I finally got my vortecs.

I have read throught the deff guide 9 million times, but I still have a couple of questions.

Will I need a longer than stock valves to accomodate a lift up to .520? I already understand the machining invloved on the casting to do this. The valves that I bought my vortecs with look like they have recently had a valve job.

What lift are stock valves good for?

Valves don't care about lift, it's only the seal to retainer clearance that determines how much lift you can have. That clearance can be increased with a different style retainer, longer valves, or (the cheapest method) by trimming down the guide bosses.

make sure to check coil bind for the springs you use. determine installed height minus coil bind and that will let you know how much lift you can run for your springs...provided you have adequate retainer clearance. I think you need about .035 safety factor. 1.850 height - 1.25 coil bind is .600 difference/lift. then subtract the safety factor of .035, so you should be able to run a cam with .565 lift.

Some of the other guys can add more info or correct me if I am wrong.