Radiator-Temperature
Question for the 383 people.... did the inlet to the water pump move like on the SBs at some time?
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.
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.
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.
the 205 might be normal for what ever thermostat is in it, 90 deg day will shift the running temp up a bit
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 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???
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.
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
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.
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.
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.
in earlier (67 - 69) models the V8 shroud was the same for 273-383 (maybe even 440) slant 6 was the odd duck
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.
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
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.
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.