when adjusting rocker arms what is meant by removing lash? The movement of the push rod up and down and what about side to side? Should you still have the rod moving side to side with drag? Finally what would be the xtra turn after removing lash? (on an l98)

Thanks in advanced!

 

i think not a pro adjust till rocker can't move?? DO NOT OVER TIGHTEN

 

Lash is any play in the valve train between the camshaft and the valve stem. Any side movement of the rocker arm is not a part of the valve lash.

For adjusting hydraulic lifters, first you adjust to "zero lash" with the lifter sitting on the base circle of the cam. To aid in determining when ZERO is reached, I like to move the push rod up and down until it won't move any more and STOP adjusting. Some people prefer to twist or spin the push rod, but if the plunger spring in the lifter isn't very strong, it's easy to go past "zero lash". Preload will have no (zero) lash, but you want the valve train where all the lash is just barely removed, so you can accurately determine the amount of preload. The amount of preload on the hydraulic lifter.

RACE ON!!!

 

For the best method go to www.cranecams.com and follow their instructions. Forget the Service Manual guidelines as they are not as precise. Also, don't crank down on the nut until the push rod is so rigid that it won't move at all. I did that without realizing I had completely collapsed the lifter and damn near ruined my heads.

Start by turning each nut until you feel a slight resistance on the push rod. You can twist the rod between your fingers or move it up and down - depends on what works for you, but if you practice, you will eventually determine what that resistance feels like. For me, once I get close to where I think all the slack is out, I start turning the nut very slowly.

Once the slack is out, follow the Crane method and pick out a set of valves to work on. Turn the engine over by hand until the exhaust valve just begins to open. The cam lobe for the adjacent intake valve is now on it's base circle. Loosen the nut on the intake rocker, wait a few seconds, and retighten again until you feel the resistance on the push rod. You can do it a couple of times so you get a sense of what it feels like, just be sure to wait a little bit after you take all of the slack out of it before tightening it back up. Once you're confident of what it feels like, turn the nut one complete turn from where you first felt the resistance.

To adjust the exhaust valve, turn the engine over until the intake you just adjusted opens and then closes at least halfway. You are now on the base circle for the exhaust valve. Adjust the same way.

Do this for each set of valves. I find it helpful to have the distributor installed and the cap off as I can then use the rotor to give me an idea as to how close a piston is to TDC and what the valves are going to do.