Stud mount rockers (w/hydraulic lifters) are as easy as tightening them down until 0 lash and then giving them a 1/4 turn more. No feeler gauges necessary. If you buy them new they should come with instructions.
Pedestal mount rockers are adjustable, but you have to use shims and a feeler gauge to do it. A real pain in the butt compared to stud mount rockers.
To be fair, there are pedestal mount rockers that are adjustable without shims. They have an adjustment screw where the push rod meets with the rocker. If you plan to go to high performance heads in the future, a lot of companies only support stud mount rockers so what you get now won't be able to transfer to the new heads. That's fine if you have money to burn.
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351W 89 Mustang GT Convertible
[This message has been edited by jimberg (edited 07-23-2001).]