Originally Posted by helrazr3
ok so do i need to change the valve springs too? its not a big race engine with crazy stuff i started this idea because i know roller is an upgrade from stock and i can eliminate the stock rocker arm adjustment from the equation
Actually no you can't eliminate the rocker arm adjustment from the equation, rollers are adjusted just like the sliding shoe by using the rocker nut to set the lash of a solid or travel of a hydraulic. The one thing that tends to be easier is seeing where the contact point is between the rocker's roller and the stem as knowing this is essential to picking the best length push rod.
Push rod length and its effect on where the roller (or sliding shoe for that matter) establishes two things:
- The off center forces introduced into the valve stem that cause it want to bind in the guide, this is a wear issue for guide and stem and an oil seal issue for the stem seal. You see the result of this in the guide wear being an egged shape in the direction of the rocker rather than uniform wear around the guide bore.
- The other is dynamic rocker ratio; the stated rocker ratio is a static dimension from the center of rotation to the push rod cup on one side and the tip contact point on the other. Production parts tend to be a bit sloppy here. However, in addition to that problem is the fact that the push rod end and the valve stem end actually make different motions of rotation so the dynamic ratio of the rocker is always changing a little from the static dimension calculation. So using a push rod length that keeps the movement of the tip across the stem to a minimum, also keeps the ratio more constant to the advertised. God, I'm beginning to sound like Jim Miller!