Installing and Adjusting Rocker Arms

I learned this technique like many of the others I have come to almost master over the past two years, by trial and error! After reading countless articles and how to books on installing and adjusting rocker arms, I fournd an article in the Mustang 5.0 magazine that help solidify the installation for me.

And come to find out a little common sense was all that was needed after all! Go figure. I will list key parts of the article below along with pictures and some common terms that might not be "common" to everyone.

I hope this article helps those of you who are first timers, because I know how hard it is to do it first hand! And for those of you who may know the terminology, please don't feel affended by my explanations, if more people would have assumed I knew nothing from the beginning, I would have saved countless hours and no telling how much money!

  

 

While a hydraulic lifter valvetrain is designed to have zero lash, there is a specification for lifter preload. Preload causes the pushrod seat in the lifter to move down, between .020" and .060". If preload is non-existent, the valvetrain will be noisy, and the hydraulic pressure against the pushrod seat retaining lock can cause the lock to fail.

Excessive preload isn't good either. If the pushrod seat is compressed too much, the valve opens longer and higher, which decreases cylinder pressure. Preload can change due to a valve job, surfacing the heads or block or even a new cam.

1. To adjust the intake valve on a particular cylinder, first turn the engine over until the exhaust valve on the cylinder just begins to open. Wait a mement for the hydraulic lifter seat to move up toward the retaining lock. Start with twisting the pushrod and turning the adjuster nut until a slight resistance is felt, this is zero lash. Now turn the adjustment nut 1/2 to 1 full turn from that point.

2. Now lock the adjuster. One common error is that people turn the Allen wrench to lock it. The proper way is to hold the Allen wrench and turn the box end wrench. Now turn the engine over as the adjusted intake valve fully opens and begins to close. When it is almost closed, stop. Now the exhaust valve on the same cylinder can be adjusted.

Another method I have also used is getting the cylinder to TDC, which actually equates to both pushrods being at there lowest point. A lot of people don't like this method due to its ability for error. However, if you rotate the crank till the exhaust bottoms out and then a little more, if the intake doesn't open, then you are at TDC.

If the intake side begins to open continue with the rotation until pressure is released from both pushrods, this will be TDC. I think this was the easiest and most time efficient for me, you may like your own way! If you have anything to offer, please feel free to email me!



  
Here is yet another method:

1. Remove the valve covers, and pick a cylinder you are going to set the preload on.

2. Hand rotate the engine in its normal direction of rotation and watch the exhaust valve on that particular cylinder. When the exhaust valve begins to open, stop and adjust that cylinder's intake rocker arm.

3. Back off the intake rocker arm adjuster and remove any tension from the pushrod. Wait a minute or two for that hydraulic lifter to return to a neutral position. The spring inside the lifter will move the pushrod seat up against the retaining lock if you give it time to do so.

4. Now spin the intake pushrod with your fingers while tightening down the rocker arm. When you feel a slight resistance to the turning of the pushrod, you are at "Zero Lash". Turn the adjusting nut down one half to one full turn from that point. Lock the adjuster into position. The intake is now adjusted properly.

5. Continue to hand turn the engine, watching that same intake. It will go to full open and then begin to close. When it is almost closed, stop and adjust the exhaust rocker arm on that particular cylinder. Loosen the exhaust rocker arm and follow the same procedure described before in steps 3 and 4 to adjust this rocker arm.

6. Both valves on this cylinder are now adjusted, and you can move on to your next cylinder and follow the same procedure again.