Pushrod Geometry
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Pushrod Geometry

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    Senior Member wagspe208's Avatar
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    Default Pushrod Geometry

    SF is mid lift 90* rocker pivot/ valve stem. This does not necessarily put rocker tip on the center of the valve.

    I was taught the center of tip, smallest pattern years ago.

    I see the validity of both methods.
    Discuss away.
    Wags

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    Senior Member johnf's Avatar
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    Quote Originally Posted by wagspe208 View Post
    SF is mid lift 90* rocker pivot/ valve stem.(This does not necessarily put rocker tip on the center of the valve.)????

    I was taught the center of tip, smallest pattern years ago.

    I see the validity of both methods.
    Discuss away.
    Wags
    Is the valve open or closed when not at center of stem?

  4. #3
    steelcomp was here
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    Quote Originally Posted by wagspe208 View Post
    SF is mid lift 90* rocker pivot/ valve stem. This does not necessarily put rocker tip on the center of the valve.

    I was taught the center of tip, smallest pattern years ago.

    I see the validity of both methods.
    Discuss away.
    Wags
    Smallest pattern, narrowest sweep is the goal. The 90* mid lift method will give you that result. They are one and the same. Location of the pattern is secondary IMO.
    If God is your co-pilot, change seats!
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    Senior Member bp298's Avatar
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    "pushrod geometry". straight is good. bent is bad...

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    Senior Member Hass828's Avatar
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    Quote Originally Posted by bp298 View Post
    "pushrod geometry". straight is good. bent is bad...
    Lmao!
    "if we keep doing it the same way we always do..we will always get the same results"
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    Senior Member wagspe208's Avatar
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    Center of valve would seem to induce the least outside force other than to cl of valve stem. Less side loads.
    I realize this is splitting hairs. I have not had failures. I like to learn.
    The T&D exh were set up and a little past valve c/l.
    My Jesels were set up to cl.
    I totally agree with small pattern.
    Wags

  9. #7
    steelcomp was here
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    Quote Originally Posted by wagspe208 View Post
    Center of valve would seem to induce the least outside force other than to cl of valve stem. Less side loads.
    I realize this is splitting hairs. I have not had failures. I like to learn.
    The T&D exh were set up and a little past valve c/l.
    My Jesels were set up to cl.
    I totally agree with small pattern.
    Wags
    Think of it this way; you're trying to convert radial motion to linear motion. With the rocker arm you have both vertical and horizontal movement which is evident by the sweep. The less horizontal movement you can have, the more vertical movement there will be. It's the horizontal movement that side loads the valve. Minimize the horizontal movement and you will minimize side loading. If the vertical movement is as linear as possible, then it really doesn't matter if it's a little off center. The 90* geometry gives you the least amount of horizontal movement and the most linear vertical movement in relation to the valve.
    T&D designs their rockers using the 90* philosophy. Jesel does not, and this becomes important when looking at the push rod side of the rocker. If you try to set up a Jesel rocker using the 90* method, you can get in trouble on the push rod side. The pushrod side of the rocker, IMO, should follow the same 90* geometry as the valve side. The imaginary line through the center of the trunnion and center of the push rod ball should be 90* to the push rod at mid lift. Unfortunately, to have this perfect you'd have to have a special set of rockers for every given lift and that's just not practical. That's why I tend to focus more on the valve side of the rocker than the push rod side.
    Last edited by scott foxwell; 07-30-2015 at 09:15 AM.
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    Senior Member wagspe208's Avatar
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    Ah, I'm hip to what you are saying blood. I get the theory behind that now. Makes sense.
    Now, I wonder how close to your theory, (which I was aware of), I was all of these years.
    Wags

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    Senior Member PE 340's Avatar
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    Quote Originally Posted by bp298 View Post
    "pushrod geometry". straight is good. bent is bad...
    How did Ya figure that one out ???

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    Village Idiot fc-Pilot's Avatar
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    Quote Originally Posted by bp298 View Post
    "pushrod geometry". straight is good. bent is bad...
    In our PC world you can't say that. The proper statement is "Straight is a choice, bent is a choice. Both are good choices, but one is best for me." LOL

    Paul

    Sorry, I could not help myself.

  13. #11
    Senior Member bp298's Avatar
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    Quote Originally Posted by PE 340 View Post
    How did Ya figure that one out ???
    i think I learned that 50 or 60 years ago. but I can't remember. still seemed appropriate for the thread title...

    Quote Originally Posted by fc-Pilot View Post
    In our PC world you can't say that. The proper statement is "Straight is a choice, bent is a choice. Both are good choices, but one is best for me." LOL

    Paul

    Sorry, I could not help myself.
    no prob. not sure one is a choice and not sure one is a good choice. of course, in filler world you just gotta do what you gotta do

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