On ej25 engine, where is the optimal cam sprocket position to set intake and exhaust valves while  heads on the workbench. Can't use the FSM procedure because that's done with timing belt on. On the bench the valve train doesn't want to stay at the 12, 3 , 6 and 9 positions.

Been doing it for years.  Every time I do head gaskets. 

Roll the cam until either pair of valves opens , stop them just at fully open and adjust the closed pair. Roll again till the pair you adjusted is fully open and adjust the other pair. Then move over to the next cylinder and repeat. I do it twice just to check.

I have checked after head install (belt on) and never had to readjust.

 

This is not as accurate as the factory procedure. Do not set them super tight .  You can easily recheck after you have the belt on.   

there is one position on each cam where there is are no valves open.

 

I ussually set the cam up so that when I put the carriers on all lobes are facing down or sideways.

 

It's kind of a sweet spot where turning 10-20 degrees one way begins to open an intake, and a roll of the cam the other way just begins to open the opposite exhaust.

 

I have no idea where this spot is relative to teh cam arrows actually.  I've never needed to know.  Just find that sweet spot where no valves are under tension.