Just bought my first jet boat and I’m thinking of taking it out next weekend but I have some questions can you guys please help. Is this my gate valve to control water pressure going into the block? And also when I get to the launch should I let it run on the trailer with the valve half open and let it warm up before doing adjustments?  What is the highest and lowest temp range it should stay? It’s a bbf. Thanks In advance.


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 that style has the most control over the water pressure that enters the motor. Most guys crack it a little on initial fire-up on the trailer and then open it more as the motor warms up. Keep it on the trailer and let it warm up and keep turning the knob until you get it where you like it.

With headers like yours, 130 is plenty.

This is a single pass system, lake at 80° engine exit temp 130. (that's adding ~50°)

This is not a car. Don't run it at 180. That would be adding 100° to the exit temp.

Dan'l