Incorrect geometry and wrong pushrod length by itself will not cause any noise.
The primary benefit of correct geometry is to achieve maximum lift from the cam.
A secondary benefit is reduced friction and valve stem wear.
Maximum lift at the valve occurs when (1) the valve stem and (2) a line between the rocker pivot and the valve stem tip are at 90 deg. That should occur at mid lift. Cam base circle and max lift will be on either side of that 90 deg.
None of that will cause noise unless the geometry is way off and something is hitting something else. The noise would not come from the geometry problem itself.
Don't be so quick to ignore an exhaust leak. I hear suggestions of a stethoscope, but I don't hear follow-up on that.
Either a cheap stethoscope or a 2-3 foot long wood dowel.
Another thing you have been ask and not answered is if the noise is from one valve or several.
If the rocker geometry is off on one rocker, it will be off on all twelve, unless you have some extreme dual profile cam with high lift.
Last edited by RichardJ; 11/15/10 04:59 PM.
