I'll go with the heads are off the block. If they leak, at the very least, they'll need lapping. Got to remove one to see if it's leaking due to crud / carbon, rust, wear or burned.
Why is it apart and being tested?
How much leakage?
Ideally someone with a lot of significant wdoerjnwc Gloyale tells you what he’d do, I would just assume the valves are dirty and just clean and lap them. Might as well replace the valve stems seals while it’s apart, maybe depending on the reason it’s being worked on as well.
Thank you guys!
That is the answer I was looking for.
I removed the heads because of leaking antifreeze.
Since the heads were off I decided to check the valves and filled the exhaust and intake ports with water. That is how YouTube shows to check for leaking valves.
I will get a spring compressor, remove the valves, and see what conditions they are. I have never thought that the leakage might be just because the valves have a carbon built up. We shall see.