Keeping my 273 commando cooler during these record hot temperatures

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kbakewell

kbakewell

Kevin & Michael Bakewell
FABO Gold Member
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Location
Clearwater, FL
Recognizing from experience that Mopars always tend to run a bit on the hotter side, but also realizing we are experiencing record heat, especially here in Florida… Any thoughts on using coolant additives or non-water coolant to help keep the engine temperature down? Haven’t yet overheated this summer, but been close. Appreciate any thoughts and advice! I already have a high-performance dual electric fan, which has helped a lot.
 
Michael Brisebois said:
Do you have a radiator shroud?

They are always good for a 5 degree drop....or more
Click to expand...
Thanks Michael. I do indeed! I also have a high perf water pump which I’ve yet to install. Checking on the “easier” stuff first but probably need to get that done!
 
Honestly you can lower your t- stat but that will gain you little - bit some.
For me a clean radiator iand water jackets are the best. Even at 50-60years old the junk that accumulates in both amazes me. Sand like crap. Some say left over from casting the engine, some say due to antifreeze degrading. Not sure but I try to change coolant and flush about every 5 years.
Syleng1
 
Mopars don't tend to run hot. That's simply not true.

Make sure you're running a proper high flow thermostat. Very common mistake with AutoZone crap.

Beware the high performance pumps etc. they don't always do what you might think. Your car didn't have overheating problems from the factory even in the heat.

Make sure you're running enough advance. Us vacuum advance hooked up? Retarded timing will cause overheating.

Blown head gaskets will cause overheating bug time.

Get the basics sorted out first.
 
kbakewell said:
Recognizing from experience that Mopars always tend to run a bit on the hotter side, but also realizing we are experiencing record heat, especially here in Florida… Any thoughts on using coolant additives or non-water coolant to help keep the engine temperature down? Haven’t yet overheated this summer, but been close. Appreciate any thoughts and advice! I already have a high-performance dual electric fan, which has helped a lot.
Click to expand...
8 impeller water pump
1" larger diameter fan
How the initial timing?

Just a start.
 
For a start, get rid of the elec fans. Fit a clutch fan with a severe duty clutch. Mopar Perf used to sell a fan+clutch kit, P4120758; may still be available. Use a shroud.
Often with cooling, it is not one single thing that reduces temps. Rather, a number of things that make small changes, but when added together, drop the temp a significant amount.
Pump pulley should be 10-20% smaller in OD than crank pulley.
More here: www.stewartcomponents.com
 
Syleng1 said:
Honestly you can lower your t- stat but that will gain you little - bit some.
For me a clean radiator iand water jackets are the best. Even at 50-60years old the junk that accumulates in both amazes me. Sand like crap. Some say left over from casting the engine, some say due to antifreeze degrading. Not sure but I try to change coolant and flush about every 5 years.
Syleng1
Click to expand...
Thank you so much for the feedback. Definitely definitely agree with you about keeping the radiator clean. Actually upgraded the radiator so I have a nice clean one when I did a rebuild a few years back… Don’t seem to have any issues with flow whatsoever and the water is nice and clean.
 
While admittedly I'm not in the same climate as you my experience is that mopar stuff is significantly cooler running than gm or Ford stuff of the era.
So much so that in the 80's it was commonplace to put a 195 Stat and a restriction in the bypass on small block Chrysler in order to make any hear in the winter.

Every time I've seen a stock or mild small block Chrysler overheat it was a stuck thermostat or to small/plugged radiator.

Some of the early a bodies had a tiny rad and can't take much contamination before they affect cooling ability.
I'm also a big believer in clutch fans and shrouds. The biggest clutch fan you can fit,the biggest rad you can fit and a shroud that puts the fan blades roughly half in/out of the shroud is always a recipe for success.
 
A Fan shroud also helps I believe and they always seem to be missing on some of these cars.
 
Mean416 said:
Mopars don't tend to run hot. That's simply not true.

Make sure you're running a proper high flow thermostat. Very common mistake with AutoZone crap.

Beware the high performance pumps etc. they don't always do what you might think. Your car didn't have overheating problems from the factory even in the heat.

Make sure you're running enough advance. Us vacuum advance hooked up? Retarded timing will cause overheating.

Blown head gaskets will cause overheating bug time.

Get the basics sorted out first.
Click to expand...
Thank you for the input! My comment "Mopars tend to run hot" is based only on my lifelong ownership and experiences with them...starting with the '66 Plymouth Fury I my dad passed along to me as my first car :). My thermo is good, and appreciate the caution on the high-perf water pump. Maybe there's a reason I haven't yet put it on! Will double check my timing. Head gaskets fine as it's been professionally rebuilt. Again, thanks for your comments!
 
HankRearden said:
While admittedly I'm not in the same climate as you my experience is that mopar stuff is significantly cooler running than gm or Ford stuff of the era.
So much so that in the 80's it was commonplace to put a 195 Stat and a restriction in the bypass on small block Chrysler in order to make any hear in the winter.

Every time I've seen a stock or mild small block Chrysler overheat it was a stuck thermostat or to small/plugged radiator.

Some of the early a bodies had a tiny rad and can't take much contamination before they affect cooling ability.
I'm also a big believer in clutch fans and shrouds. The biggest clutch fan you can fit,the biggest rad you can fit and a shroud that puts the fan blades roughly half in/out of the shroud is always a recipe for success.
Click to expand...
Thank you for the feedback! Since I've owned only Mopars most of my life I wasn't aware of bigger issues with GM and Ford so guess I should be grateful! My thermo is good and I upgraded to a high capacity/perf radiator a few years back plus the dual electric fan. Thanks again!
 
Bewy said:
For a start, get rid of the elec fans. Fit a clutch fan with a severe duty clutch. Mopar Perf used to sell a fan+clutch kit, P4120758; may still be available. Use a shroud.
Often with cooling, it is not one single thing that reduces temps. Rather, a number of things that make small changes, but when added together, drop the temp a significant amount.
Pump pulley should be 10-20% smaller in OD than crank pulley.
More here: www.stewartcomponents.com
Click to expand...
Thank you!
 
First you could do a simple pressure check on your cooling system to make sure it is sound. Also even if it appears you have good flow through the radiator you could have damage to your water pump impeller vanes that you can't see that is affecting the volume of your pump output. Also your radiator cap. With the thermostat you want to pick the right one to keep the coolant in the radiator so it can do it's job and then open up and circulate the flow. And everything the other guys said. LOL
 
jeff alder said:
First you could do a simple pressure check on your cooling system to make sure it is sound. Also even if it appears you have good flow through the radiator you could have damage to your water pump impeller vanes that you can't see that is affecting the volume of your pump output. Also your radiator cap. With the thermostat you want to pick the right one to keep the coolant in the radiator so it can do it's job and then open up and circulate the flow. And everything the other guys said. LOL
Click to expand...
Thanks for the additional insight! Grateful for this forum!
 
Flowkooler is the only stock appearing pump with an impeller like this, they do move the water. It blew my silicone thermostat housing gasket out twice, then moved on to a Flashpower o-ringed housing. Other hi performance pumps are same ole same ole.

20220327_144205.jpg
 
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