Ok I have had some guy try to tell me when setting hydrulic valves you just tighten them right up? is this true or do I have to cold set them then hot aswell?? Basically what is the right way?

Thanks

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Hydraulic lifters are self-adjusting; you don't want to tighten the nut all the way down, or you'll bottom out the lifter's plunger, and you'll lose the self-adjustability.

First, you tighten the rocker nuts to get "zero lash". As you tighten the nuts, jiggle the pushrod up & down against the rocker arm. When the pushrod loses all "up & down" movement, that's zero lash. Usually you turn the nut an additional 90 degrees. Also, you need to make sure certain valves are open/closed (TDC of certain pistons), and only tighten certain rocker arms. The procedure should be in your car's shop manual...

Zero lash results in the lifter's plunger being at almost the "top". By turning the nut an additional 90 degrees, you push the hydraulic lifter's plunger in a bit- and that's what gives the lifter it's ability to self-adjust. (Thanks to Vader for explaining this to me a while ago!)

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-Tom P (Hot rodded 1986 Firebird 2.8l)

 

Please correct me if I'm wrong, which I'm sure you will.

If you are using the stock rocker arms (stamped ones), and using the stock studs (press fit), you can just tighten the rocker ball down all the way to the torque spec that GM used, right? That is what every repair manual I've ever read says in it. If you don't do that, then what's gonna keep the nut from loosening itself?

What you are talking about is rockers that have a roller fulcrum. The ones that have the set screw on top of the bolt, right? I've used those before.

I've set many solid cams (which of course you can't used stamped rocker arms for) and have experience with them, but any engine I've modded so far has been solid cam. I've never delt with hyd. cams yet.

So really correct me if I'm wrong so I know what not to do.

AJ

 

Chevy's are almost unique these days with adjustable rocker arms, so no, what you are saying is not true.

The later BBC's have gone to non-adjustables, but every SBC from 1955 through our years used a lock nut on a stud to adjust and maintain the rocker setting.

Press-in vs. screw-in studs only relates to how the stud is installed in the head. It has nothing to do with adjustment method.

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