She is not sounding healthy

[dassaur]

Does that upgrade part they used fit an L98? Also anyone know if the sump can come off the L98 as easy as that LS3? No I won't be doing it but I thought it was engine out for sump off.

Yes. To both. I just did it on my L77(all these gen 4 wet sump are the same)
It's not as 'easy' to take the sump off as they make it look.
You undo the front 4 sump bolts from on top of engine bay with 10mm spanner (ratcheting is worth it).
Jack up car. Undo bottom of engine mounts. Jack up engine via sump. Chock some wood where the engine mounts are. Then you can do the sump.

 

[lmoengnr]

8mm not etorx

Are you sure?

 

[dassaur]

Are you sure?

View attachment 240668

100%
8mm hex

 

[lmoengnr]

Just wanting to learn more…

I always understood the LS3 hydraulic lifters uses oil to automatically provide zero lash adjustment. The lifter internal bore which contains a piston within the lifter itself would fill up with oil and take up any slack. As such the pushrod pressing on lifter piston and the rocker itself would have zero lash and the engine would be nice and quiet during operation. Seemingly simple but actually a complex device I don’t fully understand.

If the lifter would bleed down due to the engine standing unused for some time, the valve train would clatter away on startup until the lifter piston reservoir filled up with oil and lash was returned to zero. That’s why some engines sound so tappety in the mornings.

If a lifter is faulty, due to some oil crud getting inside or wear because of faulty tolerances or metallurgy or wrong oil viscosity?, it may cause some issue with the lash adjuster mechanism within the lifter itself. The lifter could more easily bleed down and thus noise or pump up which causes other problems.… I think this is what Forg was getting at in that a lifter may be faulty…

Again as I understand it, LS3 lifters provide this hydraulic lash adjustment. So when we talk of lifter preload, I understand it’s to position the lifter internal piston that the pushrod rests on within the middle of some defined position within its possible stroke (within the lifter body itself).. and in this context t a bent pushrod upset this preload which can cause issues itself.

Have I understood the comments correctly and how the LS3 valve train lash & preload works? cause my head hurts now

On most engines, you set lifter preload by adjusting rockers down on a stud, usually 1.5 turns.
LS rockers attach to the head in a fixed position. If everything is factory spec. standard push rods will work.
If the head has been skimmed, block decked, or cam changed, you'll need to check push rod length to get the correct lifter preload.

 

[Skylarking]

On most engines, you set lifter preload by adjusting rockers down on a stud, usually 1.5 turns.
LS rockers attach to the head in a fixed position. If everything is factory spec. standard push rods will work.
If the head has been skimmed, block decked, or cam changed, you'll need to check push rod length to get the correct lifter preload.

Thanks, that’s how I understood the LS3 works; factory spec hardware is just bolt on with some sanity checks.

So just to reconfirm, changing factory specs by skimming the head in essence makes the pushrod seem longer (as the cam base circle to rocker distance gets physically shorter). This seemingly longer pushrod pushes the lifter’s internal piston further down into the lifter bore thus altering (increasing) preload (preload cause the piston within the lifter has a spring pushing it up against the pushrod). I’d guess that skimming the head too much would increase the preload too much, to the point the lifter‘s internal piston will bottom out within the lifter’s bore. I’d guess in such cases they’ll act much like a solid lifter but can still pump up hydraulically which ain’t really great. So the solution is to install physically shorter pushrods to keep that base circle to rocker length the same as in a standard engine and thus the lifter’s internal piston within the desired part of the lifter's bore (preloading the spring the desired amount?)…

Likewise, the flip side where one installs a cam with a smaller base circle. In that case the pushrod seemingly becomes shorter which means the preload is reduced. Reduce the preload too much and the piston will hit the retaining circlip within the lifter which means in extreme cases the push rod won’t even be retained between the lifter and rocker. Solution is a longer pushrod.

So the lifter preload that’s being discussed is the actual preloading of the piston spring within the lifter itself and thus relates to the lister’s internal piston position within the lifter. From what I’ve read, some engine builders prefer more preload (supposedly to reduce oil volume within the lifter thus reducing any compressible air bubbles within the oil) some prefer less less.

The bit I don’t understand is how one measures what the correct pushrod length should be and thus what pushrod length one needs to buy. And I also don't understand what the limits are in preload before problems start to be seen within valve train control and longevity. Guess I don’t really need to know such, just need to know a good engine builder

But without understanding stuff you’d always have to go to a mechanic or engine builder when there are funny noises with the valve train and where is the fun in that

 

[07GTS]

pump up the lifter so its at full extension and use adjustable pushrod to get zero play then add preload amount to that, each lifter will have a load to be within, as well as being loaded within the lifter it's also to take account the expansion of the block and heads, iron block and alloy heads have different preload as expansion is less then all alloy

 

[lmoengnr]

Thanks, that’s how I understood the LS3 works; factory spec hardware is just bolt on with some sanity checks.

So just to reconfirm, changing factory specs by skimming the head in essence makes the pushrod seem longer (as the cam base circle to rocker distance gets physically shorter). This seemingly longer pushrod pushes the lifter’s internal piston further down into the lifter bore thus altering (increasing) preload (preload cause the piston within the lifter has a spring pushing it up against the pushrod). I’d guess that skimming the head too much would increase the preload too much, to the point the lifter‘s internal piston will bottom out within the lifter’s bore. I’d guess in such cases they’ll act much like a solid lifter but can still pump up hydraulically which ain’t really great. So the solution is to install physically shorter pushrods to keep that base circle to rocker length the same as in a standard engine and thus the lifter’s internal piston within the desired part of the lifter's bore (preloading the spring the desired amount?)…

Likewise, the flip side where one installs a cam with a smaller base circle. In that case the pushrod seemingly becomes shorter which means the preload is reduced. Reduce the preload too much and the piston will hit the retaining circlip within the lifter which means in extreme cases the push rod won’t even be retained between the lifter and rocker. Solution is a longer pushrod.

So the lifter preload that’s being discussed is the actual preloading of the piston spring within the lifter itself and thus relates to the lister’s internal piston position within the lifter. From what I’ve read, some engine builders prefer more preload (supposedly to reduce oil volume within the lifter thus reducing any compressible air bubbles within the oil) some prefer less less.

The bit I don’t understand is how one measures what the correct pushrod length should be and thus what pushrod length one needs to buy. And I also don't understand what the limits are in preload before problems start to be seen within valve train control and longevity. Guess I don’t really need to know such, just need to know a good engine builder

But without understanding stuff you’d always have to go to a mechanic or engine builder when there are funny noises with the valve train and where is the fun in that

Correct!
Engine builders(and DIY people) will use an adjustable pushrod to gauge the correct length. @07GTS beat me to it!

 

[dassaur]

The bit I don’t understand is how one measures what the correct pushrod length should be and thus what pushrod length one needs to buy.

This is the best video I've seen on it.

Lifter preload is also specced by the lifter manufacturer. In my recent top end rebuild, Johnson spec. 035+/-. 010 preload.
For example I ended up measuring about 7.3 and a hair pushrod length (tool is accurate to around. 025, 7.325 was measured as too long), then adding preload I went with a 7.35 push rod. If I used gm lifters I would've gone 7.375

The stock gm lifters (often referred to as LS7) don't have a spec. Various sources suggest anywhere from. 05 to. 08

 

[Skylarking]

pump up the lifter so its at full extension and use adjustable pushrod to get zero play then add preload amount to that, each lifter will have a load to be within, as well as being loaded within the lifter it's also to take account the expansion of the block and heads, iron block and alloy heads have different preload as expansion is less then all alloy

I understand using adjustable pushrods you can use to set lash to zero and then measure what length you need. But how does one ensure the lifter is pumped up so the lifter’s internal piston is presumably pushed up within the lifter and against the circlip (so you can then add the lifter manufacturers preload to the measured length)?

And if the lifter is stuffed internally, which could be the cause of an annoying tapping sound, how does one check that?

PS I’ve only played with OHC hydraulic lifters and old style bolt and nut adjustable rockers… not played with LS valve train…

 

[Daniel Souza]

This is the best video I've seen on it.

Lifter preload is also specced by the lifter manufacturer. In my recent top end rebuild, Johnson spec. 035+/-. 010 preload.
For example I ended up measuring about 7.3 and a hair pushrod length (tool is accurate to around. 025, 7.325 was measured as too long), then adding preload I went with a 7.35 push rod. If I used gm lifters I would've gone 7.375

The stock gm lifters (often referred to as LS7) don't have a spec. Various sources suggest anywhere from. 05 to. 08

I was about to post this video.
This channel is very good