Oil burn cloud on engine deceleration

I used rope the one time I changed valve seals with the heads still on since I didn't have a compressor at the time, takes a lot longer but you can smack the springs as much as you need to get the valve locks loose. Just my $.02, not sure on the psi for air but I would figure 100 psi or more to make sure the valves can't pop open if the locks are sticky? My methods may not be correct anyway lol, should be a way to free up the locks beforehand...