Editing Bulletproof cooling system (section)
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==Bulletproof cooling system tips== *Clogging and leaks are two of the most common radiator problems. Bugs, dirt, and debris can block airflow, and limit the radiator's heat-dissipating characteristics. Thus, it's recommended to "back flush" the radiator and cooling system when changing coolant. This helps to clean out deposits, and flushes the remaining coolant from the engine block. You can back flush the radiator by running water through it in the opposite direction of regular flow. Typically, after draining the radiator a t-fitting can be installed in the heater inlet hose. This fitting gets connected to a pressurized water hose, and the system is reverse flushed. Do this until clean water emerges. *A rough guide is to use a radiator at least as large as the one that was originally used to cool the engine, with the same or more radiator cores. However, it's important to note that additional rows don't add a proportional amount of cooling, i.e. a 3-row radiator does not necessarily offer 50% more cooling than a 2-row radiator. This is because subsequent rows receive warm air from the rows in front of them. However, adding radiator frontal area IS proportional, but this usually causes fitment issues, so additional rows are generally the only viable choice. Also the radiator design and materials can have an effect on the radiator efficiency; a larger radiator is not necessarily a better radiator. *Oftentimes, the cheapest and most bulletproof way is to use the largest radiator that will fit, along with the fan type and size, and shroud that was designed for the radiator from the factory. *Use a full shroud, with the radiator positioned so that the fan blades are half-in and half-out of the shroud hole, and no more than 1" of clearance between the shroud and the fan blade tips (just enough to prevent interference when the motor rocks on its rubber mounts). [[File:Thermo fan clutch.jpg|thumb|210px|Typical thermostatically controlled fan clutch]] *Fan recommendations: OEM 18 inch, 7-blade steel fan with 2" to 2-3/4" pitch. The pitch of a fan can be measured by laying the fan down on a flat surface and measuring from the flat surface to the edge of the fan blade. Fans that are relatively flat (such as a flex fan) may not move enough air at idle and low engine RPM to cool the engine properly. *When possible, use a thermostatically controlled fan clutch. While a thermostatically modulated fan clutch is an effective means of operating the cooling system's fan, a worn or defective fan clutch can cause overheating if left undiagnosed. Sometimes they may appear to be OK when cold but they will free-wheel when hot. <br style="clear:both"/> *Water pump and crankshaft pulleys sized according to what was on the engine from the factory. On a street motor, shoot for 1.2 to 1.3 times crank speed for pump pulley speed. This is usually true until you get to 3.55 gears and numerically higher, then 1:1 works better. Most 1960s muscle cars are 1:1. Sustained pump speeds over 4200 rpm can cause cavitation. Race vehicles may use a 2.3:1 ratio for a 9000-plus rpm engine. *On a carburetor-equipped engine, often a 180º thermostat is used, although a little hotter thermostat rating (190º-195º) may make the motor more responsive and add a little fuel mileage. It may also help to burn off some of the by-products of combustion, such as moisture and acids which form and get into the oil. Motors using EFI induction should use the thermostat temperature specified by the factory for that particular motor to prevent false input to the computer and consequent problems. The sensor pill goes toward the motor. *Use a spiral-wound spring in the bottom radiator hose, to prevent collapse of the hose. *Use the proper pressure cap for the radiator being used. *Ensure that there is adequate airflow from the engine compartment to allow the exit of the air drawn into the compartment. In custom applications this might require the removal or surgery of inner fender panels or using spacers to raise the hood of the car up an inch or two at the back. *Maintain the proper coolant/water mix to prevent freezing up in winter. Water transfers heat better than coolant, but some coolant must be used to prevent freezing. Using a 50/50 mix of coolant/water is a necessity for motors using aluminum parts. Plain water will turn aluminum into oatmeal. *Before installing the water pump, grasp the impeller with one hand and the drive hub with the other and twist to make sure the impeller is tight on the drive shaft. If the driveshaft is not spinning the impeller, no water is being moved through the motor. This problem can be the source of great frustration and is hard to find unless you know to look for it when installing the pump. *Although it may not be necessary, the concept of a "water pump conversion disc" can be researched. Flow Kooler originally marketed flat aluminum discs to be riveted to the backside of the stamped steel impeller of the water pump. With an iron impeller, a steel disc could be welded or brazed onto the impeller. Such a disc wouldn't be that difficult to make. Space the water pump backing plate back farther with a couple of gaskets to prevent interference of the rivet heads on the backing plate if riveting a disc to a stamped steel impeller. More info: [http://www.smokstak.com/forum/showthread.php?t=11774 brazing cast iron], [http://store.summitracing.com/partdetail.asp?part=BRA%2D4375%2D07&autoview=sku Flow Kooler water pump conversion discs]. This disc could make an appreciable difference in the flow of water at engine speeds under 3,000 RPM. On the other hand, Howard Stewart of Stewart Components (the guy with the water pump dyno), says that these discs have little to no effect. **[http://www.FlowKooler.com FlowKooler]established a new standard for hi flow water pumps in 2013 with the release of a full line of precision machined billet impeller. The impellers have larger diameters and additional vanes and by reducing the clearance between impeller vanes mating surface create an appreciable improvement in flow rate and block pressure. This pressure increase helps prevent formation of steam pockets and hot spots on the cylinder wall and can also prevent cavitation of the impeller.
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