How to adjustable rockers??
Can't say that I've heard this before, the only way to increase lift with rocker arms is to use a different ratio...1.5 stock....they make 1.6 and 1.7s that will increase the amount of lift your cam has, but never heard of an adjustable ratio rocker arm.
Have a look at this link...
http://www.wallaceracing.com/rockercalc.php