What is the max lift for an LT4 valve spring? I did a search and after looking through 3 pages of threads, I didn't see the actual max lift of these springs.

 

.525"

 

525 would be the correct max lift as posted above, the hotcam is right at that with 1.6 rockers. If you plan to upgrade your cam at all, then upgrade those springs.

 

There is more too this than purely lift, ramp rates, is the lift achieved with 1.6 rockers like with the HOT cam or is the heavy lifter moving enough to generate that lift with 1.5s, light valves like the LT4 heads? Boosted motors will need more spring due to the pressure on the packside of the intake valve.

The LT4 springs are marginal for the HOT cam with it's mild lobes and achiving the .525 with rocker ratio, aftermarket cams will usually be more agressivly ramped and move the heavy lifter enough to get that lift without 1.6 rockers, both of which are details that will cause these springs to NOT work at .525 lift.
What do you want them to do and then maybe we can help you determine if they will work for you.