .050) and high(er) lift is the way to go. It's ruff on the valve train ,increases stress in the lifters, push rods, rockers, studs (if pressed in) and tuff on the springs. (ever spec out a cam by G.M.? They are really kind to the valve tain, this is from the guys the designed the block) But, if the RPMs are kept low, the valv train should hold up with-out problems. Higher lift, with the same duration numbers, gets the valve off the seat quicker. This helps the freash intake-charge fill the chamber (higher ratio rocker-arms do the samething)

    With "shorty-headers" the 4x4 cam would probably be the way to go. The 4x4 cams favor the exhaust more-so than standard cams, so with less-than a ideal exhaust sys, a bit more exhaust timeing would help scavange the exhaust better.

    Ask the cam guys (tech-line), they know better than I do. If given the optoin, pick the one with lower duration numbers and higher lift.

    Therory based on Twiztid's world.


    <font color=blue>Wow factors
    A SBC (4" X 3.48") with 2" intake-valve at 6,000 RPMs:
    1- The piston reaches a maximum speed of 60 MPH
     

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