Gas boat water pump intake

[Andre girouard]

Hello. Building a scale military patrol boat powered by a homelite 30cc water cooled trimmer engine with clutch and water pump (powered by engine vacuum). Where should the pump water intake come from ? Right now on the rudder blade there are 2 water nipples, should i run a line from there to the intake or should i install a water pick up in the bottom of the hull close to the pump with a Y fitting { 1 line from rudder blade, 1 line from proposed pick up under pump, the other line to pump intake ) ? Thanks.

 

[Gary Parker]

I install vacuum powered water pumps on all my gas boats using a transom mounted water pick ups as pictured with the "v" cut out pointing forward to maximise water pick up (there is a grub screw to adjust).
The line from the pick up is routed to the intake of the water pump and from the water pump oulet to your cylinder head. The pick up lines from rudders can be routed singularly or with a Y fitting to exhaust manifold or other pipe cooling fittings as required.

 

[Daniel's Racing]

Take two lines from rudder fittings and Y them together and go into the pump.

Where you pull pulse from is important.

You want to go right into the bore of the intake NOT the carb pulse passage nor the crankcase.

The pulse in the intake BORE is incredible makes lots of difference at low throttle settings when you need the pump most.