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Thread: Weak springs?

  1. #1

    Weak springs?

    Hi,

    I have a Crane TR-272/4167-2S-10 cam in my 509.

    The cam card says:

    1967-UP CHEVROLET V-8 396 THRU 454 CU.IN.
    MODERATE COMP. ONLY, GOOD UPPER R.P.M.
    TORQUE & H.P., HIGH COMP. RATIO REQUIRED

    INTAKE @CAM 4167 @VALVE 708
    EXHAUST @CAM 4167 @VALVE 708

    TIMING OPENS CLOSES ADV DURATION
    @ .0195 INTAKE 45 BTDC 85 ABDC 310 °
    TAPPET LIFT EXHAUST 88 BBDC 48 ATDC 316

    @ .050 INTAKE 29 BTDC 63 ABDC 105 °ATDC 272 °
    TAPPET LIFT EXHAUST 72 BBDC 26 ATDC 115 °BTDC 278

    RECOMMENDED RPM
    RANGE WITH MATCHING COMPONENTS
    MINIMUM RPM 4400
    MAXIMUM RPM 7800
    VALVE FLOAT 8500


    So not a street cam, but not a pro-stock cam either.

    The valve spring recommandation:

    Crane-99876

    LOADS:
    CLOSED 160 LBS @ 1.968 OR 1 31/32
    OPEN 490 LBS @ 1.308

    I have installed them on 1.950" which gives 160-180lbs seat pressure new. Few questions. Is this enought as the rpm at finish line is about 7000? Should I upgrade the springs? Spring recommadations for 1.55 size? Heads are with 2.19/1.88 stainless steel valves. I had about 50 runs on new springs and lifters when we took it apart. Springs are now 150-180lbs at the seat. Valve seats and lifters seems to be fine.

  2. #2
    Senior Member RACING JUNKIE
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    I would make sure the springs are AT LEAST at the specs on the cam card...you could lose the whole motor over a cheap (relatively speaking) part. Any doubt in your mind at all I would get new ones.

  3. #3
    Senior Member RACING JUNKIE
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    Is this a roller cam or flat tappet cam?

    Zip.

  4. #4
    Senior Member RACING JUNKIE
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    http://cranecams.com/index.php?show=...01&lvl=2&prt=5

    According to Crane's website, you don't have enough spring.
    -WJ Birmingham

    OneBadGMC.com

  5. #5
    Senior Member RACING JUNKIE jmarksdragster's Avatar
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    Your spring part # should be 99886, not 99876. Big difference. If it were me I would set the heads up with a PAC 1246 spring, but at least get the correct springs. If you are limited to a 1.55 spring, a PAC 1225 would work much better than what you have.
    Mark Whitener
    http://racingfuelsystems.myfunforum.org
    __________

    Good work isn't cheap, and cheap work can't be good.

  6. #6
    OneBadGMC, that's funny. I got exatly the same camcard from 90's which says exatly same things expect the springs are Crane-99876.

    LOADS:
    CLOSED 160 LBS @ 1.968 OR 1 31/32
    OPEN 490 LBS @ 1.308

  7. #7
    Senior Member RACING JUNKIE
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    Maybe they figured out that it wasn't enough spring and revised the website and new cam cards?

    If you can fit a 1.56" spring, go with a PSI CT1227

    http://www.psisprings.com/index.php?...ask=view&id=17
    -WJ Birmingham

    OneBadGMC.com

  8. #8
    Senior Member RACING JUNKIE
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    This is copied from the original post, very confusing.


    1967-UP CHEVROLET V-8 396 THRU 454 CU.IN.
    MODERATE COMP. ONLY, GOOD UPPER R.P.M.
    TORQUE & H.P., HIGH COMP. RATIO REQUIRED


    Moderate comp only, then high comp required? wt?

    I'd go with the springs recommended from crane they know whats best for their cams, or go with a comparriabled set with them same seat pressure, same installed height and coil bind.
    Goodluck, Charles
    ***IN GOD WE TRUST***

  9. #9
    Senior Member RACING JUNKIE
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    Quote Originally Posted by cepx111
    This is copied from the original post, very confusing.


    1967-UP CHEVROLET V-8 396 THRU 454 CU.IN.
    MODERATE COMP. ONLY, GOOD UPPER R.P.M.
    TORQUE & H.P., HIGH COMP. RATIO REQUIRED


    Moderate comp only, then high comp required? wt?

    I'd go with the springs recommended from crane they know whats best for their cams, or go with a comparriabled set with them same seat pressure, same installed height and coil bind.
    Goodluck, Charles
    Pretty sure that means "Moderate competition only" asw you see that a lot in the catalog descriptions. I could be wrong.

  10. #10
    Senior Member RACING JUNKIE
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    Yeah your probably right Todd, that didn't even occure to me.
    Cp
    ***IN GOD WE TRUST***


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