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What are the best headers for my 502?

Discussion in 'The Garage' started by Halfnut, Feb 22, 2006.

  1. Halfnut

    Halfnut Newbie

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    I'm putting a 502HT in my '89 3500 CC to tow with, with the edelbrock EFI conversion. I want headers, but I'm not sure what to pick. Since it's the older style chassis, my choices seem to be limited. I've ruled out the stainless Edelbrock because they are shorty headers, even though I'd like SS for the heat resistance. Are the Doug Thorley tri-Y headers the best option? I've read comments that the tri-Y design is not the best for low speed power, others say it is the best. Does anyone here have experience with this? Are there any other good choices for this truck? Is there a 4 tube header made, or any long headers in stainless? TIA
     
  2. Halfnut

    Halfnut Newbie

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    Anyone?
     
  3. Seventy4Blazer

    Seventy4Blazer 3/4 ton status

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    welcome to CK5, i wish i had an answer for you, but i have no BB time under my belt. some day...

    TTT for ya though....
     
  4. tarussell

    tarussell 1/2 ton status

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    The D/T tri-y's should work well due to the scaveging effect. Stick with a small primary tube size and look into getting a regular set of hedders coated.
    I do not have a part number to give you but there should be plenty of brands that offer a set for the K/V series solid axle trucks .

    Question : what is the "HT" in the 502HT engine you have ? Is GM advertising the truck version of the 502 as a high torque special ? I am assuming that you are using the low compression 502 that was intended for an upgrade for the 454's in pull trucks.
    Tom
     
  5. mlaux

    mlaux 1/2 ton status Premium Member

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    Stock cast iron manifolds for my money. If you REALLY want headers go for the thickest flange you can find. With 502CI I don't think you will notice the 25 HP one way or the other, but I bet you'll notice the tick...tick...tick... from the header leaks. All that said, I had a set of thorley headers on a 454 and they were the best set I have ever owned (never leaked once).
     
  6. Lonnie P

    Lonnie P Registered Member

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    Based on the power & rpm range of the motor, 1-3/4" or 1-7/8" would be ok. Smaller will yield better midrange torque (likely what you want/need), whereas the larger favor high RPM power (I'd use 1-7/8" in a car). I believe the 1-3/4" are the easiest to find for trucks & will likely be your best option.
     
  7. ryoken

    ryoken Puppy Fabricator Premium Member GMOTM Winner

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    thats a relative question to money ya want to spend... :haha:

    you can have some SS's made up at quite a bit of change, usually $700 to 1000.. Stans makes some nice stuff, they do the Tri Y too...

    everything i've read says the Tri Y is set up for good lowend torque with a small sacrifice to topend as opposed to long tube... i would think the big advantage would be fit..

    for the ultimate setup having JetHot coat whatever you get and prior-fit would be best, unless you go SS.. tho the Thorley's apparently have a good ceramic coat, i've also heard JetHot is unbeatable... they do carry a pretty large line of inhouse coated headers...iirc, not Thorleys tho... not sure if they have a Tri-Y style...
     
  8. Leadfoot

    Leadfoot 1/2 ton status Premium Member

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    The 502 is a tall deck motor. You may have a problem with traditional BBC headers as the heads sit higher and furthur out. You may have to find headers for a tall deck 427, as to not hit the framerails, or you can notch your frame as some of the guys I pull with have done.

    This is just something to keep in mind.
     
  9. JanneB

    JanneB Registered Member Premium Member

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    Why do you think the 502 is tall deck? I have one and it is not.
     
  10. tarussell

    tarussell 1/2 ton status

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    Agreed - 502 has a 9.8" deck height which equals standard deck block with a 4" stroke.
     
  11. Lonnie P

    Lonnie P Registered Member

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    The 502 is indeed a std deck motor.

    Also, I have used the Hedman long tubes with a tall deck 427 & they fit in the 73-87 frame without any issues.
     
  12. Halfnut

    Halfnut Newbie

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    Thanks for the opinions, everyone. Doug Thorleys sound like the best choice, so I'll start looking for a source.

    How good is the stock coating from Thorley? I want at least 3 years' use from them without reworking them.
     
  13. Greg72

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

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    You should be able to get the Thorleys from Summit (I did)

    The coating lasted pretty well on mine so far, but if you drive it in the snow/salt I wouldn't expect much.....
     
  14. Leadfoot

    Leadfoot 1/2 ton status Premium Member

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    My bad.

    For some reason I was thinking the 502 had the same deck height as the 572.
     
  15. Burt4x4

    Burt4x4 3/4 ton status

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    I run DThorleys on my 454. The shinniny coating is now dul but I like them better that way. The flanges on the DT heders is VERY thick so warping shouldn't be an issue.
    I only have a few hundred miles on them but so far so good.
    Oh and the Tri-Y design is for lowend only...you won't see high RPM engines with a tri-y design heders...well you shouldn't hahahaa.
    Good luck
     

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