water pump and pulley selection

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str12-340

str12-340

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This is for a moderately built small block on the street. My biggest concern is never having this thing overheat.

Water pump selection - there are a raft of aftermarket water pumps for small blocks out there and 6 and 8 impeller stock style pumps. What is the best choice for making sure my small block Dart never overheats even if I get stuck in a traffic jam in Palm Springs in August?

Pulley selection - to complicate matters, when looking through my bin of used pulleys, the AC water pump pulleys are smaller which I think means they spin the water pump faster If I can figure out alignment, should I use a smaller pulley?
 
I'm in Tampa Bay. The weather is Hot, Hotter, Hot and Rainy w/ Humidity, Way Hotter, Ect . Used the 66 273 a/c pully off my old Sat. Runs 180 in the Summer. Creeps a Lil at a long light. 180° thermostat...
 
Yes, use the smaller WP pulley. Not only does it spin the pump faster, it spins the fan faster for more air flow.
 
6 impeller flow more water. 8 impeller flow less. Most original AC cars I took apart years ago had 6 with the small pulley. non AC were 8 with the larger pulley. I ran a 69 cast pump and earlier crank pulley on a 70 aluminum pump system to under drive the pump.

With a Fluidampr it is a bolt on belt alignment, with a standard damper you need a 1/4 inch spacer,
 
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IMO, MoPar got it right. If you don't have a/c then don't use the a/c pulley or pump.
 
good information, Please keep it coming... anybody use any of the other aftermarket pumps beside Flowcooler?
 
str12-340 said:
good information, Please keep it coming... anybody use any of the other aftermarket pumps beside Flowcooler?
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I use the Milodon pump and run the pump at least at crank speed. Keeping the coolant in the radiator keeps it in the block longer. Think that through.

You want the coolant out of the block sooner. The higher the temperature differential between the coolant coming out of the block and ambient air temperature the less cooling you have and you work the cooling system harder.
 
Rat Bastid said:
I use the Milodon pump and run the pump at least at crank speed. Keeping the coolant in the radiator keeps it in the block longer. Think that through.

You want the coolant out of the block sooner. The higher the temperature differential between the coolant coming out of the block and ambient air temperature the less cooling you have and you work the cooling system harder.
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I think we're splitting hairs here... and, like anything else, depends on usage. Where I'm at, it's Hot. Then, it gets Hotter. If Ya Have the Airflow, that helps. The entire point of having Cooling Fins on a Radiator, is to Dissipate the Heat.... not disagreement, but when, Ambient Temps, are wacked, sometimes letting the Rad do its Thang, is pretty damn important... now, going back to Airflow. I was metal framing, and hanging board, with a Vietnam Veteran, for some Years. Good Personal Friend. The fan blew off his F-150, trashed the radiator, out by St. Augustine, I was in Middleburg. Over an hour away. I took him a Radiator, plugged it in, NO FAN. yes it was Wintertime in N FL, And Yes, I asked Dennis to roll about 50 ( NO One Told Dennis ****!) Never overheating on the way back. We may have missed a TCD once or so...
 
Ironracer said:
I think we're splitting hairs here... and, like anything else, depends on usage. Where I'm at, it's Hot. Then, it gets Hotter. If Ya Have the Airflow, that helps. The entire point of having Cooling Fins on a Radiator, is to Dissipate the Heat.... not disagreement, but when, Ambient Temps, are wacked, sometimes letting the Rad do its Thang, is pretty damn important... now, going back to Airflow. I was metal framing, and hanging board, with a Vietnam Veteran, for some Years. Good Personal Friend. The fan blew off his F-150, trashed the radiator, out by St. Augustine, I was in Middleburg. Over an hour away. I took him a Radiator, plugged it in, NO FAN. yes it was Wintertime in N FL, And Yes, I asked Dennis to roll about 50 ( NO One Told Dennis ****!) Never overheating on the way back. We may have missed a TCD once or so...
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You have to remember the longer the coolant is in the radiator, the longer it’s it’s in the block.

If you have 200 degree coolant coming out of the engine and an ambient temperature of 100 degrees you can only drop the coolant temperature maybe 20 degrees. Maybe.

There is some math to calculate all that out, but it requires me to use a scientific notation calculator and I’m not sure of all the variables. But a 20 degree drop is pretty close.

Now get the coolant coming out of the engine at 180 degrees. Because the coolant isn’t staying in the engine as long, it picks up less heat. Picking up less heat makes it easier for your 100 degree ambient temperature to get that 20 degrees out of it.

Of course, your thermostat opening point and the ability of the rest of the cooling system to do its job will determine how well the engine gets cooled.

The closer the engine runs to the thermostat opening temperature the better the cooling system is doing its job.
 
On my 78 fury, 318 factory AC car, I replaced the original wp in the low-40k mile range due to age and just preventive maintenance. This was back around 2011-12ish. Only did so because it was the original at over 30 years old.
That original was an 8 vane pump, parts store sold me a 6 vane. Ever since I put that 6 vane pump on I started having problems running hot. It never had with the 8 vane. I'd taken the radiator out a couple of times, and sent it in for flush/rodding out whatever it needed. It came back fine each time.
I ended up putting a flow kooler pump on and a 3 row champion radiator for good measure. It now runs cool. Almost too much so.
And I remember them saying that the 8 vane was the "with ac" version but couldn't get one at the time. Which agrees with what I took off originally.
 
Rat Bastid said:
You have to remember the longer the coolant is in the radiator, the longer it’s it’s in the block.

If you have 200 degree coolant coming out of the engine and an ambient temperature of 100 degrees you can only drop the coolant temperature maybe 20 degrees. Maybe.

There is some math to calculate all that out, but it requires me to use a scientific notation calculator and I’m not sure of all the variables. But a 20 degree drop is pretty close.

Now get the coolant coming out of the engine at 180 degrees. Because the coolant isn’t staying in the engine as long, it picks up less heat. Picking up less heat makes it easier for your 100 degree ambient temperature to get that 20 degrees out of it.

Of course, your thermostat opening point and the ability of the rest of the cooling system to do its job will determine how well the engine gets cooled.

The closer the engine runs to the thermostat opening temperature the better the cooling system is doing its job.
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I can back up part of that. My Duster has a 180 stat. Runs right about there.. in summer, it'll creep a Lil at a long light
 
Looking for more opinions here before I make a choice!
 
Of course, very little has been said here about air flow, which is the biggest part of the equation. If you’re not drawing enough air through the radiator, it doesn’t matter how fast or slow the water is flowing through. Maximizing your air flow is the biggest key to running at temp. The hood to radiator seal and the lower splash pan seal must be in place for the fan and shroud to pull enough air through the radiator. When you’re at a light, air flow is all on the fan, and without sealing the area behind the grille, it’s like sucking through a straw with a hole in it. Same goes for all those pusher fans, forcing air through the radiator with the fan blocking most of the airflow is about the least efficient way to get air through the radiator. There’s a reason the shroud is on the inside, and the fan is close to the outside of the shroud opening, it’s creating a vacuum that pulls air through the radiator. This also causes a vacuum effect behind the grille, and pulls more air through the radiator. It’s like a funnel effect, pour the liquid in the hole and the funnel will not back up, dump it in all at once and it backs up. The water pump regulates the flow, not too fast, not too slow, and the thermostat also does that same thing. The key is airflow.
 
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