Electric or mechanical raw water pump

[nauti dreams]

I recently got a 76 220 ov it has a 302 and a alpha 1 out drive.

I'm one of those people who like to modify things to make them last as long as possible. I am converting the engine to a closed loop so I can run antifreeze with a heat exchanger. I want the water from the out drive to cool the manifolds only and have a separate pump for the raw water to go through the heat exchanger. I figure I only need 10-12 GPM to go through the heat exchanger.

Would a direct drive or belt drive raw water pump be overkill. Is there an electric option?
The pump would never see hot water, after the exchanger it will dump over board.
Thanks

 

[hottoddie]

Boy that's an old motor to do a fresh water conversion on. Has it been in fresh water it's whole life? If so can you locate a full fresh water cooling kit for a 302. You'd be better of having the anti freeze cool the block and manifolds and let the raw water from the heat exchanger exhaust out the risers and elbows like other boats with full fresh water cooling.

 

[nauti dreams]

Its a new block and heads. I'm building the kit. I'm trying to eliminate extra heat from going through the out drive. I've read that through hull exhaust boats have a longer life on their out drive due to reduced heat but I like it quiet and thought ide lose some heat elsewhere. Maybe I'm over thinking it but wanted to hear others thoughts.

 

[Lazy Daze]

I wouldn't worry about the exhaust heat going through the drive. I don't think I've ever came across a drive that went kaput for that reason. I suppose in a "lab", there could be a measurable difference, but when it comes to real life... it's not enough to matter. Change your gear oil on an annual basis, use the synthetic Merc stuff and have a regular maintenance program for your impeller. That drive should last decades.

 

[nauti dreams]

I wouldn't worry about the exhaust heat going through the drive. I don't think I've ever came across a drive that went kaput for that reason. I suppose in a "lab", there could be a measurable difference, but when it comes to real life... it's not enough to matter. Change your gear oil on an annual basis, use the synthetic Merc stuff and have a regular maintenance program for your impeller. That drive should last decades.

I was going to let the exhaust heat go through but wanted to contain the engine heat away from it with a separate system. Plus I live really close to the beach and it will see salt water was my main reason for wanting the motor on a closed loop.

So do you think im trying to over complicate it? Should I have the fresh water from the exchanger dump into the exhaust like normal?

My original idea was to have the water from the out drive go straight into the exhaust and back out the drive and have a separate pump bringing fresh water for the exchanger only then back overboard.