Quick question on adjusting hydraulic lifters.
Thread Starter
Melting Slicks
Joined: Sep 2004
Posts: 2,412
Likes: 3
Quick question on adjusting hydraulic lifters.
Just got my stud girdles in the mail, finally, so I'm putting on the longer poly locks. I've only done this once before, and that was when the engine was on a stand in the garage, never been run before.
Here's my question: I adjust all the lifters to zero lash with my fingers when the lifter is on the cam base circle. And then I do a half turn of preload. But some lifters have more resistance to the preload than others. Some I can do a half turn with my fingers whereas others I have to use a bit of force with my ratchet. Is this normal?
I'm thinking that the lifters that had lift over night bled off. And the ones with no lift, are still pumped up, which is why they're harder to turn after zero lash. Am I right?
Thanks in advance gurus.
Here's my question: I adjust all the lifters to zero lash with my fingers when the lifter is on the cam base circle. And then I do a half turn of preload. But some lifters have more resistance to the preload than others. Some I can do a half turn with my fingers whereas others I have to use a bit of force with my ratchet. Is this normal?
I'm thinking that the lifters that had lift over night bled off. And the ones with no lift, are still pumped up, which is why they're harder to turn after zero lash. Am I right?
Thanks in advance gurus.
Safety Car
Joined: Oct 2004
Posts: 3,926
Likes: 739
From: Youngstown Ohio
I'm no guru, but yes, lifters do bleed off enough to give you a false feeling for adjustment. Once you make your initial adjustment for zero lash, STOP, or you'll just collapse the lifter if you continue. Adjust slowly and you'll get the "feel" when you're going too far. 
Drifting
Joined: Dec 2004
Posts: 1,345
Likes: 3
With hydraulics you need the engine running to make the adjustment. The small springs in the lifters may not pop the lifters to the far end of their travel after the valve springs have compressed them.
Even with oil pressure expanding the lifters, it takes a little time to get them fully entended, from there, you tighten until they stop clicking (0 lash) and then tighten, GM spec is one turn tighter which puts the lifter in the middle of its travel, I use 3/4 turn, and some use 1/2 turn or less. Using less just means you may get noisy rockers sooner - but there is no risk of the serious damage (burnt valves) that can occur from too tight a valve setting (that keeps the valves from seating).
If you don't want to run the engine when doing your valve adjustments you need solids and then set them to a clearance.
Even with oil pressure expanding the lifters, it takes a little time to get them fully entended, from there, you tighten until they stop clicking (0 lash) and then tighten, GM spec is one turn tighter which puts the lifter in the middle of its travel, I use 3/4 turn, and some use 1/2 turn or less. Using less just means you may get noisy rockers sooner - but there is no risk of the serious damage (burnt valves) that can occur from too tight a valve setting (that keeps the valves from seating).
If you don't want to run the engine when doing your valve adjustments you need solids and then set them to a clearance.
Burning Brakes
Joined: Feb 2004
Posts: 958
Likes: 1
From: In the Beautiful Shenandoah Valley of VA
Originally Posted by StickShiftCorvette
With hydraulics you need the engine running to make the adjustment. The small springs in the lifters may not pop the lifters to the far end of their travel after the valve springs have compressed them.
If you don't want to run the engine when doing your valve adjustments you need solids and then set them to a clearance.
If you don't want to run the engine when doing your valve adjustments you need solids and then set them to a clearance.
Steve
