Big Block Cooling Help/Opinions

[co5j]

As always, backstory on Welcome Wagon, generational 70 Challenger has made it to our residence with some long standing cooling issues never addressed by my wifes dad (Diddy, 91yo). Apparently most of the gauges are useless, so ill be purchasing an aftermarket for the short term, drove it about 40 miles with outside temps in the upper 90s to get it to our house and the needle never moved from "C". Mechanical gauge best or is electric fine? Diddy has removed the thermostat (he's an old school drag racer), so I'll be replacing that. Currently a stock 26" radiator, not sure about cores, with shroud and stock clutch fan. What all do I need to be looking to change to do this justice? 440 6bbl setup with mild cam/mods, no AC, stock exhaust manifolds.

 

[pschlosser]

The cooling systems on these cars were pretty good. The 26-inch radiator providing the best cooling. The fan shroud and clutch fan offering even more cooling points.

Even during a heat wave, when the cooling system is working normally, the engines do not overheat unless you're hot-rodding significantly. And with moderate driving, no overheating at all.

So where to start looking for your overheating problem?

Core flow - check that radiator core and confirm its ability to cool, could be plugged cores.
Coolant flow - check that water pump
Timing - engine timing can contribute to engine heat, so make sure it's not too far advanced
Measure - measuring coolant temps can be as easy as a meat thermometer stuck into the filler neck of the radiator.
Clutch fan - check the clutch on the fan when warm and check airflow through radiator.
Engine flush - a longer engine flush, and even one where a freeze plug is removed to flush out casting sand, can improve cooling a great deal.

 

[Deathproofcuda]

I agree that stock 26" radiator with shroud and clutch fan should be adequate for your needs.

First thing to do is to actually confirm whether or not you have a cooling problem. If you don't have one already, buy a cheap IR thermometer, then take the car for a drive. After it warms up, pop the hood and take some temp readings on the radiator body and water pump housing.

 

[Xcudame]

And don't forget to put a 180°F thermostat back in it!

 

[co5j]

I think most of my assumptions that it could be cooled better, are lack of thermostat, gauge that was no help at all, and the fact that about 20 miles down the road it cut off every time i had to stop at a light/traffic without shifting to neutral and idling up. Just seemed hot.

 

[Xcudame]

A good flushing won't hurt anything, a new thermostat and getting a temporary temperature gauge plumped into the water pump housing will tell the tale if it's getting too hot. Right now, it definitely sounds like it is. You're on the right track!

 

[Deathproofcuda]

Cutting off seems more like a carb or timing issue than overheating. As @pschlosser said, timing will impact engine temps, although I'd say its more likely to run hot if too retarded. Factory timing specs were intentionally retarded to raise exhaust temps for cleaner emissions during that time. Car running too lean will also contribute to overheating.

 

[MoparCarGuy]

The correct thermostat ensures the coolant has time to shed its heat while in the radiator. This "dwell" time is critical.
Having a lower temp thermostat allows the coolant to circulate constantly with minimal or zero dwell time which hurts cooling system performance.
A quality 195°F thermostat (hi-flow) will aid coling for those in the southern US.

 

[co5j]

Most of the info i have shows a 195° stat, Xcudame suggests 180. Opinions? I bought a 195 but hey, $10. Im not even putting it in until i change the plugs n a new set of wires this weekend, old ones are burned all to **** laying across manifolds.

 

[co5j]

The correct thermostat ensures the coolant has time to shed its heat while in the radiator. This "dwell" time is critical.
Having a lower temp thermostat allows the coolant to circulate constantly with minimal or zero dwell time.
A quality 195°F thermostat (hi-flow) will aid coling for those in the southern US.
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Thank you, great info!!!