It's been awhile since I adjust preload in an LS1, but my 98 has a bit too much valve train noise at idle for my taste.

I think I have too little lifter preload (its about 1 turn right now).

I have 7.35" pushrods and no shims. I put in the stock (7.38") pushrods, but when I tightened the rockers down the valve started to move a bit (maybe 1-2mm), and it took around 2 turns, so I think that would be too much preload.

I do have some .030 shims, but if I run a .030 shim with the 7.38" pushrod I'm right back where I started with the 7.35" pushrod.


Any ideas??



Thanks,
Terry

 

I dont know for sure about this, and someone will correct me if I am wrong, but stock ls1 rocker arms torqued to 22 ft lbs will give the proper preload (whatever stock is). So do the marker on the valve stem trick, get the correct pushrod length for proper valvetrain geometry, then when the pushrod length is correct, torque the rocker arms down to spec and everything should be set.

 

Well, you use shims and different length pushrods to adjust preload. The trick is finding the right length pushrods / shim combination to get that preload where it needs to be.

 

What if the Geometry is off? Stock rockers are not adjustable as far as preload goes. You have to torque them down to 22 ft lbs.

Here is a post on this. Note what Predator Z says. He is right.
https://ls1tech.com/forums/showthrea...er+arm+preload

 

Here is a link. http://www.holley.com/HiOctn/TechSer...ECVTTech1.html

Do this and get your goemetry right. Then Torque the rocker arms in the correct sequence and to 22 ft lbs. That is it. Everything should be legit.