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Help: Thorley Header clearance

Discussion in '1969-1972 K5 Blazer | Truck | Suburban' started by Robin, Aug 2, 2002.

  1. Robin

    Robin 1/2 ton status

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    I remember someone installing Thorleys on a 350 and having to cut the driver's side to get it to fit right.

    I finally got the engine on the frame and the driver side header at the collector, does come awfully close to the rear shackle on the front spring (original spring and lift).

    My question is: Does the engine rock enough and the suspenion flex enough to cause a problem? I have about 1/4" between the collector and the shackle.
     
  2. 1Blazin71

    1Blazin71 1/2 ton status

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    I have Hookers on my SBC and with the ORD HD Shackles I have 5/8" of clearance at the flange on the drivers side and never rubbed it. I also never hada problem with these headers and the stock shackles.

    Not quite the info you're after for the Thorleys, but it might help.
     
  3. BAD4WD

    BAD4WD Registered Member

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    I bought some Hedman torkstep hedders for my '71 4x4 & the collectors exit at the middle of the frame, not way down by the shackles, like so many do. One of the best fit hedders I found for the early 4x4's
     
  4. ntaj*ep

    ntaj*ep 1/2 ton status

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    I have some tri-y headers almost exactly like the Thorley headers. I had to use spacers on the pass. side engine mount for them to fit right. /forums/images/icons/shocked.gif What a surprise. My collecters are a little closer than 1/4" from the shackle, I've never had a problem. /forums/images/icons/grin.gif
     
  5. skyblazer

    skyblazer 1/2 ton status

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    Robin, I had the same problem with Thorley 372Y headers, but on the passenger side. My right collector actually touched the lower shackle bolt. Filing the bolt head and the collector flange didn't give me enough clearance, so after talking to Thorley, I cut and welded the collector so that it angled in a bit and cleared everything. They said that it was either that or nothing because they were being bought out at the time and everything was up in the air........outstanding customer service ehh! The tech guy said that cutting and rewelding them would not void the warranty, but the last couple inches of my headers don't look very perty any more. Next time I'll buy headers that are uncoated, fit them and then get them coated. I have some pics in my album if you want to take a look.
     
  6. Robin

    Robin 1/2 ton status

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    Yeah, I meant the passenger side. (brain-fart)

    Anyways, I trimmed the bolt head and the exhaust-side collector and I have some clearance, I just don't know how much I'll need.

    Also, the header hasn't been tightened down yet (I was wanting to know if it would fit before I added the hi-temp silicone to the head side of the header gasket), so tightening it down might give me a little more clearance.

    They did leave plenty of clearance for the front driveshaft... /forums/images/icons/smirk.gif
     
  7. skyblazer

    skyblazer 1/2 ton status

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    I might have had more problems due to the ORD HD shackels. They are longer and thicker and probably caused part of the problem. Three questions?
    - Did you try to call Thorley/what is the status of the company?
    - I ran a post in the Garage section about 383 roller cams, what did you go with in your engine? I've got mine apart and am considering going to a roller cam.
    - Where is Georgetown, TX? I don't have my map handy!
     
  8. Robin

    Robin 1/2 ton status

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    I didn't call Thorley. I got the headers just after the takeover. I ordered mine through a shop in AZ. that had them in stock (most all the other distributors were out-of-stock) and when I got them, they didn't have any header bolts and 2in. reducers. I called Thorley and they sent me the hardware kit and the 2.5in reducers, so I'm mildly pleased.

    As part of my head porting, I did some match porting on the headers which I thought were a little rough. I guess I heard so many horror stories about headers, my expectations weren't very high.

    My machinist recommended a roller cam, but I was trying to keep under a budget so I opted out. If I'd known what I'd end up spending, the extra $200 wouldn't have been anything to worry about...

    G'town is 15 miles north of Austin.

    BTW: When you "adjusted" your header, how much clearance did you leave from the shackle?
     
  9. Leadfoot

    Leadfoot 1/2 ton status Premium Member

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    If it makes you feel any better my Hooker Super Comps would hit the shackle bolt when my engine used to tweak (before I installed ORD's motor mounts). To solve that problem with the stock motor mounts, I ground down the end of the shackle bolt. Does your header hit the shackle itself or the bolt? If it hit the bolt, you can grind it down (within reason) or install it the opposite direction. Mine had the head of the bolt to the outside of the vehicle and the nut toward the middle of the vehicle. I could have turned the bolt around and gained enough room, but the grinder was quicker.
     
  10. skyblazer

    skyblazer 1/2 ton status

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    Robin, I have probably 3/4" clearance now. I just went down and looked at them again and what I had forgotten was that we cut the collector flange off, then cut the reducer pipe at a slight angle and actually welded the reducer to the collector (backwards, flange to the rear). This lengthened the collector and moved the flange to the rear about 2" which gave the shackle ample clearance. Then the flange that was cut from the header was welded to the pipe. Sounds weird, but it seems to work good.
     

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