Whats the difference between the 2 roller rockers? How do self-aligning self align themselves?

 

This refers to the technique used to keep the rocker tip on the valve stem tip. Self-aligned have a little tang or projection either side of the rocker tip/roller, which locates the rocker on the valve.

Non self-aligned uses either: guide plates, or narrow slots in the head. Both these techniques act on the pushrod, and thus keep the rocker in place.

You can only use one of these techniques, or they may cause a bind.

Do a search for more details, there is tons of info on this.

 

Self-aligning are sometimes called rail rockers.
I recall reading where the rail rockers are all closer to 1.5:1, while the older rockers are actually closer to 1.45:1. This seems plausible to me.

 

http://forum.grumpysperformance.com/...+rockers#p7458


in this picture the self aligning rocker is the center one with the raise ridges that keep in centered on the valve tip , the two end rocker require guide plates