Okay, My Book on Cooling
I'll give a little back ground before I get to deep into this subject. 1st, my only experience with Jets has been with Chevy?s but I can assume Fords and Olds are plagued with the same problems. How to keep the motors at a constant normal running temperature. These are the things we have to consider. A) We run a motor at higher RPM for longer continuous time than which the motors cooling system was designed, and most have some type of performance enhancement, be it cam, higher compression, bigger carb and so on. These further adding to the internal heat of the motor. B) The water we use to cool the motor is not the temperature in which the motors cooling system was designed to use, and this water is rarely the same temature day after day C) the pressure at which the water is fed to the motor is less constant and worse can be greater at times then it is capable of handling.
Luckily we have had experts through the years try different experiments to solve or rather compensate for these problems at their expense to remedy the cooling process. In the 70s, a Jet motor was lucky to have more than 100 hours before a rebuild. Now we can expect more than 300 hours out of a farley mild BB. Mild being under 400HP. Above that you compound the problem 10 fold. I will start with
A). Higher constant RPM means an increase of internal heat accumulation with limited ability to compensate the cooling of motor. With the advent in the 90s of synthetic oils, which have greater ability to dispense this heat, our longevity has been greatly enhanced. Because air flow through an oil cooler is almost imposable, our greatest oil cooling system is already provided to us. Our Oil Pan. You probably say what? Yes, moving your bulge pump water level about a half inch above the bottom of our oil pan is a wonderful oil cooler. The synthetic oil then has a way to dispense this heat through the pan to the water around it. My bulge pump sits right in front of the oil pan sump, not in the back of the boat.
B) The water we provide to cool the motor is far from the constant temperature of the closed circuit, 140 degrees or so, that the cooling system was designed. How do we compensate for this you ask as we can?t heat the water before it enters the block? O, but we can. By recirculation a small amount of water back through the motor we can provide water that has a closer temperature to what the motor has been designed for. This believe it of not has added the greatest amount of stability and longevity to our motors. Having a motor sit at Idle, warming to a running temperature as we motor out of the "No Wake Zone", and then blasting it with a large amount of fresh 65 degree water as we burst out of the hole is one of the most damaging things we can do. When you?re pulling a skier out of the water, you do this over and over again. So how do I resuculate warm water back into the motor you ask? On the odd # head, between plug #s 5 and 7 there is a port. Some use this for their water temp sensor which is a poor place to have it as it is only accurate for that one area and not the whole motor. I suggest you move it to the intake right next to the thermostat housing. That?s were the water exits the motor and that?s the temp you care about. I'm not sure the size of this port but install a (BRASS or COPPER) NOT STEEL) nipple around 4 inches long. On the end of this nipple install a One Way Check Valve with arrow pointing out of the block. If your header or exhaust manifold is in the way use an elbow then the valve. Adapt a hose no bigger than 1/4in ID to this Check Valve and run it back to the water feed coming out of your pump. Let?s stop here and I'll pick this back up.
Now C) Water pressure. Regardless if you choose to run with a thermostat or not, which I recommend you do and I'll get to that later, you need to regulate this pressure. Any one that knows anything about closed circuit cooling system, like the one in your car, knows that you have a cap on your radiator. This cap is also a pressure relief valve. You can look right on it. Most are around 17 lbs. An optimal water pressure for a BB is about 14.5 lbs or a little above barrow metric pressure. A fresh pump is capable of 45 lbs or even higher above 5K RPM. Anything above 22lbs is certain for disaster. Blown head gaskets if your lucky. Cracked heads and bent rods more likely. A pressure relief valve placed right after the water feed out of the pump will control this to a safe pressure for your motor. This is were I return to the recalculated hot water. As the water coming from the pump exits the pressure relief valve I have installed another "T" fitting. This "T" is 5/8 x 5/8 x 1/4. This is were I introduce the recirculated water into the lake water thus heating it to a more optimal tempature and preventing sudden cold shots of water to an already warm motor.
I will end with probably the most controversial subject, Thermostat or no Thermostat. Few people understand the 3 functions of the thermostat. Yes, three, The 1st one of course is to allow the coolant liquid to stay stagnate and allow the motor to reach its optimal temperature before cooling begins. 2nd, is to hold this temperature relatively constant as it opens and closes as the internal temperature changes with RPM. The last and least known is to slow down the coolants speed as it passes through the motor. We don't have the luxury of providing our motors with the highest technology in coolants that have ingredients to absorb heat. By slowing down the speed in witch the water passes through our motors we increase its ability to absorb the heat and thus carry it out of the motor. If you look at a thermostat you can see how small the opening are compared to the hole it fits in. This is by design relatively small to regulate the speed inwich the water can flow. If the thermostat is left out the efficancy of the water is greatly reduced and because we are running water through the motor, volume can not make up for this. If you still choose not to run a thermostat I would suggest ripping the valve mechanism out of it and just install the body to help this efficiency. Here is a good way to check this efficiency if you don't believe me. Run your motor above 3500RPM once around your favorite lake and shut it off after you have come to a stop. Now watch your temp gage climb as it will normally up to about 195 but should not go above 205 or so with a thermostat. Without it, it will surely climb above 220 in witch you have now created steam and steam creates pockets of air and pockets of air in cooling system decreases efficiency which increases temperature. Temperature increases ware and ware decreases longevity and that increases cost and cost decrease fun and that what this is all about. That?s my 2 cents. Take It or Leave It. Agree or Disagree. Up to You. My Motor Runs 185 All Day and I guess that is what matters. To Me.
Good Luck and Stay Cool
Wild Thang
