Water pump setup questions

[remytherat]

360 magnum, early LA front cover

New stock type 8 vane water pump

Pulley setup is overdriven around 1.3

4 row brass radiator

5 blade clutch fan

Standard type 180 thermostat

Lower hose does not appear to suck shut.

When hot, there is a 30-50 degree drop across the rad.


Runs fine in traffic and at low speeds, temp 195-200. Temp creeps up when on the freeway going over 65, and comes up to around 220 and stays there. Upon getting off or getting stuck in traffic it comes back down.

I’m wondering if my issue lies in using AC pulleys on the 8 vane pump, causing cavitation at high speeds. I know that the factory did not overdrive the 8 vane pump, for whatever reason. Would changing to a bigger pulley potentially increase the efficiency of my cooling system?

Alternatively, could it be that a stock type thermostat is not adequate for this setup? Would a high flow thermostat lower temps?

 

[Ricks70Duster340]

360 magnum, early LA front cover

New stock type 8 vane water pump

Pulley setup is overdriven around 1.3

4 row brass radiator

5 blade clutch fan

Standard type 180 thermostat

Lower hose does not appear to suck shut.

When hot, there is a 30-50 degree drop across the rad.


Runs fine in traffic and at low speeds, temp 195-200. Temp creeps up when on the freeway going over 65, and comes up to around 220 and stays there. Upon getting off or getting stuck in traffic it comes back down.

I’m wondering if my issue lies in using AC pulleys on the 8 vane pump, causing cavitation at high speeds. I know that the factory did not overdrive the 8 vane pump, for whatever reason. Would changing to a bigger pulley potentially increase the efficiency of my cooling system?

Alternatively, could it be that a stock type thermostat is not adequate for this setup? Would a high flow thermostat lower temps?

Are you running A/C?

 

[remytherat]

No AC

 

[Ricks70Duster340]

No AC

Your engine is making more power at highway speeds thus producing more heat. Without A/C inhibiting airflow via the condenser I would first suspect retarded timing or very lean condition at speed. What is your timing at say 3000? The other thing to look at is a high flow thermostat from Stewart Components. At higher speeds the flow needs to be high and the airflow through the radiator needs to be high too.

 

[remytherat]

What is your timing at say 3000?

35 Mech + 20 vacuum advance = 55 degrees

 

[Dana67Dart]

35 Mech + 20 vacuum advance = 55 degrees

because vac advance changes with throttle position and load. T in a vacuum gauge into the vac advance can line and read it at a given RPM while driving when the temp creeps up. Then you can determine what the advance really is at a given RPM by pumping up the vac can to the same vacuum and setting the engine at the RPM in question on the driveway, then check the total timing.

I have the same issue. except not as good in stop and go (no shroud).
stock 273, .95 ratio, I assume the non AC or HD cooling pump, under 65mph, 26" and 3.23. the temp is just left of straight up, 70 to 75 and it is just right of straight up. For reference straight up on my car is about 190

 

[Dana67Dart]

Runs fine in traffic and at low speeds, temp 195-200. Temp creeps up when on the freeway going over 65, and comes up to around 220 and stays there. Upon getting off or getting stuck in traffic it comes back down.

BTW you did not mention what the RPM is under the temp creep condition

 

[Dana67Dart]

Alternatively, could it be that a stock type thermostat is not adequate for this setup? Would a high flow thermostat lower temps?

I forgot to add, I went from a 180 standard thermostat to a 180 high flow and no change at all

 

[remytherat]

BTW you did not mention what the RPM is under the temp creep condition

3.21s on a 25” tire, so around 3000 and up

 

[Dana67Dart]

That's about what mine does.

 

[Bewy]

I would use a smaller pump pulley, not bigger, to increase the coolant flow rate.

 

[Dana67Dart]

Post some photos of your setup

 

[remytherat]

Problem solved

After a particularly hot drive, I had had enough, so I shotgunned the problem. It is now fixed but I don’t know exactly what the cause was.


The changes:
I reduced the water pump to crank ratio from 1.3:1 to 1.1. This is what I think solved it, getting me out of cavitation. I could be wrong, and I don’t know for sure.

I also put a new thermostat in it for good measure, though the old one seemed to work. Both standard type thermostats.

I also changed out my clutch fan for a fixed 7 blade. There is almost no way this made a difference at speed, but I felt like it was potentially good insurance if I was to overheat and then slow down into stop and go.


Took it out for some city driving and it stayed around the 187-190 range. Then drove across the city, 24 miles at 75 mph. Never went a degree over 190.

 

[Desoto291hemi]

I’m willing to bet that the pump ratio did the trick,,,,not all the other stuff .

Tommy

 

[Uncle Bob]

fixed 7 blade

You gotta watch those - there's a /6 one, 7 blades, looks up to the job, but no pitch so little airflow. Sounds like yours is OK though.

 

[junkyardhero]

You gotta watch those - there's a /6 one, 7 blades, looks up to the job, but no pitch so little airflow. Sounds like yours is OK though.

it's a V8 one from a 65 dart GT that sticky fingers McGee cadged from my pile of greasy parts inventory and absconded with

 

[remytherat]

And was replaced with a p̶i̶e̶c̶e̶ ̶o̶f̶ ̶s̶h̶i̶t̶ ̶c̶o̶v̶e̶r̶e̶d̶ ̶i̶n̶ ̶c̶o̶b̶w̶e̶b̶s̶ fan of equal or greater value

 

[Dana67Dart]

The factory parts books have pitch, diameter and number of blades and application.

 

[oldkimmer]

Glad u got it fixed. Kim

 

[CRUZE 418]

You'll never know, you changed more than one thing all at the same time.