Lisle valve spring compressor, junk?

You have to unlock the valve locks. Flip the head on its side, put your thumb on each valve and tap each retainer with a hammer to unlock the valve locks. Hit the retainer, not the valve stem. If you pay attention, you can feel with your thumb when the valve unlocks. You cannot "just compress" the valve springs without unlocking them first. That's why they're called valve LOCKS.