Plumbing the water on a Chev, Holden and is similar on most other dog clutch style ski boats. Rolco thermostat control system. This system is designed to let your motor run near the thermostat temperture rating. All thermostats must have at least a 3/16" hole drilled though them to prevent a air lock underneath.


Below is the tipical plumbing of the water system to suit a dog clutch drive without a thermo control setup and driving off the timing case end.


Below is the tipical plumbing of the water system to suit a soft clutch drive with aTawco thermo control setup and driving off the flywheel end.This system is designed to let your motor run near the thermostat temperture rating.


NB. The water should always enter at the lower point of exhaust manifolds and motor the exit out the higher point to enter into the exhaust pipes.
We don't recommend using taps or other devices to restrict water flow anywhere in the system. If wishing to raise water tempature in the engine with a thermostat you must use have in place some sort of releif valve so not to restrict the water that passes through the exhaust manifolds which requires full water flow first.
  Recommend all boat owners to fit a water strainer filter system before the water pump to eliminate the possibility of ingestion of gum nuts,weed or any other rubbish in the water that could ruin the water pump impeller. 
Remember if you cannot run your hand along the outside of the exhaust manifolds while the engine is ideling most likley the pump is not operating correctly and requires investigation.

Hoping this information will keep you on the water longer.

Regards Bob (R&M Precision Marine)