[don71]

The factory olds valvetrain is non adjustable. It is a 0 lash system. You only need to worry if you are using an adjustable after market rockers.

The hydraulic lifters used in oldsmobiles have about .050 preload built into them. They are designed to take up a little slack. You want your preload somewhere in the middle. You don't want the plunger in the lifter to bottom out or stack up to full travel or bind on the retainer.

As long as the pushrods are the right length you are ok. IF you had the heads milled and a valve job done it could be possible to have push rods too long. But using the newer thicker head gaskets that we have today, it will make up for some that material taken away in milling the head.

When you have everything installed the push rod should spin, but not move up or down. That is 0 preload.