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Son needs K5 help

Discussion in 'The Garage' started by triumphcorvair, Apr 4, 2006.

  1. triumphcorvair

    triumphcorvair Newbie

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    My son just called from his shop class and his shop teacher told him he needs exhaust manifolds for his K5 Blazer. It seems the ones he has are warped. He wants to install headers which is ok with me. He has a 4wd 83 K5 Blazer (noAC) to which he is installing a rebuilt 350 engine. I have to give him credit he's done most of the work himself. Any recommendations on headers? I just want to make sure they will fit. I found some on eBay, 1/4" flanges, 1 1/2" tubes and 3" collectors. The add says they will fit a 67-87 C5 & K5 Blazer/Jimmy.
    Any comments and/or suggestions are welcomed.
    Many thanks!
     
  2. clarkjw24

    clarkjw24 1/2 ton status GMOTM Winner

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    Shortys from a chevelle are best for auto trannys. If its a manual I'm pretty sure he'll need to run the long tube headers. As far as brand, cheapest always wins with me.
     
  3. BizeeB65

    BizeeB65 1/2 ton status

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    you can search sites like summitracing.com or jegs.com and find part numbers for headers that fit that year K5. The only problem I can imagine is how those headers fit in the engine bay, as the trucks are slightly different thru that wide range of years (67-87).
     
  4. ProJunkRacing

    ProJunkRacing 1/2 ton status

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    i might have a set of manifolds if you want them like 25 dollars plus shipping i am in IL
     
  5. triumphcorvair

    triumphcorvair Newbie

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    Many thanks for the offer.
    I'm going to see him after school to find out the latest.
     
  6. ProJunkRacing

    ProJunkRacing 1/2 ton status

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    yeah i have hedders on mine i dont know where you are from but my friend has a 89 k5 that he got hedders for and they fit like ass he said if he had known shortys would not work well with the y pipe he would have got long tubes i have longs on my truck dynomax ones about 100 bucks from advance auto i dunno where you are from but just a suggestion
     
  7. goldwing2000

    goldwing2000 Guest

    Two things:
    ~1/4" is too thin for the flange. You'll be blowing out gaskets constantly.

    ~personally, I would stick with manifolds. You get better low-end power. If the manifold is ONLY warped and not cracked or has the studs completely rusted away, you can flatten the mounting surface back out with a belt sander. If you don't have a belt sander large enough, call around to some cyl head shops. They should be able to hook you up pretty cheap.
     
  8. 87BrnRsd

    87BrnRsd 1/2 ton status

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    Long tube headers are going to give you more low range torque than shorties or manifolds. Manifolds are junk and are a large power restriction. Shorties typically produce higher horsepower numbers in the high rpm's whereas long tubes headers are more practical for offroad applications where you want more torque at lower rpm's. Check with jegs, summit, or a local store like autozone. Should be no problem to find a decent set of headers for under $150.
    -Harrison
     
  9. goldwing2000

    goldwing2000 Guest

    I think you got that backwards.
     
  10. dontoe

    dontoe 3/4 ton status GMOTM Winner

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    Don't forget, hooking headers up to a stock system is a pain.
     
  11. Russell

    Russell LB7 Tahoe Status Premium Member GMOTM Winner

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    I'm personally of the belief that for the amount of power most guys run in their engines, manifolds are perfectly fine.

    I've run both headers and manifolds on the same truck, and switching between I was unable to tell any difference in power.

    The headers were always blowing out gaskets, and even when they were sealed up well they always had an irritating ticking sound to them under hard acceleration. Certainly much louder when you get on the loud pedal though!

    The manifolds sealed better, and never ticked, so I'm planning to go back to manifolds pretty quick here. Better for my 02 sensor anyways :)
     
  12. mxfireman

    mxfireman 1/2 ton status

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    Headers were kind of a pain like everyone is saying I have to constantly check mine don' for get about smog if you have it in your area.
     
  13. RingMaster4x4

    RingMaster4x4 1/2 ton status Premium Member

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    The thicker the flange the better.
     
  14. dyeager535

    dyeager535 1 ton status Premium Member

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    Actually in most applications, throwing out of the box headers on, long tubes are better all around, with as mentioned the shorties doing better up top.

    It's all about scavenging, log style manifolds simply aren't as effective as long tubes.

    The only advantage to running manifolds is (potentially) longevity.
     
  15. goldwing2000

    goldwing2000 Guest

    K.

    Every dyno sheet I've seen with a comparison, the long-tubes make more HP but at a higher RPM.

    :dunno:

    It's not worth arguing about, though.
     
  16. R77K10

    R77K10 Banned

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    but do you really need hp in a heavy rig

    not really

    need low end torque more than anything else

    to me i see no point in having more HP at higher RPM unless youre running a light car and on the track for racing only


    and imho headers are a pain

    if you get some then dont go cheap on them or youll be wishing that you didnt after a year or so

    they will leak/burnout, etc., give them time

    junk

    save yourself trouble and just put on some other manifolds on or have the current ones milled straight if they are truly warped- in which in all my years of vehicles i have never seen truly happen, on a sbc anyways

    cracked yes but warped no

    ppl throw good ones away all the time, in fact i have a pair of these manifolds on the scrap load on the 77 k-10 right now, perfectly good ones, commonly scrapped stuff


    also here is what i do;
    with headers i use manifold gaskets
    with manifolds i use no gaskets

    never leak, with all the different engines and vehicles i have had, never a problem doing them this way




    good luck
     
  17. Leper

    Leper 1/2 ton status

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    No gaskets and no leaks, WOW
     
  18. ProJunkRacing

    ProJunkRacing 1/2 ton status

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    yeah that is what i said how no leaks?
     
  19. dyeager535

    dyeager535 1 ton status Premium Member

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    You are right, no need to argue with fact. :)

    http://www.carcraft.com/techarticles/116_0312_test/index1.html

    And all the thorley proponents, look at where the *losses* are compared to the 4 into 1 headers...definitely not good truck motor candidates IMO.

    My favorite quote out of that article: "Even on a stone-stock 350ci small-block Chevy, a simple set of 15/8-inch headers are worth as much as 53 lb-ft of torque and 34 hp." Thats entirely useable in the 3000RPM range it occurred.
     
  20. goldwing2000

    goldwing2000 Guest

    *shrug* Ok. That's one person's study.
     

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