Radiator-Temperature

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Gr8polarbear

Gr8polarbear

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I am going to try to keep this short.

I really don't want this to turn into a bickering match about - aluminum vs copper, thermostat vs no thermostat temperature or degree of thermostat to run have read way to much of it.

1972 Scamp 383, 727 trans w/remote cooler, 3.91 gears, electric fuel pump.

To start, bought the car last summer and the dash temp gauge worked, sort of. Normal warm days the gauge would read what i am guessing was about 150. During cooler days it would barely come off of cold which leads me to believe there is no thermostat. Gauge on dash stopped working so installed a phantom temp gauge in it. The instructions tell you to put the ground as close to the sensor as possible, i did not do this due to not wanting extra wires under the hood, but is a good ground. This gauge during same situation on warm day was reading 180. Which was kind of was expected due to dash gauges not being the most accurate.

Forward to last week. 90 outside and went for a drive after about a half hour the temp got up to 205. This is not horrible but i am used to a more efficient cooling system in all the cars i have had in the past. So within about 10-15 degrees of the thermostat. Which would be under under 200 no mater what. Drove 55 mph for about 10 min and temp did not go down. Normally am used to getting up to speed and engine cool off some. Stopped at the store for a few minutes came back out car started fine but had rough idle.

Next day started up the car and let it idle up to temp 180. Broke out the thermal imaging camera and started looking at temps. Temperature of parts of the radiator, upper and lower hose were all the same from cold all the way to 180. So yeah probably no thermostat or is stuck open to partially open. Once it got up to temp coolant started to rise in the radiator and when rev it up coolant level dropped while rpms where up. So seems normal. All the way up to this point i saw no movement in the radiator as far as flow.

I plan on changing the water pump to flowkooler and high flow thermostat have not decided which one yet. What are you guys running for a thermostat? (Brand)

The car has radiator 2949045 1969 C-BODY 26 318 BOTH HTR WITH X51
No idea what x51 is. So here is my concerns on this. First the current radiator is built for 318 not a mild build 383. Inlet and outlet are both on driver side. I have read that unless the radiator is separated in the middle to make a row over and row back this is not to efficient due to the liquid going strait down. I am guessing the factory is not this way. Also someone changed the radiator from a 22 to a 26 at some point and i am guessing made more holes to do so. I am looking for a radiator that will drop right in to where the holes are on the current radiator. Does anyone know what i should be looking for to basically get the same mounting as what is in it. I dont know what cars had what kind of mounting.

I have two options, buy new or recore. Called the place near me and they said a recore would be 600-1000. 600 i am not to worried about but 1000 i am trying to stay away from.

I drive the car mainly on the street.
No it does not have a shroud, i know this would help but with different engine and radiator than the car came with, i have not dug into that yet.
I would like to not remove the radiator until i get all the parts.

Taking thermal image from the front radiator for the most part looks the same. From inside the bay you can see some spots that look cooler. I dont know how much the spinning fan plays a part in that.

Last summer i drove the car for 2 hrs straight at 55 mph and did not puke so that tells me there are not major problems but i didnt know the real temp due to it being the dash gauge but again stayed about the 150 mark.

What is everyone's thoughts?

FLIR_20230817_091834_291.jpg
 
You tell us what we can't talk about and then ask us precisely what you say we can't talk about. So what can we talk about?

I can tell you if the coolant coming out of the radiator is the same temp as going in (that's what you said) then the radiator is not doing its job, thermostat or no. Was I allowed to say that?
 
I am just saying that everytime one of the things i requested not to mention comes up there seems to be nothing but everyone going back and forth for many pages about who is right forgetting about the original question.

But yes thank you for your comment this is the kind of answer i am looking for.
 
High flow thermostat and high flow water pump. If you do one without the other (especially the high flow water pump with a standard thermostat), you're not doing anything. The high flow thermostat by itself can actually make a difference. In MY personal experience and opinion, any REAL high performance build benefits from running as cool as possible. I like the 160 high flow thermostat because it opens soonest and doesn't allow the water in the engine to get as hot as quick. It's all about getting the water OUT of the block AS SOON AS POSSIBLE before it starts getting really hot. The quicker you get it in and out of the radiator, the better. Those who say you need to slow the water down so it stays in the radiator longer don't have a clue how a heat exchanger works. If the water is as cool as you can get it going IN and the radiator is doing its job, it will be even cooler coming out and that's the name of the game. Just tune the engine to run well at the lower temps and you'll be fine. This is simply my opinion backed up by my experience of doing just what I've outlined for many years. It works. I wouldn't mind seeing what you're using to take those infra red pictures with.
 
Gr8polarbear said:
Thank you for your comment. Yes i plan on using a high flow 160 thermostat. Engine seems to run really well around this temp. Which one do you recommend?

This is what i use for the images. It is cheaper and works well. Flir One Gen 3 hooked to an android tablet.

FLIR ONE Gen 3 Professional Thermal Camera for iOS and Android Smart Phones | Teledyne FLIR
Click to expand...
Stewart Components. They are the best. To quote our buddy rat bastid, "they flow like Niagara Falls" and he's dead right.
 
Gr8polarbear said:
Are Stewart Components and Stewart-Warner the say thing?
Click to expand...
They are not the same company. I believe (others may chime in) that SW divested years ago and Stewart Components picked up on the cooling system products. Their EMP-301 looks exactly like the OE style thermostats that came with our engines way back.
 
RustyRatRod said:
High flow thermostat and high flow water pump. If you do one without the other (especially the high flow water pump with a standard thermostat), you're not doing anything. The high flow thermostat by itself can actually make a difference. In MY personal experience and opinion, any REAL high performance build benefits from running as cool as possible. I like the 160 high flow thermostat because it opens soonest and doesn't allow the water in the engine to get as hot as quick. It's all about getting the water OUT of the block AS SOON AS POSSIBLE before it starts getting really hot. The quicker you get it in and out of the radiator, the better. Those who say you need to slow the water down so it stays in the radiator longer don't have a clue how a heat exchanger works. If the water is as cool as you can get it going IN and the radiator is doing its job, it will be even cooler coming out and that's the name of the game. Just tune the engine to run well at the lower temps and you'll be fine. This is simply my opinion backed up by my experience of doing just what I've outlined for many years. It works. I wouldn't mind seeing what you're using to take those infra red pictures with.
Click to expand...

As many of you`all know , I had a fair amount of trouble keeping my 505'' wedge cool to start with , after a bunch of experimentaion , I have it acceptable , (thanks to a few guys on here) recommendations and my experimenting .

It runs around 195ish to 205 on hot days , a little cooler in cooler weather .
So rrr , ur saying a 160 degree thermostat will help even more ?
Have a 180 walkershaw in it now ...
 
Pic says it all .
There's partial to total blockage of the tubes in the middle, the hot coolant is doing it's best to pass whatever coolant it can down thru the few tubes on the sides. If you drag your knuckles across the rad, the center tubes would be cool compared to the outer tubes.
Looking at the pic, you can see why I have always asked for temps from the actual rad fittings, not the hose, see the temp difference of the hose, cooler, false temp.
Get the rad rodded out .
The cooling system should have the capacity to keep coolant at thermostat temp, if it can't, and it goes higher, something is deficient, you are beyond capacity to keep it at thermostat temp, and any " work" will cause overheating.
Ideally your thermostat is never totally open at operating temp, it modulates, and needs to be able to open further when "work" causes the engine to create more heat, - or temp will continue to rise till it pukes .
Sorry OP .
Good luck
 
Last edited:
Question for the 383 people.... did the inlet to the water pump move like on the SBs at some time?


Gr8polarbear said:
To start, bought the car last summer and the dash temp gauge worked, sort of. Normal warm days the gauge would read what i am guessing was about 150. During cooler days it would barely come off of cold which leads me to believe there is no thermostat. Gauge on dash stopped working so installed a phantom temp gauge in it. The instructions tell you to put the ground as close to the sensor as possible, i did not do this due to not wanting extra wires under the hood, but is a good ground. This gauge during same situation on warm day was reading 180. Which was kind of was expected due to dash gauges not being the most accurate.
Click to expand...
The way to "Calibrate" your dash temp guage is to measure the temp at the base of the temp sender and then look at the temp guage. My stock 67 dart with 273 2bbl on cool / cold days the needle sits just past the low end of the normal scale, on hotter days it sits a couple needle widths past that, and on really HOT days it will sit at about streight up.

I have measured the temp sender in all settings and low end of normal range is in the 180 range
a few needles width to the right of that 195
and straight up in the 205 range

all nothing to worry about.

Gr8polarbear said:
Forward to last week. 90 outside and went for a drive after about a half hour the temp got up to 205. This is not horrible but i am used to a more efficient cooling system in all the cars i have had in the past. So within about 10-15 degrees of the thermostat. Which would be under under 200 no mater what. Drove 55 mph for about 10 min and temp did not go down. Normally am used to getting up to speed and engine cool off some. Stopped at the store for a few minutes came back out car started fine but had rough idle.
Click to expand...
the 205 might be normal for what ever thermostat is in it, 90 deg day will shift the running temp up a bit

Gr8polarbear said:
Next day started up the car and let it idle up to temp 180. Broke out the thermal imaging camera and started looking at temps. Temperature of parts of the radiator, upper and lower hose were all the same from cold all the way to 180. So yeah probably no thermostat or is stuck open to partially open. Once it got up to temp coolant started to rise in the radiator and when rev it up coolant level dropped while rpms where up. So seems normal. All the way up to this point i saw no movement in the radiator as far as flow.
Click to expand...
I also have a thermal imaging camera and have done the same as you did. What I noticed is the upper rad hose never got 100% engine temp parts of it were cooler. I suspect the coolant flow was not hitting the hose uniformly or the fan was cooling the hose somewhat.

I keep an inch air gap in my radiator so no need for an overflow but with the cap off I see similar to what you describe.

There will not be any flow in the rad till the thermostat opens enough to allow flow through the rad. all the needed flow goes through the BY-Pass hose till then.

Your thermal image of the back side of the rad MIGHT show that there are clogged tubes OR its just the air flow from the fan cooling the rad tubes???

Gr8polarbear said:
The car has radiator 2949045 1969 C-BODY 26 318 BOTH HTR WITH X51
No idea what x51 is. So here is my concerns on this. First the current radiator is built for 318 not a mild build 383. Inlet and outlet are both on driver side. I have read that unless the radiator is separated in the middle to make a row over and row back this is not to efficient due to the liquid going strait down. I am guessing the factory is not this way. Also someone changed the radiator from a 22 to a 26 at some point and i am guessing made more holes to do so. I am looking for a radiator that will drop right in to where the holes are on the current radiator. Does anyone know what i should be looking for to basically get the same mounting as what is in it. I dont know what cars had what kind of mounting.
Click to expand...


On earlier Pre 70 SBs the inlet and outlet are on the same side (Drivers) later they moved the outlet (bottom) from the rad to the Pass side.

The earlier rads have a baffle inside the top tank to direct the inlet flow toward the passenger side of the Rad

having the inlet and outlet on opposite sides is most likely more efficient but the 67-69 GTS 383s ran that way with no issues.

as for 26 vs 22 inch rad. UNLESS your core support opening has been cut out to match the 26" rad you are not gaining much n the way of cooling as the extra 4 inches are blocked by the core support.

US Radiator has some good info about cores and rows and AL vs Copper Brass

Gr8polarbear said:
I have two options, buy new or recore. Called the place near me and they said a recore would be 600-1000. 600 i am not to worried about but 1000 i am trying to stay away from.
Click to expand...

3rd option is to rod out the existing rad. I had that done to a HP/AC 67 Dart Radiator and it was in the 4-500 range.


Gr8polarbear said:
I drive the car mainly on the street.
No it does not have a shroud, i know this would help but with different engine and radiator than the car came with, i have not dug into that yet.
I would like to not remove the radiator until i get all the parts.
Click to expand...
in earlier (67 - 69) models the V8 shroud was the same for 273-383 (maybe even 440) slant 6 was the odd duck

Gr8polarbear said:
Taking thermal image from the front radiator for the most part looks the same. From inside the bay you can see some spots that look cooler. I dont know how much the spinning fan plays a part in that.
Click to expand...

Your thermal image of the back side of the rad MIGHT show that there are clogged tubes OR its just the air flow from the fan cooling the rad tubes??? if you block the fromt of the radiator with card board you should see a more uniform thermal image if the fan is causing some localized cooling

Gr8polarbear said:
Last summer i drove the car for 2 hrs straight at 55 mph and did not puke so that tells me there are not major problems but i didnt know the real temp due to it being the dash gauge but again stayed about the 150 mark.
Click to expand...

you don't know what temp it was running, I suspect it was at or near thermostat temp. if it was cool out.








NOW for CONTRIVERSIAL conversation...

If you use a 160 thermostat (which the FSM specifically states is not a good idea) then your engine is not getting up to design temp for bearing clearances etc.

Copper Brass is my preferred material of choice (search "my engine overheats" and see how many start with "I just installed an Aluminum whiz bang radiator" and how many start with "I just installed a stock copper brass radiator")

A factory style shroud will help at low speeds and idle but does nothing at road speeds. If you have a shroud that is parallel to the rad core it will restrict air flow at speed, the closer to the core the more it will restrict.

I have nothing against electric fans IF they are designed for the application. MOST of the electric fans are on shrouds that block 25 to 50 percent of the core area. Do the math, measure the area of the openings and the area of the Rad see for yourself

Thermostatic mechanical fan clutches DO NOT increase cooling efficiency. They only allow for the use of an aggressive fan pitch and reduce some noise when the rad is cool (depending on clutch design and settings) (so technically having one allows for some cooling efficiency when married to the correct fan)

Most likely you could use a 67-69 Dart 383 cooling setup as your starting point, from the water pump to the thermostat, pulleys, fan shroud etc. I would look to the CAP / AC / HD cooling / Trailer Towing options for parts.

Good luck to you.
 
Dana67Dart said:
Your thermal image of the back side of the rad MIGHT show that there are clogged
Your thermal image of the back side of the rad MIGHT show that there are clogged tubes OR its just the air flow from the fan cooling the rad tubes??? if you block the fromt of the radiator with card board you should see a more uniform thermal image if the fan is causing some localized coolin
Click to expand...

Wrong .

If the tubes weren't blocked,- I would expect the center tubes to be hot at the top, and getting progressively cooler towards the bottom, - if they were flowing any hot coolant, - wouldn't you ?
 
Last edited:
famous bob said:
As many of you`all know , I had a fair amount of trouble keeping my 505'' wedge cool to start with , after a bunch of experimentaion , I have it acceptable , (thanks to a few guys on here) recommendations and my experimenting .

It runs around 195ish to 205 on hot days , a little cooler in cooler weather .
So rrr , ur saying a 160 degree thermostat will help even more ?
Have a 180 walkershaw in it now ...
Click to expand...
Very possibly, yes. High flow 160.
 
inertia said:
Pic says it all .
There's partial to total blockage of the tubes in the middle, the hot coolant is doing it's best to pass whatever coolant it can down thru the few tubes on the sides. If you drag your knuckles across the rad, the center tubes would be cool compared to the outer tubes.
Looking at the pic, you can see why I have always asked for temps from the actual rad fittings, not the hose, see the temp difference of the hose, cooler, false temp.
Get the rad rodded out .
The cooling system should have the capacity to keep coolant at thermostat temp, if it can't, and it goes higher, something is deficient, you are beyond capacity to keep it at thermostat temp, and any " work" will cause overheating.
Ideally you thermostat is never totally open at operating temp, it modulates, and needs to be able to open further when "work" causes the engine to create more heat, - or temp will continue to rise till it pukes .
Sorry OP .
Good luck
Click to expand...
You might be right, BUT I think what we're seeing is air flow blockage. Look closely right in the center. That's the outline of the hood latch frame. Also, I believe the hotter temps on the sides are the sides of the radiator support instead of the core opening. They higher temp colors correspond perfectly with those areas.
 
Dana67Dart said:
Question for the 383 people.... did the inlet to the water pump move like on the SBs at some time?



The way to "Calibrate" your dash temp guage is to measure the temp at the base of the temp sender and then look at the temp guage. My stock 67 dart with 273 2bbl on cool / cold days the needle sits just past the low end of the normal scale, on hotter days it sits a couple needle widths past that, and on really HOT days it will sit at about streight up.

I have measured the temp sender in all settings and low end of normal range is in the 180 range
a few needles width to the right of that 195
and straight up in the 205 range

all nothing to worry about.


the 205 might be normal for what ever thermostat is in it, 90 deg day will shift the running temp up a bit


I also have a thermal imaging camera and have done the same as you did. What I noticed is the upper rad hose never got 100% engine temp parts of it were cooler. I suspect the coolant flow was not hitting the hose uniformly or the fan was cooling the hose somewhat.

I keep an inch air gap in my radiator so no need for an overflow but with the cap off I see similar to what you describe.

There will not be any flow in the rad till the thermostat opens enough to allow flow through the rad. all the needed flow goes through the BY-Pass hose till then.

Your thermal image of the back side of the rad MIGHT show that there are clogged tubes OR its just the air flow from the fan cooling the rad tubes???




On earlier Pre 70 SBs the inlet and outlet are on the same side (Drivers) later they moved the outlet (bottom) from the rad to the Pass side.

The earlier rads have a baffle inside the top tank to direct the inlet flow toward the passenger side of the Rad

having the inlet and outlet on opposite sides is most likely more efficient but the 67-69 GTS 383s ran that way with no issues.

as for 26 vs 22 inch rad. UNLESS your core support opening has been cut out to match the 26" rad you are not gaining much n the way of cooling as the extra 4 inches are blocked by the core support.

US Radiator has some good info about cores and rows and AL vs Copper Brass



3rd option is to rod out the existing rad. I had that done to a HP/AC 67 Dart Radiator and it was in the 4-500 range.



in earlier (67 - 69) models the V8 shroud was the same for 273-383 (maybe even 440) slant 6 was the odd duck



Your thermal image of the back side of the rad MIGHT show that there are clogged tubes OR its just the air flow from the fan cooling the rad tubes??? if you block the fromt of the radiator with card board you should see a more uniform thermal image if the fan is causing some localized cooling



you don't know what temp it was running, I suspect it was at or near thermostat temp. if it was cool out.








NOW for CONTRIVERSIAL conversation...

If you use a 160 thermostat (which the FSM specifically states is not a good idea) then your engine is not getting up to design temp for bearing clearances etc.

Copper Brass is my preferred material of choice (search "my engine overheats" and see how many start with "I just installed an Aluminum whiz bang radiator" and how many start with "I just installed a stock copper brass radiator")

A factory style shroud will help at low speeds and idle but does nothing at road speeds. If you have a shroud that is parallel to the rad core it will restrict air flow at speed, the closer to the core the more it will restrict.

I have nothing against electric fans IF they are designed for the application. MOST of the electric fans are on shrouds that block 25 to 50 percent of the core area. Do the math, measure the area of the openings and the area of the Rad see for yourself

Thermostatic mechanical fan clutches DO NOT increase cooling efficiency. They only allow for the use of an aggressive fan pitch and reduce some noise when the rad is cool (depending on clutch design and settings) (so technically having one allows for some cooling efficiency when married to the correct fan)

Most likely you could use a 67-69 Dart 383 cooling setup as your starting point, from the water pump to the thermostat, pulleys, fan shroud etc. I would look to the CAP / AC / HD cooling / Trailer Towing options for parts.

Good luck to you.
Click to expand...
The FSM is also talking about stone stock engines. I'll just stop the argument right there.
 
OP.
Could you post a similar pic from the front please?
If possibly, could you go shoot a similar pic from either front or back of any other vehicles you have access to, see if you can reach a conclusion.
A post here might be nice, thank-you.
 
Last edited:
Gr8polarbear said:
I am going to try to keep this short.

I really don't want this to turn into a bickering match about - aluminum vs copper, thermostat vs no thermostat temperature or degree of thermostat to run have read way to much of it.

1972 Scamp 383, 727 trans w/remote cooler, 3.91 gears, electric fuel pump.

To start, bought the car last summer and the dash temp gauge worked, sort of. Normal warm days the gauge would read what i am guessing was about 150. During cooler days it would barely come off of cold which leads me to believe there is no thermostat. Gauge on dash stopped working so installed a phantom temp gauge in it. The instructions tell you to put the ground as close to the sensor as possible, i did not do this due to not wanting extra wires under the hood, but is a good ground. This gauge during same situation on warm day was reading 180. Which was kind of was expected due to dash gauges not being the most accurate.

Forward to last week. 90 outside and went for a drive after about a half hour the temp got up to 205. This is not horrible but i am used to a more efficient cooling system in all the cars i have had in the past. So within about 10-15 degrees of the thermostat. Which would be under under 200 no mater what. Drove 55 mph for about 10 min and temp did not go down. Normally am used to getting up to speed and engine cool off some. Stopped at the store for a few minutes came back out car started fine but had rough idle.

Next day started up the car and let it idle up to temp 180. Broke out the thermal imaging camera and started looking at temps. Temperature of parts of the radiator, upper and lower hose were all the same from cold all the way to 180. So yeah probably no thermostat or is stuck open to partially open. Once it got up to temp coolant started to rise in the radiator and when rev it up coolant level dropped while rpms where up. So seems normal. All the way up to this point i saw no movement in the radiator as far as flow.

I plan on changing the water pump to flowkooler and high flow thermostat have not decided which one yet. What are you guys running for a thermostat? (Brand)

The car has radiator 2949045 1969 C-BODY 26 318 BOTH HTR WITH X51
No idea what x51 is. So here is my concerns on this. First the current radiator is built for 318 not a mild build 383. Inlet and outlet are both on driver side. I have read that unless the radiator is separated in the middle to make a row over and row back this is not to efficient due to the liquid going strait down. I am guessing the factory is not this way. Also someone changed the radiator from a 22 to a 26 at some point and i am guessing made more holes to do so. I am looking for a radiator that will drop right in to where the holes are on the current radiator. Does anyone know what i should be looking for to basically get the same mounting as what is in it. I dont know what cars had what kind of mounting.

I have two options, buy new or recore. Called the place near me and they said a recore would be 600-1000. 600 i am not to worried about but 1000 i am trying to stay away from.

I drive the car mainly on the street.
No it does not have a shroud, i know this would help but with different engine and radiator than the car came with, i have not dug into that yet.
I would like to not remove the radiator until i get all the parts.

Taking thermal image from the front radiator for the most part looks the same. From inside the bay you can see some spots that look cooler. I dont know how much the spinning fan plays a part in that.

Last summer i drove the car for 2 hrs straight at 55 mph and did not puke so that tells me there are not major problems but i didnt know the real temp due to it being the dash gauge but again stayed about the 150 mark.

What is everyone's thoughts?

View attachment 1716133435
Click to expand...

Looks to me like most of the tubes in that radiator are restricted except for the far left end.
Hot coolant is entering at the top drivers side and flowing across the top, the down through mostly those few tubes and back across the bottom to the outlet.
That explains both hoses being about the same temperature.

Your description of events and your heat image results both confirm it.
 
TrailBeast said:
Looks to me like most of the tubes in that radiator are restricted except for the far left end
Click to expand...
I think you hit the nail on the head.

This is my 67 273 2bbl, OEM HD/AC rad core.

Screenshot_20230826-135850.png


Screenshot_20230826-140021.png



Screenshot_20230826-140145.png


Screenshot_20230826-140244.png



Note the uniformity.

This rad was rodded out 2 years ago

The shop believed it was an original core
 
Again, note the hose is not the place to shoot the temps.

Good work Dana, great pix, I coulda used those a decade + ago.
OP good job on original pic, thnx
Cheers.
 
Last edited:
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