what is the max lift you can get away with on a set of j heads with out doing any mods do them

I'm assuming you would at least put valve springs in them.

Keep the lift under .500 and you should be ok.

my first experiance with a cam change on a small block saw a failure at the valve lock area. the grooves were hammered out. turns out the bottom of the locks were touching the top of the guide. this cam was 520 lift.

ya that what i thinking will happen im running a 509 with no problems so far but was thinking on bigger

Just machine the guides down and go to the Viton
seals at that time..... very easy to do

If you use the OEM type umbrella seal all you need to do is trim the tops of the guides some with a cut off. It is not a critical area and don't take a precision cut unless you use teh Perfect ccircle type of seal. Just don't leave any burrs on the inner guide area. There is plenty of guide there that you won't hurt anything.

Using retainers/locks with a higher install height like they do in this article would help"

http://www.compcams.com/Community/Articles/Details.asp?ID=-738676943

i was thinking that also as to cutting them but if i gotta take the heads off to do that im gonna go all the way and do it right that guys