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  1. #1
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    2 out of 2 members liked this post. Yes Reputation No

    Valve float analysis in slow motion.

    What you will see in this video is valvespring harmonics, valvespring rotation, valve bending and some float.



    What's important to note is that it is hard to imagine such a stiff spring act like jello, at 8300 RPM the spring looks like a childs toy bouncing around. This bouncing is harmonics and actually needs to be tuned out of the valvetrain using the right spring stiffness and valve stem length and other factors etc...

    Valvespring rotation is when the actual spring and retainer spins in place, you can clearly see that. This causes premature wear of the spring on its seat and rips up your valve guides and seats.

    Look at the stem bouncing around like a toothpick. Note that this is a all out race motor spinning revving up to 8400, it is a pushrod motor.



    Here is another video of slow motion rockers. These rockers are shaft mount, for those of you that know; shaft mount rockers are the stiffest setup and are used on race motors. The rockers are doing their job, but look at those spring harmonics.

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  2. #2
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    These springs look like Jello. I can understand why valvetrain development is so important after this.

    Why was the valvespring rotating if this was a race motor though? Shouldn't the valvetrain have already been addressed?

    The vids make me apprehensive about revving the motor higher.

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    ive seen the second video before, but the first one is interesting. what force exactly is making the spring spin? the arm is pushing up and down, so is it the spring itself? when compressed, does the force originate then? ive seen the rocking side to side of the spring's structure but i havnt seen the valvespring rotation you talk about until the video. what are the actual physics going on if anyone can answer?
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    Very cool footage!

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    That's sick how they showed us that

  6. #6
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    Click here to enlarge Originally Posted by oddjob2021 Click here to enlarge
    ive seen the second video before, but the first one is interesting. what force exactly is making the spring spin? the arm is pushing up and down, so is it the spring itself? when compressed, does the force originate then? ive seen the rocking side to side of the spring's structure but i havnt seen the valvespring rotation you talk about until the video. what are the actual physics going on if anyone can answer?
    Good question. I thought about the force vectors and couldn't put my finger on what was causing the rotation.

    The only thing I can think of is the valve stem bouncing which is lifting one end of the spring and then the other, like a pendulum which may induce some rotation. Other than that I have no idea and I am genuinely curious about this too.
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