When I closed the valve some, I went from seeing 40lbs of pressure at about 4k to about 25lbs of pressure. I was not seeing much pressure at all at idle however, though water was still flowing out.you CAN'T eventually the block will fill and pressurize, and if you're just using a gated valve, all your doin is slowing volume, not pressure best thing you can do is give the motor bigger water outlets than what's goin into the motor.
you're feeding the motor with a 3/4 hose, then y-ing to 5/8ths' to the motor
well you should have 2 5/8th hoses coming out as well.that way the block can never really build much pressure, yet it'll see a volume of water. maybe a prob getting temp up that way though.,