440 overheating - Water pump?

[1971 Challenger]

Hey folks,
So I have a 71 Challenger, 440 BB, and unfortunately not a lot of information on the engine. I've been chasing an overheating issue since I got the car about 2 years ago. I did upgrade to EFI a while back but already had the problem. Recently, after a radiator/fan upgrade, I was on the pedal at high RPM on country roads and it climbed up to ~235, albeit it had sat beforehand in the sun for several hours. It moves up slower now overall but still climbs. Majority is at speed. I've read most of the posts so let me summarize where I'm at in no particular order without going over the entire past:
* Put in 26" Cold Case Radiator 2 row RAD-MOP754A
* 15 Inch 3,300 CFM Flex-A-Lite Black Magic Xtreme Series Electric Fan FLX-104367 8 blades with shroud
* Running 180 OEM thermostat; high flows failed and seem unreliable; fan come on at 190 as set in Sniper II.
* Running 15 degrees timing
* New hoses; none collapsed during operation
* EFI A/F ratio double-checked
* Inlet/outlet hoses and radiator core temperatures tested with IR gun and probe; They agree with my dash gauge.
* Fan has its own line to the battery; Alternator is at least 60A and is working fine.
* Serpentine pulley is fine.
* No fan on the condenser.
* 50/50 mixture. Coolant looks fine and at the proper level.

So I'm down to the water pump, I believe? Might I be getting cavitation? Not enough dwell time? Am I supposed to have a high flow water pump or standard? Is there any way to tell without pulling it? Any way to diagnose this component?
Let me know if I missed any troubleshooting aspects.

Thanks

 

[540HemiCuda]

"Dwell time" is a myth. Pull the thermostat and see what happens. And since you have an IR, check all areas of the radiator to make sure there aren't any hot areas that may indicate a blockage. Also, look below the thermostat at the bypass hole. How big is it? 1/4" is usually plenty. Mine are smaller than that.

Looks like lots of changes from stock, so it's hard to take anything for granted.

Does the shroud have any louvers so that air can flow through all of it at road speeds? I have seen some shrouds block air everywhere except where the fan is. And that's a fooler because road speed overheats are more often than not, a water flow issue.

A good rule of thumb is that if the temp climbs up at low vehicle speeds, it is usually an air flow issue. If the temp climbs, it is usually a water flow issue. Now, those are not hard and fast rules. But they have led me in the right direction MOST of the time.

Oh, and what is the drive ration between the crank and water pump pulleys as compared to the stock rations?

 

[CHLNGR]

Hey folks,
So I have a 71 Challenger, 440 BB, and unfortunately not a lot of information on the engine. I've been chasing an overheating issue since I got the car about 2 years ago. I did upgrade to EFI a while back but already had the problem. Recently, after a radiator/fan upgrade, I was on the pedal at high RPM on country roads and it climbed up to ~235, albeit it had sat beforehand in the sun for several hours. It moves up slower now overall but still climbs. Majority is at speed. I've read most of the posts so let me summarize where I'm at in no particular order without going over the entire past:
* Put in 26" Cold Case Radiator 2 row RAD-MOP754A
* 15 Inch 3,300 CFM Flex-A-Lite Black Magic Xtreme Series Electric Fan FLX-104367 8 blades with shroud
* Running 180 OEM thermostat; high flows failed and seem unreliable; fan come on at 190 as set in Sniper II.
* Running 15 degrees timing
* New hoses; none collapsed during operation
* EFI A/F ratio double-checked
* Inlet/outlet hoses and radiator core temperatures tested with IR gun and probe; They agree with my dash gauge.
* Fan has its own line to the battery; Alternator is at least 60A and is working fine.
* Serpentine pulley is fine.
* No fan on the condenser.
* 50/50 mixture. Coolant looks fine and at the proper level.

So I'm down to the water pump, I believe? Might I be getting cavitation? Not enough dwell time? Am I supposed to have a high flow water pump or standard? Is there any way to tell without pulling it? Any way to diagnose this component?
Let me know if I missed any troubleshooting aspects.

Thanks

View attachment 158623

I've been fighting this issue also. 1971 Challenger 440/AT ec.
First, spec for initial timing is 8 degrees. That could be it right there.
Second, when I converted to serpentine belts is when the issue began, as close as I remember. (I had shoulder surgery right in the middle of the process so I may not recall exactly) March Performance gave me an undersize crank pulley - 5-7/8" vs stock is 7 - 7-1/8". This means the water pump was rotating at 78% stock speed.
I've ordered a custom made crank pulley to the tune of 500 simolians. When it arrives I'll update you.
FYI, I've gone through the cooling system very thoroughly, about 3 times at this point. Re-cored radiator, new silicone hoses, (be sure you have a spring in the lower hose to guard against it collapsing) new electric fans with the expensive controller, FlowKooler hi-volume water pump, and so on. Oh - find a trans cooler that doesn't get in the way of your airflow. I got one for a Ford F150, it's 24" wide and only 4" high, so it's mounted at the bottom and doesn't slow the radiator air.

 

[sixpactogo]

I too suspect the serpentine system. There are many of them that are underdrive systems claiming better performance because of less horsepower usage.
Problem is, they underdrive everything. Alternator, water pump, power steering and AC if you have it. The manufacturers did a lot of research before coming up with the pulley sizes needed to do the best job. I had one on my 70 Challenger and noticed the discharge at idle, and the overheating at idle to be the biggest problem created by these pulleys. Once I got back to the correct sized pulleys, my problems went away. By the way, I didn't even have the 26" radiator. Mine was the 22" 3 row but I did have the thermo clutch 7 blade fan and shroud. Those serpentine kits are pretty and quiet but not always better.