wht01ws6ta

iTrader: (45)

I was putting on adjustable Yella Terra rockers and got to the the last valve spring and there was an abnormal amount of slack between the rocker and the valve stem. I found I could adjust it down to zero lash, but it took many more turns than all the other rockers. Then I noticed that when I pushed down on the lifter that it was just solid and was not springy like all the others.

Shouldn't lifters have spring to them regardless of whether they are "pumped up" with oil? Does this indicate a failed lifter???

supergt99

iTrader: (1)

The way your describing it, sounds like you weren't on the heel of the cam. How many more turns did it take after zero lash? How many turns for the other ones? We're there any problems before you swapped rockers?

wht01ws6ta

iTrader: (45)

It was definitely on the heel or base circle of the cam. I've spun it over multiple times to try again. I didn't count the turns but probably around 4 turns on the YT adjustment screw, the other ones were about 1 or less until zero lash.

wht01ws6ta

iTrader: (45)

I should add that I just bought this engine. It is a LS2 402 stroker engine that was disassembled, cleaned up, and reassembled. The lifters were reused by the engine builder, no issues reported there, not sure it the lifters were checked in any way before being put back in.

wht01ws6ta

iTrader: (45)

Any ideas? The pushrods and valves still go up and down but the pushrod is lower than the others and is not springy, it's solid-feeling.

Italianjoe1

Sounds like a collapsed lifter, remove it and check it against another one?

vettenuts

iTrader: (4)

I would count the turns and then use the thread pitch to determine if you are bottoming the plunger. For example, ifyou have three turns with a 3/8-24 thread than this is 0.125" of travel and close to the total plunger travel.

Can you look in and see if the plunger is up at the snap ring with no pushrod in place?

wht01ws6ta

iTrader: (45)

I looked in there with the pushrod out and not sure if the plunger is up at the top or not- it does look different than the one next to it. The YT threads are 3/8 24 like you said and I can count the exact turns and subtract the amount of turns that the other normal adjustment screws have. Should be able to do that this evening. If the plunger is bottomed out, what does that mean? Can it pump back up? I can close the gap with the adjustment screw so it is like the others (although it would be locked in place then and couldn't pump back up once it's run), but what would be the result if it was run like that? Thanks for your help!

vettenuts

iTrader: (4)

If its almost back together, I personally would leave that rocker adjusted the same turns as the others and not run all the way down. Then run the motor up to temp. Hopefully the lifter pumps up. Then pull the valve cover and re-adjust. Worst case it doesn't work and you need to pull the head again. If it works, then hopefully the lifter will be OK.

Alvin@PCMofNC

It sounds like you may have bled it down. It will take oil pressure to pump it back up. You can take new lifters out of the box and compress them a bit. Take some out of a engine that has ran and they are hard as a rock.

wht01ws6ta

iTrader: (45)

It is almost back together and I didn't want to pull a head if I don't have to but of course don't want to damage my engine.

I'm guessing it will just be super noisey with all the space between the rocker and the valve stem until if/when it pumps back up?

So if I run it down until the rocker touches the valve for zero lash or a little tighter, do you think that the lifter will be able to pump back up? If it does pump back up and expand back out, then I guess it would be the same as the pushrods being too long, right?

What risk am I running with no lifter spring flex? It almost seems like a solid lifter. Is this much harder on the cam and the rockers?

wht01ws6ta

iTrader: (45)

Thanks for the info. But are the new lifters and the ones that are hard the same length? Are the lifter cups in the same place? Because the one I am dealing with is hard, but it's also shorter (for whatever reason) so that the pushrod goes in farther.

wht01ws6ta

iTrader: (45)

All right, I went with my better judgment and pulled the head off and pulled out the guilty lifter.

When I dissasembled it I found that the spring was smashed and the bottom end was hooked onto itself so that it was shorter than the others.

I unhooked it and stretched it out to the correct length but when I reassembled it, the plunger did not slide down easy, but ground on the way down, and is still stuck down to the bottom just like before. So, this lifter did indeed fail and a new one is going in.

The photo shows the smashed LS7 spring on bottom, a normal LS7 spring in the middle, and then a LS1 lifter spring on the top. The LS7 springs are longer than the LS1 springs, but the LS1 springs are thicker and beefier, which surprised me.