What makes 1.6 rockers either fit an LT1 or not? Seems like it would be a universal part for all 350 motors. Are some brands able to be exchanged with stock ones without having to make any clearance in valve covers?

 

The LT1 rockers are Self Align rockers you'd have to run guide plates if you choose to run standard 350 rockers and harden pushrods..The Self Align rockers are a bit high in price but bolt on without any use of guide plates and sometimes modification to the valve cover..The only issue is the Valve cover rails on the bottom some cut them off others just straighten with some visegrips to clear the rockers. Also if you change rockers make sure you change valve springs since stock will not be able to handle the added lift.

 

Specifically you need narrow-bodied rockers.

 

Like stated earlier you will probably have to clearance the bracing on your valve covers. Some rockers don't require it, but it's probably not a bad idea to give yourself a little extra clearance just in case.