Rocker adjustment

[Supercharged111]

So a few weeks ago I replaced my head gaskets and I at the time I ended up over tightening the rockers, so I went back in and reset zero lash from scratch plus a a half turn. After that there was a slight rattling so I went back in, gave them all an additional quarter turn and now the engine feels a bit rough through the entire rpm range.

Could a quarter turn really take me from a pinch loose to past acceptable preload?

No. 1 full turn is stock spec. My LT1 is at a full turn and makes around 300whp with nothing more than not stock intake and manifold back exhaust.

 

[Schurkey]

I went back in and reset zero lash from scratch plus a a half turn. After that there was a slight rattling so I went back in, gave them all an additional quarter turn and now the engine feels a bit rough through the entire rpm range.

Could a quarter turn really take me from a pinch loose to past acceptable preload?

YES, depending on the lifters used, and how accurately "zero lash" was located.

I've seen OEM "stock" ordinary lifters that had more than a quarter-inch of plunger travel.

I've seen "High Performance" lifters that had less than ten thousandths of an inch of plunger travel.

Now you guys are finding out why I like to do this with the intake manifold OFF, so I can SEE the plunger travel, and verify that I'm at "zero lash". Zero Lash is EVERYTHING. Once all the rocker nuts are set to TRUE "zero lash", a monkey or a third-grader could turn all the rocker nuts the additional 1/2, 3/4, or full turn as desired.

 

[Hipster]

So a few weeks ago I replaced my head gaskets and I at the time I ended up over tightening the rockers, so I went back in and reset zero lash from scratch plus a a half turn. After that there was a slight rattling so I went back in, gave them all an additional quarter turn and now the engine feels a bit rough through the entire rpm range.

Could a quarter turn really take me from a pinch loose to past acceptable preload?

Yes. I have come across factory replacement type lifters where anything past 1/2 held valves open. In such cases I set at zero lash plus a little more then 1/4 turn. There are different types lifters out there. performance lifters usually come with paperwork so the parts you have are more important then what a manual says is in this situation.

Your looking for a sweet spot. Not zero lash but less then bottomed out holding valves open. All valves throughout the engine should be set the same way. Most stock type lifters have a window of say .030-.060 that is acceptable.

 

[Jesse_Wenting]

Now you guys are finding out why I like to do this with the intake manifold OFF

Admittedly I should've gone that route when I was replacing all the gaskets and seals, but I had read this forum after over-tightening my rockers (ironically because I was rotating them lol) and thought I would get by fine by holding the arms off the rods and feeling the tolerances closing.

There was no vertical movement in of the rods before I did my initial half turn, so is the sound I was hearing a normal thing? My dad's 96 had the same kind of sound and I always thought it was a loose rocker arm

 

[CKVortec]

So a few weeks ago I replaced my head gaskets and I at the time I ended up over tightening the rockers, so I went back in and reset zero lash from scratch plus a a half turn. After that there was a slight rattling so I went back in, gave them all an additional quarter turn and now the engine feels a bit rough through the entire rpm range.

Could a quarter turn really take me from a pinch loose to past acceptable preload?

Yes... Yes it can.
I just finished my 3rd engine swap (3 trucks) with reman long blocks. the first two had no issues and ran well right out of the box. #3 ran like crap.
After determining that I had a dead miss on cylinder 7 I did a compression test and found none whatsoever.
I did a leakdown test and found that the intake valve was not closing. This engine obviously did not get compression tested after assembly and may well have been a Friday afternoon or Monday morning hangover build.
When I readjusted that valve I found that anything over 1/2 turn from zero lash was opening the valve.
There is very little distance between too loose and too tight.
I ended up readjusting all the valves in the engine to about 3/8 turn.