paulandrew1417

So i just had my heads ported, polished revalved and they installed Yella Terra
adjustable roller rocker arms with a hydraulic roller cam.
How Do I Adjust Valve lash?

Gadgetized

iTrader: (9)

You will first need to determine the wipe pattern where the rocker rolls on the tip of the valve stem. The wipe pattern is determined by the height of the fulcrum on the rocker. I take a sharpie magic marker, and color the tip of the valve stem. Install a pushrod, and rocker. Turn the engine over so that the valve fully opens and closes. Now look at the wipe pattern. You want the pattern to fall directly in the center of the tip. If it does not fall directly in the center, move the fulcrum of the rocker up/down accordingly to let it wipe perfectly. It may take several tries to get it where you want it. Once you find the proper spot, that is the proper height that the rocker is to be installed.

Now you need to determine the proper pushrod length. Find what your rocker manufacturer suggests for preload, or how many "flats" (the 6 flat areas on the nut) past zero lash the preload should be set at. This is the amount the plunger on the lifter is pushed down, and is before the valve begins to open. The easiest way to do this is from where the rocker is installed properly. Back the rocker nut off while counting the "flats" on the nut until you get zero preload. If you have too many flats, you need to deduct this from the needed pushrod length, and if you have too few, you need to add that length to the needed pushrod.

If you have an adjustable pushrod length checker, the last part is easier. Just lengthen or shorten the adjustable pushrod until you get the proper amount of flats you are looking for, and place your order.

Hope this helps.