Reason I'm asking, is I've been chasing some valve train noise and I've been down the whole pushrod/ preload road. I'm running a .614" lift cam with 7.425's with .075 preload (checked many times.) PRC 5.3's with dual springs.

At idle the valve train is quiet other than a little bit of sewing machine noise, but when I rev the car up to about 15-2000, there is an intermitent clatter/ rattle mostly from one-two cylinders on the passanger side. When you rev the car up, or at higher RPM's the noise goes away? My car runs 55 psi oil pressure at idle and 70 at WOT -while hot.

So basically when going thru the gears while driving, I hear the clatter in every gear, but if I give it more gas or get on it, it goes away. It will clatter some while downshifting too. If I'm crusing in 4th gear around three grand the noise is almost completetly gone.. Crusing in neighborhoods in 2nd gear at 1500-2000 is the worst! Was running 5w-30, switched to 10w40, but didnt seem to help at all..

Anyway, pulled out all my lifters today expecting to find a collapsed lifter and to my surprise they looked good and were all pumped up! I've got new LS7's ready to go in, but I'm wondering now if the old lifters were the problem? Can there be such a problem as a weak lifter that pumps up, but gets loose/noisy at certain RPM's and then gets quieter under throttle when the oil pressure increases? Anybody experience anything close to this? Thanks Jason

 

Are we talking about original LS1 lifters? If so, then you might as well put the LS7's in, and run them, they are the replacement lifters for the LS1..I had some noises out of my originals as well of alot of guys on here..there is a reason that LS7's are now the standard replacement..

 

Yep, original LS1's.. Motor supposedly only had 14,000 miles.. It was a '04 C5stolen recovery and it sat for probably 4 years.. They looked fine, but you never know what is going on inside those lifters! Another thing i noticed was I could spin most all the pushrods with my finger tips after torqued? No lift, I could just spin them.. Is that a sign of a weak lifter? I've read a couple threads that said that was a bad thing?

Now with the olds LS1 lifters out and bled, I can easily push the plunger in and out. The new LS7 had a bath in mineral spirits and soaked in oil for a couple hours, but I was not able to push the plunger in at all, and I'm guessing they are not pumped yet? They seem more stout right out of the box..

 

Yep, as a rule of thumb, just let them sit in good oil overnite, not sure about the mineral spirits thing..Good luck with everything!