ls7 lifter preload
Finding zero lash is where people have issues, and if anything, they get them too tight, not too loose. Just where you can't move the pushrod up and down, and the rocker doesn't pivot freely or rock side-to-side freely, is zero lash.
With any preload at all, the pushrod won't pop out of the cup.
I run mine at just 1/8 turn past zero, as insurance against pump up due to any possible valvetrain float at 7100 rpm.
Finding zero lash is where people have issues, and if anything, they get them too tight, not too loose. Just where you can't move the pushrod up and down, and the rocker doesn't pivot freely or rock side-to-side freely, is zero lash.
With any preload at all, the pushrod won't pop out of the cup.
I run mine at just 1/8 turn past zero, as insurance against pump up due to any possible valvetrain float at 7100 rpm.
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As already stated, when adjusting valves your best bet is to wiggle the pushrod up/down to find zero lash. Because you are adjusting the pushrod up against the plunger spring in the lifter there will be very little resistance. It is perfectly normal for the adjusting nut to be very easy to turn. Just keep your adjustment past lash consistent with the other valves.
True story, if you have never talked to anyone in person who knows what they are doing and then follow the directions from the manufacture, you would think they would tell you this. They do not.
So go back to 2005, I am doing rockers for the first time in my life. I did the half and half method, noticed the first set of 8 I had done were loose again. So I tightened them again. I did this over and over and over until I couldn't move the pushrod. OOPPSSSSSS!!! Wayyyyy too tight!
So obviously the car wouldn't start and I had no idea why, I figured I had done them right. Lesson learned. ROCKERS SHOULD SHIP WITH DIRECTIONS THAT STATE ADJUST ONCE! Why? Because obviously if a person has never done them before and logically thinks, hey let me check those I had adjusted already, well it does create an issue.Do them only one time, yes when you bring it back around it will seem like they are loose, but they are not.
So I do engine running.
Tighten them all, start the car and let it idle.
Loosen one rocker at a time until it clicks, then tighten till it stops then 1/4 turn past that.
Repeat.
Next a lifter pumps up using the remaining space between the cup/piston assemblies and a step inside the lifter inner body - forced open by a spring. This is what is used up when setting pre-load. So the less preload the more it allows the lifter to pump up once the lifter reaches the top of the cam lobe. Yes the less pre-load adj the more it allows the lifter to pump up - not the other way around. If u want to reduce pump-up then increase the pre load and the shop manuals will tell u to adjust up to 1 full turn - good idea. Thats another concept someone would have to be able to read to comprehend. Anyone can google this but it may take a few re-reads and hours to sort it out.
97 if u do some searching u will find a lot of others having problems with the poly-locks loosening up. The trick is to once u have the preload set is to bump the nut in the tight direction to help lock it down. If your loosing your preload setting then its the polylocks slipping not the lifter.
Also if u still have an old lifter then u should try and depress that cup yourself and u will realize u wont be able to force that cup down yourself. Priming has nothing to do with it. Its the spring inside that lifter that resists the cup and its strong as hell. The preload is determined by the space between the piston and a step inside the lifter body that stops it form moving downward further.
As for getting on the cam base circle i like to use the firing order 1-8-4-3-6-5-7-2 as there are always 2 pistons at TDC at the same time but one is on the compression stroke - with vlvs shut - and the other is in overlap - with both vlvs open. U can see this as u rotate the engine. The pistons go to TDC is pairs: 1&6, 8&5, 4&7, 3&2. Just look for one cyl vlvs to open and the other cyl will have both cam lobes on the base circle ready to adj.
Adj hyd lifters is critical to engine life and this forum is full of bad mouthing clowns to lazy to even look it up let alone explain it correctly.
Hope this helps more than it hurts,
cardo
GTFOH!
Hope all you want. Once again, it didn't happen
That preload distance is what can hold the vlv open at high rpm - called "pumped up". The village idiot calling others morons cant see that and thats his problem. But the less preload on the lifter the more distance is available under the piston and the more lifter can "pump up" at high rpm. And thats the fact! Right in front of your eyes now. The more preload u add the less the lifter can pump up - thats the fact!
I dont know why that village idiot continues to post his azzbackwards description. Mentally incompetent.

And the other village idiot cant see how the spring is holding the piston up when adjusting the preload but instead babbles on about the retainer clip.
Because he cant figure out how it works either though its right in front of him. I guess hes still waiting for the lifter to bleed down - ho, ho, ho. Still waiting for him to explain how the lifter bleeds down. And how long it takes too - ho, ho, ho.

You're a kindergarten math student trying to do Algebra.
Back to yer books.
97, You were WAY beyond zero lash before you put that 1/4 turn on them, if it resulted in all that carnage.
Stop worrying about the pushrod coming out of the cup. I think you should find somebody local to show you how to do this just this one time; it will make sense after that. very easy to show someone; harder to explain.
Last edited by bowtienut; Apr 25, 2014 at 12:40 PM.










