SpudFiles

Im using a 2" valve sprinkler valve that looks similar to the one below. I plan to add a 3/4" ball valve where the solenoid is because it is conveniently threaded there. The small hole leading from the upper chamber to the solenoid chamber is about 5mm. Is this large enough to be effective or should I try to enlarge it.

Plus, my valve has an optional 2nd inlet. Would it be ok to open it up and use both or would it create some sort of turbulence?

well the bigger you make the hole the better but there will be a point where it no longer improves performance. i say make it as big as you can without weakening the structural part of the valve. if you do use both inlets it may increase performance a little... but that would only be if the inlet was the bottle neck and not the diaphragm sealing face part.

i really think to should attatch the ball valve directly to the pilot chamber. It would greatly improve opening time and thus giving you better performance. As to you question about the second inlet, I have seen people use both inlets, but it's not necassary.

I would have liked to use the valve above the main chamber but my diagram doesnt show that there is about a solid inch of angle plastic above it and a vent. I'm not confident I could tap a good hole.

To increase the size of the small hole to the solnoid section I just use a drill right?

yea pretty much, and remember to plug the small tube that goes from the solenoid to the outlet or your valve will never seal.

Just normal epoxy o both sides of the hole for that right?