302 (5 liter) Ford closed/fresh water cooling

Discussion in 'Gas Engines' started by missinginaction, Dec 4, 2017.

  1. missinginaction
    Joined: Aug 2007
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    Location: New York

    missinginaction Senior Member

    Since I restored my 1973 Silverton Sportster 25, I've been venturing farther and farther from home over the past three years. This boat has it's original 302 Ford and is raw water cooled. Since it's a fresh water boat the engine is in good shape, no issues. It has about 1200 hours on the clock and I believe this figure is fairly accurate. The Hobbs meters worked when I inherited this rig. The previous owners (two of them) were good about maintenance. I did replace the exhaust manifolds, risers and exhaust system during the restoration. In a couple of years I'd like to start taking this boat down the Intercoastal to Florida. While the current engine runs fine I'm not comfortable with taking it 1200 miles from home. After all it is 44 years old.

    I'll probably replace this 302 with a rebuilt long block in 2019. I'm looking for a good source for materials that I can use to construct a closed cooling system. I can find "kits" on line for the 302 but they are front mounted and won't work with a v-drive a s the engine is reverse mounted and the exhaust system is in the way. Since it's a v-drive, I think that an off engine mounted heat exchanger would be my best option.

    If anyone has some recommended sources for long blocks and/or parts that I could use for the cooling system, I'd appreciate your input. As some of you might remember from my posts over the years, I like to plan my work in advance and accumulate all the materials I need before I start a job.


  2. 7228sedan
    Joined: Nov 2009
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    Location: New Jersey USA

    7228sedan Senior Member

    Hey MIA, I'm in a similar boat figuratively and literally. I have a 72 28 Luhrs with a FWC Merc 7.4L V-Drive. My heat exchanger is remotely mounted between the exhaust tubes on a bracket that mounts down back just in front of the rudder. From the look of your setup, your mufflers are too large in diameter to allow the heat exchanger to fit. Do those mufflers extend from the manifolds straight back to the thru hulls? If not, I'd say rework the plumbing to have a longer length of exhaust hose in front of the mufflers. My mufflers mount directly to the through hulls with about 2 feet or so of 4 inch hose on each side in front mounting to the manifolds. The other option may be to mount the heat exchanger on the back of the motor over the transmission. There were factory closed cooling kits from Mercruiser with both front mount and rear mount exchangers. You may need to Frankenstein a "kit" yourself but there's lots of parts out there.
  3. missinginaction
    Joined: Aug 2007
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    Location: New York

    missinginaction Senior Member

    Thanks for the reply 778 and happy New Year.

    I've been looking around and notice that there are a few suppliers that make "piggy back" style heat exchangers. You're right about those mufflers being pretty big. During the summer I'm surrounded by liveaboards on bigger boats. I'm on good terms with all of them because I can leave at 5 or 6:00 in the morning and not wake anybody up! While you can't see it in the photo I posted, those mufflers are pretty tight. Only about 3" of clearance between the rear flange on the muffler and the stainless through hull exhaust flange. I've removed the mufflers a couple of times to make modifications to the transom and have to remove the risers in order to get them out of there.

    I think that I'll be able to find a suitable exchanger that I could mount over the bell housing or beside the engine, as you suggested. I'd hate to start filling up the area between the engine and the transom with anything as it is a nice place to put an old blanket and sit down in there to do some maintenance. The older I get the less my back likes to be bent over.

    Probably the easiest course of action is to wait until I pick up a fresh long block and fabricate a bracket to hold the heat exchanger while the engine is sitting on an engine stand. Thanks for the suggestions and stay warm!
  4. gonzo
    Joined: Aug 2002
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    Location: Milwaukee, WI

    gonzo Senior Member

    The heat exchanger is connected to the engine and the raw water pump by hoses. As long as it it higher than the thermostat housing, any remote location will work.
  5. Lepke
    Joined: Sep 2015
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    Location: Oregon to Alaska

    Lepke Junior Member

  6. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    I've seen some of the 12 VDC pumps and though they have good guarantees, I've never trusted them. I'm a big fan of closed loop cooling systems, but prefer bullet proof pumps. Maybe a 12 VDC pump as a standby replacement, sitting in a cabinet will work, I just don't trust them.
  7. Sparky568
    Joined: Jan 2017
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    Location: Northeast USA

    Sparky568 Junior Member

    Discount Inboard Marine.

    www.skidim.com http://www.skidim.com

    Lots of hard to find ford parts here. I put about 2700 hours on a 302 and was a running take out when I parted my boat out. Great engines. By the way I have a Holly 4160 carb if you are interested.

  8. missinginaction
    Joined: Aug 2007
    Posts: 1,103
    Likes: 254, Points: 83, Legacy Rep: 512
    Location: New York

    missinginaction Senior Member

    Thanks Lepke and Sparky for the links. I'm looking through them. Thanks for the offer on the carb Sparky. I put a new Holley on that motor just a few years ago. Just a quick note to Paul. I'm making these improvements in Pearl for a trip down the intracoastal during the winter of 20-21 or 21-22.
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