We extend to you a cordial "WELCOME ABOARD !" Come on in, make yourself at home, we are a friendly group of enthusiasts, and we also appreciate the classic Chris Craft Roamer, Corsair, and Lancer boats too , as they are all on the same family tree and share much in common !
Corey recently requested info about the conversion of a STANDARD COOLING system to CLOSED COOLING system, due to the fact that he purchased a freshwater boat that is being relocated to salt water.
This thread particular thread you are reading (with all it's tips and diagrams) is a great base to work from. Look closely at the diagrams on the first post showing STANDARD versus CLOSED, and that pretty well tells the story of what will be needed.
The fresh water (STANDARD) system will need to have one side of the T fitting blocked off so all of the intake water flow goes directly to the heat exchanger.
You can adapt a stock system to the motor, or you can upgrade to larger heat exchangers that are offered new on the aftermarket or perhaps from another model of boat, as long as the exchangers are equal or larger to the ones used on the 427. Be advised, the CLOSED system requires a different thermostat so if you are buying a heat exchanger system from a recycled 427 motor, be sure to get the thermostat with the parts if you can. They run a little hotter.
I have STANDARD and CLOSED system on the 427 (STANDARD in the boat now, CLOSED in the basement on my spare motors) so I can offer details if anyone wants to do this conversion with stock parts, or just needs good documentation.