TurboNasty.. How are the lifters making the sewing machine noise? Is it tie-bar interference or week lifter inner spring. Also does the sewing machine noise give you any false knock?
Missed this question.....I have no false knock and have taken the car to 6000 rpm a few times. My take on it is the bar making some noise is its joined to the lifters via each pair of said lifters...2 per cyl.
So as the lifters do their jobs as a follower to the cam lobe the bar is going to be "See Sawing" if you will and the bar ends arent on a high tech pivot point and will make a sound as it does its movement.
To further explain where noise is coming from with a roller cam or valvetrain in general ......add to that rocker movement, spring psi's affect on all parts of valve train movement. Springs affect is deflection/movement of various valvetrain components as the lobe lifts and falls against valve spring psi.
In the video we arent talking a sewing machine...clearly its more than that.
My first thing would be to verify oil psi at idle and then lube to the top end both banks.
Check the rocker shaft hold down bolts, the rockers themselves...thats the pivots, a darn good visual, etc (also make sure your adjustment fastener isnt blocking internal lube through the rocker assembly...to deep or too shallow will block the oil flow).
Preload or Lash on lifters,
check lift to see if you have a bad lobe.
Then pull intake and check lifters.
Just a quick jist of some starter areas...Good luck and let us know.
