The amount of preload depends on the lifters used, and somewhat on the philosophy of the person doing the work.
I've seen OEM hydraulic lifters with more than a quarter inch of plunger travel.
I've seen hydraulic lifters with less than .010 of plunger travel; and no damn notice on the box that they were restricted-travel lifters.
Some guys want the lifter plunger near the top of it's travel, so it can't "pump up" at higher RPM.
Some guys want the lifter plunger near the bottom of it's travel, so it can't "leak down".
Some guys follow the service manual procedure for lifter preload; it used to be one full turn but I think that's changed in later years.
Some guys have their own "secret sauce" recipe for preload--1/2 turn from zero lash, 1/4 turn...whatever.
As long as the preload doesn't exceed lifter plunger travel, you're pretty-much "good to go" although it's helpful to verify proper pushrod length. You need "some" preload, but not more than the lifter can accommodate.
I've set lifter preload with the engine running, with the engine cold, and with the engine warm but not running. Doesn't really matter--it's just NOT THAT CRITICAL on stock engines.
If we're talking about stiff valve springs and high-rpm, I'd be inclined to use a longer pushrod if needed, and put the plunger near the bottom of it's travel...but that's me, and not everyone agrees.
The restricted-travel lifters do it all--the lifter is near the top of it's travel so it can't pump up, it's near the bottom of it's travel so it can't leak down. It's one step away from a solid lifter. Which also means it's not capable of long-term "set-and-forget" applications like an OEM lifter.
I've seen OEM hydraulic lifters with more than a quarter inch of plunger travel.
I've seen hydraulic lifters with less than .010 of plunger travel; and no damn notice on the box that they were restricted-travel lifters.
Some guys want the lifter plunger near the top of it's travel, so it can't "pump up" at higher RPM.
Some guys want the lifter plunger near the bottom of it's travel, so it can't "leak down".
Some guys follow the service manual procedure for lifter preload; it used to be one full turn but I think that's changed in later years.
Some guys have their own "secret sauce" recipe for preload--1/2 turn from zero lash, 1/4 turn...whatever.
As long as the preload doesn't exceed lifter plunger travel, you're pretty-much "good to go" although it's helpful to verify proper pushrod length. You need "some" preload, but not more than the lifter can accommodate.
I've set lifter preload with the engine running, with the engine cold, and with the engine warm but not running. Doesn't really matter--it's just NOT THAT CRITICAL on stock engines.
If we're talking about stiff valve springs and high-rpm, I'd be inclined to use a longer pushrod if needed, and put the plunger near the bottom of it's travel...but that's me, and not everyone agrees.
The restricted-travel lifters do it all--the lifter is near the top of it's travel so it can't pump up, it's near the bottom of it's travel so it can't leak down. It's one step away from a solid lifter. Which also means it's not capable of long-term "set-and-forget" applications like an OEM lifter.
