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Thread: Expert opinion needed for choosing the propper valve spring

  1. #1
    Junior Member SHOW GUEST
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    Last edited by EJ48315; 05-12-2018 at 09:17 AM.

  2. #2
    Senior Member RACING JUNKIE
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    Since no one has answered this question, i'll give it a shot with what i use. i use 240 lbs seat pressure and change them out when they get down too 220 lbs. The one thing i question though is the 1.805 installed height. You're looking at .630 lift and most roller springs coil bind at 1.180, that leaves no room at all. I have 2 rollers 1 @ .625 lift and the other @ .668 lift and i have the spring heigth set @ 1.950 with .100 long valves.

    JMO

    Zip.

  3. #3
    Senior Member MASTER BUILDER
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    A -9 cam is a racing cam.140 and 400 will not keep the lifters on that cam at higher rpm.Putting more spring on the valves you have would cause another problem,both could cause bad things.Bill.

  4. #4
    Senior Member MASTER BUILDER TheEngineer's Avatar
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    A closed set pressure of 140 lbs would "only" work for a hydraulic roller cam with the lift in the low .500s, not a solid roller (SR) with the lift at the valve in the 600+ range.

    With my SR cams for SBCs, I've been using PAC-1243 springs. Which install at 1.900, w/ 240 closed seat pressure, 625 open and coil-bind at 1.100. That in-turn allows for .700 lift at the valve without any problems.

    The .100" longer valves should work to achieve the 1.900" installed height, which is typical for the SR cam valve springs. And, I would not settle for anything less-than the 1.900 installed height.

    Warren

  5. #5
    Senior Member MASTER BUILDER TheEngineer's Avatar
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    Call Comp "Cam Help" and I bet they'll recommend much-more closed set pressure than 140 for a SR cam with .600+ lift.

    Warren

  6. #6
    Senior Member RACING JUNKIE
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    Quote Originally Posted by EJ48315
    I told my situation to one of the tech guys at summit and he directed me to comp 953-16 springs.


    Specs: COMP Cams 953-16

    Recommended Camshaft Style Roller solid
    Installed Height (in) 1.900 in.
    Seat Pressure at Installed Height (lbs) 148 lbs.
    Open Height (in) 1.250 in.
    Open Pressure (lbs) 455 lbs.
    Dual
    1.535 in. Outside Diameter
    496 lbs./in. Rate
    1.085 in. Coil Bind Height


    I plan to swap out the .060 cups for .015 shims and use +.050 offset locks which would put my installed hight dead on at 1.9"
    First and formost Summit and Jegs, sales people are not good tech people they are there to sell parts.
    As mentioned in the engineer's above post compCams will have the answer, but i'll save you the trouble of calling them.

    The valve springs recommended for the cam you have is P/N 943-16. these springs have a seat pressure rating of 240 lbs @ 1.900 installed height and a coil bind of 1.180.
    I looked up you cam at Comp Cams (12-900-9) (288A-R6) and these were the recommended springs, i then looked the springs and the above #'s came from the spring discription.

    Zip.

  7. #7
    Senior Member MASTER BUILDER TheEngineer's Avatar
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    Quote Originally Posted by zipper06
    Quote Originally Posted by EJ48315
    I told my situation to one of the tech guys at summit and he directed me to comp 953-16 springs.


    Specs: COMP Cams 953-16

    Recommended Camshaft Style Roller solid
    Installed Height (in) 1.900 in.
    Seat Pressure at Installed Height (lbs) 148 lbs.
    Open Height (in) 1.250 in.
    Open Pressure (lbs) 455 lbs.
    Dual
    1.535 in. Outside Diameter
    496 lbs./in. Rate
    1.085 in. Coil Bind Height


    I plan to swap out the .060 cups for .015 shims and use +.050 offset locks which would put my installed hight dead on at 1.9"
    First and formost Summit and Jegs, sales people are not good tech people they are there to sell parts.
    As mentioned in the engineer's above post compCams will have the answer, but i'll save you the trouble of calling them.

    The valve springs recommended for the cam you have is P/N 943-16. these springs have a seat pressure rating of 240 lbs @ 1.900 installed height and a coil bind of 1.180.
    I looked up you cam at Comp Cams (12-900-9) (288A-R6) and these were the recommended springs, i then looked the springs and the above #'s came from the spring discription.

    Zip.
    What is the possibillity of zipper06 and I both being wrong on this issue???? :shock:

  8. #8
    Senior Member MASTER BUILDER
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    Engineer & Zip, definitely not wrong about the springs, but the next question will be why the roller lifters went bad so quickly and wiped out the lobe on the camshaft.

    EJ48315: Just because the springs that the tech guy sold you physically fit, doesn't mean that they are the correct ones for the application and will not cause you other problems. It is not all about higher RPM's, as the ramps on the solid roller lifter camshaft are steeper than the ones on the hydraulic camshaft. This causes the valve to be thrown off of the seat and with your heavier valves it causes the roller lifter to not stay in contact with the camshaft when it goes to close the valve. This causes the roller lifter to bounce on the cam lobe and will damage the roller bearings in a very short time and will in turn cause the roller lifter to fail which will then wipe the lobe on your camshaft. Something else that you might try, that is not used very much anymore because the valve spring technology has gotten so much better, is a rev kit. The rev kit installs on top of the roller lifters to the bottom of the heads. This will be extra spring pressure on the roller lifters and will keep them planted on the camshaft.

    Just a thought,

    Bill Mitchell

  9. #9
    Senior Member RACING JUNKIE
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    My thoughts?? YOUR HARD HEADED!

    Listen to Zip and what the others have been telling you.

    Gezz man, what part of this dont you understand???

    "The valve springs recommended for the cam you have is P/N 943-16. these springs have a seat pressure rating of 240 lbs @ 1.900 installed height and a coil bind of 1.180.
    I looked up you cam at Comp Cams (12-900-9) (288A-R6) and these were the recommended springs."

    Using cheap valves & weak springs is a recipe for disaster with a solid roller.
    JMO, CP
    ***IN GOD WE TRUST***

  10. #10
    Senior Member RACING JUNKIE oldandtired's Avatar
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    Quote Originally Posted by EJ48315
    Quote Originally Posted by sp2816
    Something else that you might try, that is not used very much anymore because the valve spring technology has gotten so much better, is a rev kit. The rev kit installs on top of the roller lifters to the bottom of the heads. This will be extra spring pressure on the roller lifters and will keep them planted on the camshaft.

    Just a thought,

    Bill Mitchell

    Thanks Bill :wink:
    Good point, but 90% of people who use a rev kit do not need it. Unless you are road racing to 9500 or drag racing to 10000, today's springs will suffice with a proper replacement schedule.
    JMO Dave
    Dave
    http://www.racingjunk.com/profile/343797
    "All that is necessary for the triumph of evil is for good men to do nothing" Edmund Burke


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