GT40P heads and Headers?

Discussion in 'Technical' started by sixty9santa, Jan 23, 2009.

  1. sixty9santa

    sixty9santa New Member

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    I have a 1976 302 engine project and I'd like to know if GT40P heads will work with Hooker 6901HKR long tube headers?
    I don't mind grinding on the header flanges, using shorty spark plugs and 90degree spark plug wires as long as the headers can work with the heads....please help!
     
    Last edited: Jan 24, 2009
  2. ratio411

    ratio411 Member

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    Scott did it. Only one I know of though.

    He did several posts on it.
    Here is one:
    http://mmb.maverick.to/showthread.php?t=19531

    Do a search on his username and 'hooker'. That should bring up several conversations on how he did it.
     
  3. chirt

    chirt Carlos Hirt

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    i have them gt40ps on mine! but with headman hedders!:)
     
  4. bmcdaniel

    bmcdaniel Senile Member

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    I ran P heads the way you describe but with Blackjack headers.
     
  5. sixty9santa

    sixty9santa New Member

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    bmcdaniel,

    Did you have any issues with park plug wires burning up?

    Also, can anyone help direct me as to what hypereutectic pistons I should get in order to boost compression to something around 9.0:1 with the GT40P heads, preferably something that Summit Racing carries.
    I'm on a budget and some low buck, if there are any, pistons would be a great help.

    I ask this since I have an early (made in May car) 1976 302 with 56k miles and I'm planning on getting GT40P heads, already have a 600cfm carb, already have a Performer RPM intake, already have Hooker 6901hkr headers and a hotter cam such as compcams he268h or the xe256h (or is there a better cam?).
    How much power could I possibly make without new pistons?
     
    Last edited: Jan 24, 2009
  6. bmcdaniel

    bmcdaniel Senile Member

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    The only time I burned anything was when a plug wire popped out of the loom and the boot rotated around on the plug and touched the header. I used shorty plugs on the driver's side and boots/terminals from an electronic distributor cap on all of the plugs.

    302s from 74 - 77 (D4 casting number) had a .023" higher deck height than earlier and later 302s to reduce compression, plus P heads have about 60 - 61 cc chambers. Not sure what your current heads are. Also the cams from that era are retarded timing-wise. I would save a few more pennies and convert to a roller cam.
     
  7. 76Mav77

    76Mav77 [MДυξЯϊςЖ]

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    Do the GT40P heads come off 90s exploders???
     
    Last edited: Jan 25, 2009
  8. 76Mav77

    76Mav77 [MДυξЯϊςЖ]

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    I have a buddy with an exploder engine that im sure he will sell me the heads if they are the GT40P...if i read the mustang forums right.
     
  9. bmcdaniel

    bmcdaniel Senile Member

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    I believe they came on 97-up Exploders. Easy to identify, they have four vertical bars cast into the front of the head. Three vertical bars denote regular GT40 heads. Also the spark plugs stick straight out instead of at an angle like other Windsor heads.
     
  10. scooper77515

    scooper77515 No current projects.

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    If you can find the non P GT40 heads, you will be much happier.

    By the way, I am Scott that was referred to up at the top.

    I used the P heads for several years with headers, but in the end, it just wasn't worth the hassle. I finally went with regular GT40s and have a much easier time with spark plugs.
     
  11. 76Mav77

    76Mav77 [MДυξЯϊςЖ]

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    well then i also heard the earlier exploders had the GT40 heads and later years had GT40p so im not sure
     
  12. scooper77515

    scooper77515 No current projects.

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    It is like 94-96.5 or 97.5 for the non P, then 96.5 or 97.5 up for the Ps. Can't remember when the switch was.

    Just look for the 3 bars on the front (and rear) of the head for the non Ps, and 4 vertical bars for the Ps.

    Then be prepared to put new springs, locks, and seals on them. Those are roller springs, and will eat up your cam in a flat-tappet motor.
     
  13. facelessnumber

    facelessnumber Drew Pittman

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    So if I happened to score some GT40 heads, would I be able to move all that valvetrain hardware from my current '72 small chambered heads of undetermined origin? I have new springs matched to my cam and lifters... Would pushrod length be the same? Any other changes involved when switching to those heads?
     
  14. 76Mav77

    76Mav77 [MДυξЯϊςЖ]

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    OK next question if you have the cash is like edelbrock heads a better way to go or for the money difference is the GT40s out of a bronco better
     
  15. scooper77515

    scooper77515 No current projects.

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    Any aluminum head will be better, if you have the cash.

    But as far as springs and stuff, you are only looking at another hundred bucks or so. Just call your cam manufacturer and ask which springs you need, and order a set. Seals can be had at OReilly, Autozone, Napa, etc for about 15 bucks.

    It is pretty important that you get springs with the correct travel and pressures to match your cam and lifters.

    Not sure if you could use your existing springs and swap them over. Good question...
     

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