Valve springs for gt-40's

Discussion in 'Fox 5.0 Mustang Tech' started by 352Ford2, Dec 29, 2005.


  1. 352Ford2

    352Ford2 New Member

    Joined:
    Oct 12, 2005
    Messages:
    417
    Likes Received:
    0
    Trophy Points:
    0
    Location:
    Seattle,WA
    What valve springs are people running with their iron gt-40's?

    trying to find something that doesn't require machining, but is not a stock replacement.

    anyone still using the factory retainer/roatators?
  2. Michael Yount

    Michael Yount Advanced Member

    Joined:
    Apr 10, 2002
    Messages:
    9,047
    Likes Received:
    0
    Trophy Points:
    77
    Location:
    Charlotte, NC
    What cam are you running? That should dictate your spring choice...


    Sponsored Ad

  3. 85mcLaren

    85mcLaren Member

    Joined:
    Feb 26, 2004
    Messages:
    41
    Likes Received:
    0
    Trophy Points:
    7
    Pay attention to the keepers. The exhaust valves on the 40s have rotators on them. Some kits will give you the wrong sping kit and you will have the ever popular problem of the rocker trunion hitting the exhaust valve stem....

    Jason
  4. 352Ford2

    352Ford2 New Member

    Joined:
    Oct 12, 2005
    Messages:
    417
    Likes Received:
    0
    Trophy Points:
    0
    Location:
    Seattle,WA
    I am deciding between my stock sd ho cam or a mild aftermarket one.

    I know what you are saying about the rotators, the factory gt-40's have diffrent length springs on the intake and exaust. I am looking to save cash and reuse the locs and retainers.

    So I guess I am looking for springs with an id no smaller that .97", OD in the 1.45 range, that are setup for the rotaters with shorter length on the exaust and longer on the intake, can handle up to .54 lift (some saftly margin I probibly wouln't go over .51) cam, and have enough seat pressure for a roller cam.

    I know I am not the only person that has looked for this.
  5. 352Ford2

    352Ford2 New Member

    Joined:
    Oct 12, 2005
    Messages:
    417
    Likes Received:
    0
    Trophy Points:
    0
    Location:
    Seattle,WA
    Come on

    I know there are other guys on this forum that are running gt-40's


    what springs are you running?
  6. Rick 91GT

    Rick 91GT SN Certified Technician Site Sponsor

    Joined:
    Nov 30, 1999
    Messages:
    9,747
    Likes Received:
    94
    Trophy Points:
    99
    Location:
    PA
    We used some Crane 99837-16 springs with a Crane 2031 cam(now pt 444225) 1.7" Crane Cobra rockers and had no issues at all. I believe we used a 99943 and a 99936 retainer, 99041 lock.

    Once you know what cam you are going to use, then we can pick the components out.... Locks and retainers are cheap, I'd replace them along with the vavle seals.
  7. 40th 2004Stang

    40th 2004Stang New Member

    Joined:
    Sep 30, 2004
    Messages:
    53
    Likes Received:
    0
    Trophy Points:
    0
    Location:
    Kansas City
    When doing some research on this subject, here's what I found from my machinist. We looked at Comp Cams 842 series. They would have to be machined to fit properly on the GT40 heads. We ended up using the TFS 200 kit, because I was using 1.7 RR's and a TFS Stage 1 cam. No machining required and fit perfect. I understand the TFS 100 kit works well too, just depends on what your requirements are.

Share This Page