Freshwater upgrade for a Ford 302 V-drive.

Discussion in 'Gas Engines' started by missinginaction, Dec 27, 2018.

  1. missinginaction
    Joined: Aug 2007
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    missinginaction Senior Member

    Before I start let me say that I know many will tell me something like "you should put a small block Chevy in there". I get that but the existing engine is in excellent condition. It's a 73 with about 1.200 easy hours on it. Typically slow cruising at 1800 rpm. No leaks, anything that bolts to the block has been replaced in 2014. It's raw water cooled and has always run in fresh water. The existing cooling system works fine. Based on what could be seen when the engine was out of the boat the inside of the block was remarkably clean. No sludge in the oil return galleries. I'll post a photo....

    126.JPG

    I'm going to take this boat to Florida in 2020 via the Intracoastal Waterway. Spending a long time in salt water I think it's a good idea to invest in a fresh water or closed cooling system. I'd prefer to run a "full system" rather than a "half system" and run antifreeze through the exhaust manifolds. I've been doing my homework and understand how to plumb a full system. I'll need to fabricate a block off plate for the manifold to riser joint. I'll mount a "piggy back" style cooler in the front of the engine, above and between the mufflers. Something like this.......

    98146.JPG

    If you look at my engine and the cooler you'll see that I need to install the cooler with the fittings facing the engine. For this discussion though just look at the photo and please follow along. The two studs in the center/bottom of the heat exchanger are an oil cooler mount. As I understand it the cooler will be installed as follows.

    1. 90 degree fitting on exchanger lower left is raw/sea water intake from Sherwood pump.
    2. Pipe exiting exchanger with tee fitting is raw/sea water outlet from exchanger. Hoses attach to the tee and one goes to each exhaust riser to quench the exhaust.
    2. Large fitting on bottom of exchanger feeds antifreeze to engine water pump. Antifreeze is pumped through the engine and exits the thermostat housing mounted on the intake manifold. As the antifreeze exits the thermostat housing it travels to the exhaust manifolds, travels through the manifolds and then travels to the two fittings on the expansion tank (the top tank, left and right of the pressure cap. The antifreeze then cycles through the expansion tank down through the exchanger and the process repeats itself.

    If I've got any mistakes in my plumbing please let me know. I think I'm OK with this.

    I have two major questions though.

    1. I've looked all over and cannot find a marine thermostat housing for a small block Ford that's designed for freshwater cooling. The way I see it I could use an automotive style housing. Something like this.......

    th25_1.1700.jpg

    The issue is how to get the antifreeze flowing out of the thermostat housing to the port and starboard exhaust manifolds. I think I've solved that issue by using a bronze tee fitting between the thermostat housing and the manifolds. Something like this....

    1858695.jpg
    You can attach hose barb fittings to this tee and use it as a splitter. This would solve the plumbing problem and get coolant to the manifolds.

    One last issue. How are the manifolds cooled then the thermostat is closed? Ford automotive thermostat housings have a bypass circuit that typically (in a car), runs from the thermostat housing to the water pump. I'm wondering if I could drill out the bronze tee fitting, install a nipple and get some coolant to the manifolds via the bypass circuit while the engine is warming up. It might delay the warmup a few minutes but since it's a fairly small amount of coolant, would it be a problem? I'm concerned that the manifolds could get quite hot with a closed thermostat and no coolant flow. I don't want to damage the manifolds.

    I realize that this is a long post but I wanted to cover all the bases. Please feel free to weigh in with any suggestions.

    Thanks and Happy New Year!

    MIA
     
  2. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    The bypass, when installed in a car, feeds the heater core. If you are running the manifolds through it, the warm up will be faster. Make sure that the heat exchanger is sized for manifold cooling. Otherwise, the heat exchanger is the same as a car radiator.
     
  3. missinginaction
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    missinginaction Senior Member

    I see what you mean Gonzo. If I didn't run bypass coolant through the manifolds wouldn't there be a risk for hot spot development in the manifold water jacket? That's my biggest concern. Without that bypass connection it seems to me that there would be no coolant moving in the manifolds until the thermostat started to open. MIA
     
  4. gonzo
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    gonzo Senior Member

    The bypass lets the coolant circulate through the engine block and manifolds before the thermostat opens. Basically it is a closed loop until it warms up, and then it opens to the heat exchanger. If you didn't use the bypass I agree the manifolds would get hot spots and cause problems.
    https://www.boatpartstore.com/images/coolfig2.jpg
    Buy Fresh Water Closed Cooling Systems for Mercruiser, OMC and Volvo Penta | PerfProTech.com https://www.perfprotech.com/buy-fresh-water-closed-cooling-systems-for-mercruiser-omc-and-volvo-penta/category/1284
     
  5. missinginaction
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    missinginaction Senior Member

  6. 7228sedan
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    7228sedan Senior Member

    I can't see why they wouldn't work... I've use plenty of heat shrink for sealing wiring. The only downside is the need to destroy it for disassembly.
    I can definitely see the benefit to the increased contact area though.
     
  7. missinginaction
    Joined: Aug 2007
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    missinginaction Senior Member

    Just checking in at lunch. Good to see you're still around here 7228.

    I think I'm going to give those new Gates hose wraps a try on my engine to heat exchanger hoses. I'll stick with stainless clamps for the raw water part of the system

    Just this morning I've been working on designing a bracket and a couple of supports for the new heat exchanger. I've got the new v-drive in the laundry room. Wife's not real happy with that but I said "Do I really have to lug this into the basement?". I didn't want to leave it in the garage.

    I've finished the rotating frame for the dinghy. Test fit the frame onto the swim platform and it works, everything lines up as it should. That took some time because of the rotation and making sure the math was right. All that's left is some drill-fill-drill on the platform and installing some aluminum plate reinforcement.

    Looks like the weather will improve over the next few days so I'll keep at it. Since I'm retired now I have more time so this all should go more quickly provided I don't procrastinate on ordering parts.

    Have a nice weekend and Happy Easter if you celebrate it.

    MIA



    I'll post more when I start to get things installed. Still waiting on the new propeller but it should arrive in the next few weeks. Eight to twelve weeks lead time on that.
     
  8. 7228sedan
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    7228sedan Senior Member

    Oh yeah, I'm around... I pop in every once in a while to live vicariously through others while I continue the search for the next one.
    I had to fabricate a bracket to mount the heat exchanger to the motor in it's designed location on my Merc in the Luhrs. Luckily, the makeshift mount that was on the boat had the cradles that support the heat exchanger.
    I used some angle aluminum and steel tubing to build standoffs to mount the cradles to.

    upload_2021-4-2_13-22-22.png


    Looking forward to the end result, glad to hear you're still at it :)
     
  9. missinginaction
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    missinginaction Senior Member

    Nice neat front mount 7228. My install is a little different. The HE is designed for a small block Chevrolet, rear mount over the bell housing. The two top bolts on the Ford bell housing are a mere 1/4" different center to center. I'm using a piece of 3/8" 6061 aluminum bar to make an intermediate plate that will bolt to the bell housing. This HE is pretty heavy so I may need some additional support. We'll see once I get it in there.

    [​IMG]
     
  10. 7228sedan
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    7228sedan Senior Member

    Nice! My HE was from Mr Cool as well... nice unit that had zero issues kept the motor cucumber cool. Are you planning a full system including the exhaust manifolds?
     
  11. missinginaction
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    missinginaction Senior Member

    Full system. The only issue I have is that there is not a purpose built thermostat housing made to split out the coolant and send to to each exhaust manifold. No worries though. I have this worked out ( I think). The trick is getting coolant to the manifolds while the thermostat is closed. I'm using a Robert Shaw 160* thermostat and will drill a couple of 1/8" relief holes in the thermostat is allow some coolant to pass. If this isn't enough I'll drill a third. If THAT isn't enough I have a new aluminum intake that has two drilled and tapped sensor holes that I don't need. I can send more bypass through those ports if I need to but I'm hoping that the thermostat relief will be enough. I have a couple of old friends that used to race cars and they're confident that the relief holes will work.

    I've got the engine almost completely undressed. Along with the cooling I have the v-drive to install, I'm moving the engine back 1.75" for clearance (not rocket science but more work than it sounds), new intake, new exhaust manifolds, new valve stem seals (why not? I'm down there anyway.) and I'm pretty much done with the dinghy storage frame and just have to install it.

    It's just a matter of getting down in there and getting it all done. Still waiting for a prop, over eight weeks and still no update from Michigan Wheel. They're really backed up I think.

    I'll keep you posted.

    MIA
     
  12. 7228sedan
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    7228sedan Senior Member

    awesome. I hear that... my motor had a homemade thermostat housing made out of braised copper pipe and a 1/2 inch thick copper base flange. When I put in the new motor, I installed a new proper housing. If I remember correctly, the hoses from the housing went to the bottom of the manifolds as well. The hoses on the top of the manifolds went back to the heat exchanger. Mercruiser used Fords in the 70's did you look at Mercruiser part 889333? Maybe there is an off the shelf housing that can do the job.
    I actually had to move my motor when I first got the boat as I went from a 71C to a 72C Velvet Drive. Being a v drive as well, there's quite a bit of geometry involved in that for sure. Do it all while you have the access, you won't have an easier go at it.

    Looking forward to the progress!
     

  13. missinginaction
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    missinginaction Senior Member

    That Merc housing is no longer made. I've seen a few advertised online. They're either used and pretty decrepit looking or the seller wants the better part of $300.00 for one. It's just coolant. As long as it gets where I need it to go I don't have a problem with making up my own system.

    Your memory is right. Out of the thermostat housing, through the manifolds, through the heat exchanger, back to the coolant circulation pump and through the block again. Around and around. I'll figure it out.
     
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