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Who has the Doug Thorley headers on a big block?

Discussion in 'The Garage' started by Zeus33rd, Apr 17, 2006.

  1. Zeus33rd

    Zeus33rd Smarter than you GMOTM Winner

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    Posted in the 73-87 forum too...

    Lookin for some headers for the 454 goin into my '83 K20. I've been lookin at the Thorley Tri-Y's. Does anyone here run a set with a big block? Hows the fit? Any installation problems? Any reason to get anything else of comapreable quality? No cheap ass $129 Headman or Flowtech junk. Getting closer and closer to swap time, Just tryin to get all the bases covered.
     
  2. rcamacho

    rcamacho 1/2 ton status

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    I'm running a pair on my '87 BBC K5. Great quality.
     
  3. k20

    k20 3/4 ton status

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    Running em on mine, no problems except the #5 plug is a little bit of a pain. Even with that pain of a plug, I can change em out in about 20 mins. Fit is fine, some people have mentioned the collector on the passenger side being a problem when running the exhaust, because it points slightly towards the frame rail, but I didnt have any issues.
     
  4. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    Greg72 runs them on his 1st gen. Also, the headman headers are a pretty quality header these days. They aren't made of thin cheap ass tubing anymore like they used to be and they have the thick flanges as well now.
     
  5. Burt4x4

    Burt4x4 3/4 ton status

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    I am running them too. They do discolor after a bit of time but they seam to work great. When I had my truck dyno tested the dyno tech said the Tri-Y design falls on it's face up in the 4800-5000 RPM range...but I don't care cuz my stuff ain't spinin that fast anyway. Good low range header :D
    ANother I like on my SBC was Hedmen Elite series, thick flanges and nickle coating that did not discolor..if that matters to you?
     
  6. Chevy305

    Chevy305 6 Lug 14bsf Status Premium Member GMOTM Winner

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    I am looking to do headers because I have $$ to burn and I want the best quality, but I want to be able to spin my engine into the 5600rpm range. I'm sure they are better than the stock manifolds anyway. How much more power can be expected from a set of Doug Thorleys?
     
  7. jays68yak

    jays68yak 1/2 ton status

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    Ill second the hedman qaulity. The ones that I have in my blazer are nice cuz they dont have the tipical header flange at the collector. Its got a ball end so that you can move the exhaust a bit to get it to line up or what not.
     
  8. Burt4x4

    Burt4x4 3/4 ton status

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    Lots of lowend power..duno any numbers to give you..google it :D
    Basically the Tri-Y design, Thorley or others, will not be a good choice for high RPM applications...like a car. For a trail rig the Tri-Y is a torque builder and no need for high RPMs...unless your blastin the dunes or a mud hole but that is just from time to time so...
     
  9. Chevy305

    Chevy305 6 Lug 14bsf Status Premium Member GMOTM Winner

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    Ok I found that they can give you about a 12-17% increase. Plus the mileage gains too. But I now have a dillema about the Thorleys. There are 2 part #s that match my application: 300Y and 364Y The 300Y is both driver and passener are full length, while the 364Y has the driver full length but the passenger not quite full length. look at the pictures:
    This one is the 364Y:
    [​IMG]

    This one is the 300Y:
    [​IMG]
     
  10. Chevy305

    Chevy305 6 Lug 14bsf Status Premium Member GMOTM Winner

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  11. ChickenRammit

    ChickenRammit 1/2 ton status GMOTM Winner

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    You Didnt Mention What Truck Youll Be Installing The Headers In. I Have An '86 K5 And Mine Are Like The 364y Except On Mine There Is A Port On The Front Pipe On Each Header That Recirculates Exhaust Fumes Through The Air Injecter.
     
    Last edited: Apr 18, 2006
  12. Chevy305

    Chevy305 6 Lug 14bsf Status Premium Member GMOTM Winner

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    oh, sorry. I have a 85 K10 with a clutch and no emissions equiptment at all. I have a 2 1/4in duel exhaust on there now. I really want to know if that little bit of extra passenger header will matter in the greater scheme of things.
     
  13. 88-383

    88-383 1/2 ton status

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    I just installed a set on my 90 5.7 K5 tonight. I can tell you the fit was perfect! no BFG needed. They went right in and lots of room for angle or straight plugs. The Y-pipe slipped together without any effort at all. The included hardware was complete and the gaskets were of quality.

    I know you asked about the BB stuff, but I'd be willing to bet you could expect no less. The Thorleys are available with a high temp coating for mo money mo money.

    Just my 2cent

    Kelvin
     
  14. Desert Rat

    Desert Rat Fetch the comfy chair

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    Joe, I don't have a big block, and I didn't go with the Doug Thorley brand per se. I went with Doug's Headers. The Doug Thorley company is owned by the ex-wife of Doug Thorley now. Doug Thorley split and started up his own company again under Doug's Headers (http://www.dougsheaders.com/) I bought a set of these and had some install problems. See these threads:

    http://coloradok5.com/forums/showthread.php?t=155978
    http://coloradok5.com/forums/showthread.php?t=164736

    However, the quality was excellent and they are only offered in thermal coating.
     
  15. Chevy305

    Chevy305 6 Lug 14bsf Status Premium Member GMOTM Winner

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    After reading about you guys having trouble with your shackle to header collector spacing, I think I will spring for the 364Y because the passenger side won't reach the shackle.
     
  16. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    I run the 304-Y on my 396BBC in a '72K5.

    They fit pretty well but have a bizarre angle on one of the collector flanges.... I have good pics of the headers and installation in my .sig gallery link.


    :usaflag:
     

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