Question About Roller Rockers

Discussion in 'Fox 5.0 Mustang Tech' started by gnx547, Sep 25, 2013.

  1. I have stud mount Crane 1.7 roller rockers and I adjusted the push rods to zero lash. I used a half turn on the nut and the I tightened down the poly lock. There is very slight movement on the rockers, should there be any movement on rockers? Or no movement at all?
  2. What do you mean by "slight movement"? Are you meaning movement in the sense that it rocks back and forth between the valve and the push rod, or do you mean lateral movement?

    You shouldn't have any rocking back and forth between the valve stem and the pushrod. If you do, then you haven't tightened to zero lash.

    Here's a simple reference chart for the Ford Racking rocker arms. There are examples here for both stud mounted and pedestal mounted versions....
    #2 Gearbanger 101, Sep 26, 2013
    Last edited: Sep 26, 2013
    5point0stang88 likes this.
  3. Yes, lateral movement of the rocker. In the pic, where my 2 fingers are at, there is very little side to side movement of the rocker. Both nuts are tight. Is it normal to have very little play? Or should there be no side to side movement at all?

  4. If either end of the rocker (the roller, or the pushrod cup) is breaking contact with either the valve stem, or the pushrod, then the rocker arms are either adjusted incorrectly, or you need longer pushrods.

    If you're getting up and down movement to the point that the arm breaks contact with either one of these two points, then you're not at zero lash. At zero lash you should have absolutely no up and down movement between the pushrod cup and the pushrod. At zero lash you should be able to spin the pushrod between your finger, with the slightest resistance, but not enough that it rattles up and down.

    Maybe you should take a video clip of the issue to give us a better idea of the problem? My thoughts are that you might be in need of longer pushrods? Did these rods come in a kit with the heads, or the rocker arms?
  5. I think some lateral (side to side) movement is expected using guide plates. A guide plate by design isn't the greatest way to keep a rocker centered. As long as the roller tip isn't leaving the valve.

    The rocker should also be tight enough to not have and forward back play "Up down movement" but you should still be able to turn the valve stem by hand. This is assuming you are using Hydraulic Lifters.
  6. What may seem like an obvious question at this point. Did you check for proper pushrod length or simply reinstall the stock length pushrods. What head gasket are you using.
  7. The pushrods, rockers, heads were all on the engine when I bought the car. I had a bad bearing in the motor so, I replaced it with a Explorer shortbock. I'm using the Felpro 9333PT head gasket. I did not check for proper pushrod length. I looked at the roller tip and it sits in the middle of the valve. If I got longer pushrods, I think the rocker tip will be off the valve. The rocker nut is tight and there is no up and down movement.
  8. edited your post after I replied to you stating that you were getting up and down movement, not side to side movement?!?

    A little lateral movement (a couple of millimeters in either direction) is normal. The roller tip will have a little side to side play, as will the pushrod. They're designed to float around a little. Just as long as you're not getting any up and down movement.

    When you crank the rocker down, you should get between .020-.030 (with OEM lifters) depression on the lifter. This is called lifter pre-load. It's normal and required if you want it to function properly and stay quiet.

    A little preload is a good thing, but you don't want to crank it down so much that it starts to open the valve. This is going to hurt your cause, because not allowing the valve to close all of the way is going to bleed off some compression. The symptoms are a slight drop in power and rough idle.

    A diagram to illustrate what I mean....

  9. Yes, I'm getting side to side movement. So I know now that it is normal for the rocker to that. Thanks for the diagram