Self aligning rocker arms...
Essentially it means that the tip is designed in such a way that it cradles the valve stem and keeps it from turning off sideways.
You must provide directional support for the rockers somehow, if you don't run self aligning rockers you will have to install hardened push rods and guide plates in order to use them. Non Vortec heads use machined ports in the head surface to align the push rods.
The factory Vortec heads use light, single-wire valve springs with a damper that generates between 70 and 80 pounds of load on the seat.
Because these heads are meant to work with a 1.5:1 rocker, their tall valve guides can only handle maximum valve lifts of around 0.420 inch. Anymore lift and you will need to perform some engineering work to make it work.
Lets say you have a compression ratio of 9.0:1 with a 7 6cc head and .021 gasket.
Then you change the head to 64cc and the gasket to .039 and you get 9.79:1
9.79:1 would require a higher grade octane fuel to prevent engine damage.
If you are just concerned about the puff of smoke at start up, replace the stem seals and check the valve stem wear...
Just my two cents worth...
