Head from d16y5 (vtec-e)

Its normal?

 

Think back to that old Sesame Street song, "One of these things is not like the other".

 

I believed that both valves open and close at the same time, same length

 

Are any of the other valves like that? Let's pretend for one minute that I know nothing about what you're asking. There are 4 of those chambers. If all four look the same then move on. If only one, then it's not normal. Just assuming because you only shot one out of four.

Maybe that was the question you were asking and not being at all clear?

 

only happened in the intake valves, all chambers.
Then is normal?
When Vtec kick in, both valves open?

 

For the Y5 head, that is normal. It uses a dual stage engagement. Before VTEC, only three valves open. During first stage, three valves open fully, and the fourth half opens to create a vortex of air to better atomize fuel. During second stage, all four valves fully open.