Reply to "double water pumps."

Things I've learned along the way ...

there are two cooling system philosophies

The first (and older philosophy) is to circulate the coolant slow enough to give it time to thoroughly absorb heat in the engine block and thoroughly exchange heat with the air in the radiator. This is the philosophy espoused by Carroll Smith in his series of books about race car engineering.

The second is to circulate coolant as quickly as possible, this relies on the high differential temperature between the engine block and coolant to transfer heat quickly. The goal of this design to to eliminate the temperature gradient acros the motor; i.e. the cylinders are cooler at the bottom than they are at the top which creates a small difference in cylinder ID and therefore a small difference in ring performance. This is the same reason some race teams reverse the flow of coolant through their motors.

The Pantera cooling system was designed adhering to the first philosophy. For instance the purpose for using a two pass radiator is to slow down the coolant and increase the time it spends in the radiator. Also notice the small size of the under-car pipes running between the radiator and the engine.

To properly convert the Pantera cooling system to adhere to the second philosophy requires a lot of parts replacement and modification, as John Taphorn has done.

Evans cooling says a radiator the size of a Pantera radiator with a 3-1/2" core is good for a 500 bhp motor in racing conditions.

The popular belief is that its easier to pull air through a radiator than it is to push air through a radiator. Therefore the open core design of the Hall Pantera Phoenix radiator is the best choice for pusher fans, the other aftermarket Pantera radiators are better off using puller fans.

A shrowd definitely improves the performance of puller fans for stop & go driving, but it adds restriction to air flow at very high speeds (i.e. 120 mph+).

The crankshaft pulley found on the Pantera's 351C motor is the same size as the water pump pulley, providing the same pulley ratio as any other Ford product not equipped with A/C. But the tubing between the engine & radiator is smaller in diameter, longer, and has many more bends. This restricts the flow rate of the coolant. Some (including me) feel the coolant flow rate is insufficient for stop & go driving.

Several guys have installed the Flow Kooler coolant pump and have reported improved cooling system performance under stop & go driving conditions. The Flow Kooler pump is designed specifically to increase coolant flow at low engine speeds. Their model 1648 pump has two 5/8" ports, making a convenient way to connect the bottom connection of a header tank to the system.

The Edelbrock coolant pump also has two threaded ports which makes a convenient way to connect the bottom connection of a header tank to the system. The curved blade impellar of the Edelbrock pump raises the engine speed at which "cavitation" sets in, I conservatively estimate it will save 5 BHP at 6000 rpm. Good Ol' Vic.

Stewart Components stage 4 coolant pump for the 351W is rated at 160 gpm! It can be modified to fit the Cleveland. I believe Larry Stock sells them. I doubt it will flow 160 gpm in conjunction with the Pantera's restrictive coolant system, but it should raise the cooling system's flow rate significantly. I'd call that the quick and dirty way to achieve high coolant flow. The pump has a high-tech 8 vane impeller that only uses 3 bhp at 4500 rpm. I don't know if it has any heater hose connections, its a racing pump afterall. That may require some fabrication.

The tank that DeTomaso calls a "system tank" is obviously designed to be swirl tank. A swirl tank (or de-gas tank) is a tank that removes air from the coolant that is picked up in the engine, before it gets to the radiator. But the "system tank" cannot function as a swirl tank unless the radiator cap is removed and replaced by a simple bleed hose connection that can be plumbed to a header tank. More on header tanks later.

When some guys pull the under-car tubes out of their Panteras they find them full of enough rust chips to restrict coolant flow, some bad enough that they are plugged solid; others find the tubes clean as if they were new with no rust chips at all.

Most Pantera cooling system woes are a result of the wrong thermostat being installed in the Cleveland motor.

The second biggest problem with the Pantera cooling system is the vent system as designed doesn't vent at all. Air accumulating in the radiator has no where to escape, as more air acumulates in the radiator it slowly detracts from the active surface area of the radiator. The fix for this is conversion of the expansion tank to a header tank and afterwards relocating the radiator vent to the new header tank.

When chasing problems related to the poor performance of the cooling system I recommend 4 things: (1) make sure the under-car tubes aren't plugged (2)install the Robertshaw 333 series thermostat (3) modify the vent system (4) install high air flow cooling fans appropriate for the type of radiator installed in your Pantera (or a radiator appropriate for the type of fans). The Phoenix radiator and Meriah fans are a natural pairing, as are the Fluidyne radiator and Flex-a-lite fan kit. The Ron Davis radiator includes puller fans.

My suggestion would be to do these things first if you haven't already done them ... before you do anything else ... because you may not need to do anything else.

-G