360 running hot…very hot

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It's likely it is a dual pass radiator. Look for weld marks where the divider is welded in approximately half way up the tank.
 
That type of radiator is called a double pass ....it circulates fluid to the other tank through internal baffles. I understand how it looks but that's not how it functions.
 
aside from the sender being possibly no good, that isn’t a shroud really at all And it appears to be a lazy flow radiator that the inlet and outlet are on the same side. Even some oem big block rads are lazy in that the lower hose is on the drivers side and the upper is kind of in the middle. Ideally a cross flow would be much better like the champion cc526 rad. 526

I know your radiator may be new, but it also too small, you should have a 22” one in there with a top and bottom tank. Get rid of the side tank jobby you have in there now. The fan is also too small. The shroud you have is blade guard, won’t do anything to help cooling.

I think you should start Over with the right stuff and you will have zero problems moving forward
 
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This is the answer I needed. Thank you 4mulas. Cross flow, plus a real shroud, plus a bigger fan. Thank you!! I'll report back with results. Thanks to all....i learned a lot in a short period of time!! This forum is awesome.
 
Sdriche said:
This is the answer I needed. Thank you 4mulas. Cross flow, plus a real shroud, plus a bigger fan. Thank you!! I'll report back with results. Thanks to all....i learned a lot in a short period of time!! This forum is awesome.
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What you have now is a cross flow radiator. It might be too small but if it cools the car sufficiently at speed it should be able too cool it at idlle and low speed. The difference is mostly you have less airflow and less coolant flow at low speed and idle. I would focus on air flow first.
Better shroud and bigger fan. Might be all you need. Depending on what you have now a pulley ratio that turns the Waterpump and fan at a faster speed may also help. If you were having problems keeping it cool at speed as well as low speed and idle I would be more inclined to replace the radiator. This is assuming all things mechanically and tune up is correct. Just my opinion others here have good ideas as well.
 
92b said:
What you have now is a cross flow radiator. It might be too small but if it cools the car sufficiently at speed it should be able too cool it at idlle and low speed. The difference is mostly you have less airflow and less coolant flow at low speed and idle. I would focus on air flow first.
Better shroud and bigger fan. Might be all you need. Depending on what you have now a pulley ratio that turns the Waterpump and fan at a faster speed may also help. If you were having problems keeping it cool at speed as well as low speed and idle I would be more inclined to replace the radiator. This is assuming all things mechanically and tune up is correct. Just my opinion others here have good ideas as well.
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I'll start with airflow/fan/shroud and continue to the radiator after testing. The car is in tune. I'll check advance but if it overheats at idle right after start up not sure advance matters. Much appreciated. I have a path fwd thanks to everyone.
 
Sdriche said:
I'll start with airflow/fan/shroud and continue to the radiator after testing. The car is in tune. I'll check advance but if it overheats at idle right after start up not sure advance matters. Much appreciated. I have a path fwd thanks to everyone.
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Overheating at idle can be curb idle is set too lean and/or initial timing is too retarded.
 
The rad has to shed min 30*(6 cyl) 50+* is ideal/better.
If it's not, figure out why.
Go shoot the top/bottom rad fittings on any other vehicle while hot !
 
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If you have any kind of Cam that's bigger than about .480/228 at .050 you're going to need initial timing that's about 18° or more..or it'll get hot at low speed/sub full advance.
so check your timing, reset it if you have to ...and take a test drive to see if it starts to get warm again at idle low RPM speeds. If the timing is good then look at the fan size.
 
I had that problem once and found the water pump impeller had moved out on the shaft and was not close enough to the water pump body. This left about 1/2 gap from water pump housing and impeller which made it not circulate the water correctly. Had already replaced the radiator and thermostat without any progress pulled pump off and found this problem. Replace pump and fixed problem.
 
Not sure if this is causing the issue. But which water pump is on your 360?

6 vein = AC pump
8 vein = Non AC pump
AC water pump pulley = Smaller diameter
Non AC water pump pulley = Larger diameter
 
That dual pass radiator is killing you. Those things are worthless.

Do some research on those radiators and flow and you’ll figure it out.

I posted some links in another thread you should read.
 
AJ/FormS said:
IMO, this is real simple;
If your rad is dropping the temp 30degrees, from top to bottom, then your cooling system is working exactly right. Go to Note-5
If only 20*, it could be better but as soon as the car is moving even just 10 mph, the temp should be dropping. There are several things you can do to make it better, most of which have already been mentioned.
BUT
the first thing to do is make sure that your Idle/slow-speed timing is NOT retarded. See note-1
This puts heat into the cylinder walls and into the exhaust ports; where it is picked up by the circulating water.
The temperature of the headers within the first four inches of the flanges, at idle should be less than 450*F. see Note-2
After you get all that bugged out, and you still cannot get to a 25/30* temperature drop across the rad at idle with the vehicle stopped, and if this is a recent engine-build, then see note-5

Happy HotRodding

Note-1
Your Idle timing, with an automatic and the stock 360 2bbl cam should be around 8>10*. The more cam you put into her, the more Idle-timing it will want. Some of the FABO guys are running 18 to 25 degrees. But the more timing you run, the more closed the transfer slots in the carb will be, which leads to a throttle tip-in sag, and she may bang on the N/P to in-gear shift. The mechanical timing should begin advancing about 100>200 rpm above idle, and should hit 25 to 28 degrees by 2800rpm, and then slowly creep all-in by 3400 +/- 200
Your vacuum advance MUST be working.

Note-2
Closer to 400 or even 350 is better. If it's hotter than 450, I would suspect that the exhaust gasses are exiting the chambers still on fire.
Here's an easy test; just pull some timing in, without regard to how much, then re-adjust the idle speed back to "normal". Just keep repeating this until adding timing produces no additional rpm. Now read the header temperatures, and watch the temp gauge. Put the timing back after the test. See Note-3

Note-3
Caveat; if the carb's low-speed circuit is exceptionally rich, and you have a long overlap-period cam, and the headers are working really well, then the headers at too slow an idle can draw A/F mixture right across the top of the pistons and out the exhaust ports, and into the headers. Under the right circumstances, this raw mixture can ignite and artificially increase the header temperature. see Note-4

Note 4
If you have a metering-rod carb, make sure the rods are staying DOWN at Idle. If a PV you shouldn't have trouble unless the diaphragm is ruptured.

Note-5
Ima betting your ring-gaps are too tight and or, not enough skirt clearance.
Here's the easy test; Make sure your battery is in good shape. Then run the temp up to ~210 by IR gun, then shut her off. Wait 5 minutes than crank her up. If she fails to crank, or cranks real slow/with much difficulty, STOP! the pistons or the rings have locked up, and the engine needs to come apart.

Note-6
If the engine is hopped up, it behooves you to, at your earliest convenience, to rig up a fresh cold-air intake system. Hot underhood air is less dense and will appear to the carb as being at altitude. Wiki says that you are at 259 feet. Your engine can make good power there on fresh air.

Note-7
I should mention that;
with your type of shroud,
at idle and vehicle stopped,
the fan can actually draw hot air backwards at the corners, from under the hood to around the corner, and back thru the rad. The paper-test will prove it. Once the car gets moving, ram air will prevent that.

Note-8
forget about electric fans at least until you get your heat-issues solved.
Once you do get your heating solved, if it was me, I would just install a Thermostatic clutch on the biggest fan I can find, installed into a full-coverage shroud. Let the clutch take care of business.
Oh wait,
I already did that, with killer results!
In your case, I would also recommend a hi-flow pump which is just an 8-vane pump with an anti-cavitation plate installed, and usually, a HD bearing to support that big-boy fan/clutch. I have had excellent results with a Milodon.
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Very nice, AJ. Not like your usual rambling. I'm impressed.
 
Oldmanmopar said:
Here is what I see wrong. The upper hose is on the same side as the lower hose on a cross feed radiator. Someone move one of the hose nipples on the radiator. That will make it run very hot.
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You always look at things through a different lens. Good catch!
 
Hey neighbor, I had basically the same set up you have there in the same car. I bought a Cold Case Rad and repop factory plastic shroud. So far so good even in town.
 
Sdriche said:
it was originally a slat 6 car. Its possible the fan was moved over to the 360....i dont have history on it sorry.
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When I first swapped my '67 from a slant six to a 340 I continued using the 1970s era slant six replacement radiator. They are smaller but not so much smaller that they can't handle idling, especially if the engine hasn't been driven hard.
Sdriche said:
This is the answer I needed. Thank you 4mulas. Cross flow, plus a real shroud, plus a bigger fan. Thank you!! I'll report back with results. Thanks to all....i learned a lot in a short period of time!! This forum is awesome.
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The factory info is a good reference for the what will do the job.
For 68 and 69 most v-8 got a 22" core radiator although 2bbl engines without A/C and without trailer or max cooling did get 19"
upload_2022-2-19_19-48-2-png.png

Downflow may work better with the vented radiator caps which kept the system at atmospheric pressure most of the time.
Cross flow has some theoretical cooling advantages but I think in most cases, including this one, its a matter of what physically works best.

Fan is very important. By '68 all for v-8 were 18" diameter.
Differences were in the size and number blades.
1680376211102-png.png

(Yellow outline was for someone looking for A/C equipped application)

Additional catch with a later engine in a pre 1970 model.
The later water pump is longer and its inlet points to the right instead of the left.

Transmission cooler in the bottom tank of the radiator is helpful in cold weather and often sufficient.
If pulling a trailer or racing, then an addtional trans cooler is helpful. I have one from transgo on my car about the size of yours.
 
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George Jets said:
Here is an interesting thought.

I see you have the aluminum passenger side exit water pump, and yet your top hose coming from the thermostat is also on the passenger side of your Cross Flow radiator.

Like it is circulating the coolant through the passenger side radiator tank and back into the engine, without it circulating through the main part of the radiator.

Here is a picture of a '76 D100 truck radiator and shroud with the upper hose on the driver's side allowing the coolant to circulate through the full radiator.

View attachment 1716088985

☆☆☆☆☆
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Oldmanmopar said:
Here is what I see wrong. The upper hose is on the same side as the lower hose on a cross feed radiator. Someone move one of the hose nipples on the radiator. That will make it run very hot.
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Professor Fate said:
Good catch, guys! :thumbsup:
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That picture shows a reflection of the top hose on the chrome fan guard. See picture below.

Hot 360.jpg
 
Professor Fate said:
Yup, and previous picture showed the late model aluminum water pump on the engine, which is a passenger side inlet.
That puts both the inlet and outlet of the radiator on the passenger side.
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It's likely a dual pass radiator like 92b said above. The OP made it sound like he bought it new, so he can verify. If it's not a dual pass, that'd be an awfully bad f-up for a 'new' radiator.
 
mopowers said:
It's likely a dual pass radiator like 92b said above. The OP made it sound like he bought it new, so he can verify. If it's not a dual pass, that'd be an awfully bad f-up for a 'new' radiator.
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True- but since the brand/origin is unknown, I would assume nothing, especially with the proliferation of cheap offshore radiators. It's easy enough to verify- just snake a piece of wire/coathanger/welding rod straight down the inside of the tank from the top radiator inlet and see if you hit a baffle.
 
The radiator is a double pass radiator. I put a proper fan shroud on which covers the entire radiator. The blades do sit inside vs half out so may need to modify. Initial test is that I can feel WAY more air being sucked in. I let it idle and it didn't get past 190. Will drive this week to confirm but seeing improvement. I have a derale 17" fan arriving Monday
 
Professor Fate said:
True- but since the brand/origin is unknown, I would assume nothing, especially with the proliferation of cheap offshore radiators. It's easy enough to verify- just snake a piece of wire/coathanger/welding rod straight down the inside of the tank from the top radiator inlet and see if you hit a baffle.
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You got that right!
 
Sdriche said:
The radiator is a double pass radiator. I put a proper fan shroud on which covers the entire radiator. The blades do sit inside vs half out so may need to modify. Initial test is that I can feel WAY more air being sucked in. I let it idle and it didn't get past 190. Will drive this week to confirm but seeing improvement. I have a derale 17" fan arriving Monday
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Great! Maybe you got it licked! I hope so!
 
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