Hydraulic lifter stuck?

[omgRWDgoodness!]

In a seemingly never-ending quest to figure out why my RB25 isn't starting and having little/no compression after a head gasket job (among other things), I have found that some of my valve lifters being stuck could be the culprit. So, I have been attempting to rebuild them following this write-up:

TwinTurbo.NET: Nissan 300ZX forum - Lifter Rebuild 101: (http://www.twinturbo.net/nissan/300zx/forums/technical/view/917346/Lifter-Rebuild-101.html)

The thing I want to know is whether or not the little piston is supposed to have any vertical movement inside the bucket, because as far as I'm aware it should be able to compress 1-2mm with light to moderate applied pressure. After performing this rebuild on two lifters, they are solid and will not budge a ***thair even when pressing hard. I'm having a brain fart here, are they supposed to be solid like this or actually be able to compress slightly when you squeeze or press down on them?

http://i49.tinypic.com/izrmte.jpg

http://i49.tinypic.com/333lg8z.jpg

[Turtle]

They're supposed to be strong enough to not be pushed back in from combustion chamber pressures. Haven't really got a clue though but, I say they should be good.

[jr_ss]

I would imagine that they should be pretty damn stiff. If it works anything like SR lifters then you should be fine. Break out the FSM and find out?

[omgRWDgoodness!]

The only bit I have found about them in the FSM is this:

http://i48.tinypic.com/fd6kaw.jpg

So I guess "no more than 1mm" means they're supposed to be solid, but then wouldn't that be causing the valves to be slightly open (therefore the engine having little/no compression)? I thought they were considered 'hydraulic' lifters because the cylinder is actually meant to compress a little in order to act as a sort of cushion for the valve when being sent down by the camshaft lobe.

[jr_ss]

So I guess "no more than 1mm" means they're supposed to be solid, but then wouldn't that be causing the valves to be slightly open (therefore the engine having little/no compression)? I thought they were considered 'hydraulic' lifters because the cylinder is actually meant to compress a little in order to act as a sort of cushion for the valve when being sent down by the camshaft lobe.

My interpretation of that, is yes, they are suppose to be solid, meaning no squishy squishy with your fingers.

Just because the cam is riding on the lifter, doesn't mean it's compressing the springs and pushing the valve into the combustion chamber. The base circle of your cam is the round portion without any slope or ramp up. This rides on the lifter and gradually compresses the spring as the cam rotates on to the ramp up and eventually lobe of the cam.

The term hydraulic simply means that it is a zero tolerance lifter. It is filled with oil intermittenly(when the valve is closed) via a small oil hole. There are mechanical lifters as well, where you have to adjust valve lash every X thousands of miles.

SR lifters are exactly the same, bleed the air out and you shouldn't be able to compress them. Hope this helps.