so the rockers on my lt1 seemed like they were making a little noise, so i decided to try setting the lash on them. it has 1.6 ratio full roller rockers. i have never set lash on an engine before and after looking over the various methods setting it with the engine running looked like the easiest way. i did the drivers side first, loosening each one till it clacked and then tightening it down, till it quieted down then about an 8th turn. i did the driver side and then did the passenger side. after doing the passenger side i waited about an hour then started it up, it sounded good and the rockers seemed quiet. then i took it for a little spin down the road, about a 1/4 of a mile down the road the engine started making a loud tapping sound like a lifter was loose, and the exhaust note changed. so i turned around and went home, i popped the hood and it seemed to be coming from under the driver side valve cover so i pulled it off and tried backing off the very first rocker but it didnt get louder so i started tightening it but that didnt seem to quiet it either. i then cut the motor off before i made things worse. i let it cool some and then came back out. i noticed that the pushrod could move like an 8th of an inch up and down on the very 1st rocker, this seemed like a major problem but tightening it down a little didnt seem to help. so basically what happened, how might i fix it, and where did i go wrong? i know id never done it but it didnt seem hard? hope i didnt screw things up royally

 

Of all the engines I've done, I've never had it go like that. I'll think on it tonight.

 

yeah ive been reading and reading but can seem to find anything quite like this.

 

Maybe the lifter bled down between the time you left and came back to check the rockers. That or possibly a collapsed lifter. Its been a long time but I've never experienced anything like you described. Try setting the lash the long way with the engine off.

 

pulled a few of the rocker arms from that side to look, there is some gouging of the metal on the arm where it sits on the rocker stud, i pulled rocker arms from a few other cyls to see and they had the same thing going on, i attached a pic. its the exhaust valve on cyl#1 that seems to be the main problem, i went to adjust it with the engine off using method 3 on shoeboxes site and i may be doing it wrong but it still had significant up and down play even with the nut cranked all the way down.

 

i had an engine do this very same thing, i'm not sure how the studs on lt1 engines are but it was the rocker stud actually pulling out of my head. and i didn't have a very larg cam in. just something to look at. just put a straigh edge along the studs and see if they are all flat

 

Since those aren't self-aligning rockers, I assume you have push rod guide plates.

1/8 turn down isn't enough. But, it shouldn't cause side motion. Not sure if it would damage the lifter. Maybe Atilla will be able to come up with something.

 

yes sir have guide plates, the pushrod looks good just a little wear at the guide plate area. ill check the stud i looked at it today and it seemed solid but i didnt really know what i was looking for

 

well oddly enough i went out yesterday and it would tighten down just fine. what kind of preload is good for roller rockers?

 

I had always used the 1/4 turn method but I will say alot of full roller rockers are known to make more noise... plus the locking screw has to be tight!

 

got it all done today. used 1/4 turn of preload and got the poly locks as tight as i could with an allen key