What in the valve lash just happened here?

[Tinman]

Puzzling issue I had with valve lash I discovered last night. A few weeks ago I decided I wanted to change the Ex. last to . 020 to see if it would help spool a little. Also re-torqued head studs one last time. So when I when to re-lash the valves, #4 intake was "tight' when it was supposed to be loss and in the adjust position. I took off the rocker re-seated everything and adjusted. Nothing looked out of place. (One caveat, I had difficultly getting that particular head stud washer off (to re-lube it) so I pulled the push rod. When I re-inserted it, it fell past the tappet. I pulled it back out and re-positioned and it all felt fine. )



I readjusted the other valves, no issues. I rotated the engine over twice by hand then rechecked #4 lash at it was good. Ran the engine a couple hundred miles and re-checked it last night. #4 was way out, I mean greater that . 020. I figure something just wasn't seated correctly and running it settled everything out. But this was weird. I've done the valve a few times and never has a single issue. Just wondering what I did wrong and if anything is amiss.

 

[cerberusiam]

I wonder if you have a seat moving.

 

[JGheen]

I wonder if you have a seat moving.

I was gonna suggest the same thing but I have read that is more common in '03-04. 5' trucks..... being you have an '06 I hope that is not the case cuz I have one too... .

 

[cerberusiam]

I have read that is more common in '03-04. 5' trucks... ...

Common goe sout the window when you heavily modifiy the engines, like the OP had done. Its a pressed in seat and if it hasn't been done to tighter specs and staked correctly anything is possible.



Reset and drive it again to see if it was just a minor glitch in the pushrod install is next up. If the lash keeps changing and everything else is eliminated... ... .

 

[Tinman]

It is a fairly modded engine, but really hasn't been run that hard at all. It has never seen egts over 1250 and rarely gets over 3K rpm. I doubt it's ever been over 450HP. Off course a few stockers have had this issue. Given the fact it was "tight" after I installed the rocker, I think it is just settling in to where it's supposed to be. I don't know why. I'll re-check in a few hundred miles.

 

[SRadke]

Typically it's the exhaust seats that move and if they drop the lash will get loose, not tight. Reset it and check again in a hundered or so miles. I bet you just missed something the first time.



-Scott