if you have a 185 degree thermostat, it will not be completely open until around 195 degrees so.
it seems your cooling system is working well as is. if it doesn't exceed 200 degrees, i wouldn't worry about it.
if you have any coolant mix at all and a 16lb cap, i wouldn't worry about 210-220.
the more heat, the more efficient the engine will be, gas mileage and horsepower.
just my opinion, your mileage will vary.

180 degree stat. While sitting still at an idle, if I lock both fans on, I can get it down to 183 which is what I expect.
I would like to keep it in the 180's at highway speed, too.

Gas mileage is not a concern (single digits) with a 272@.050 cam, 451 ci, 3.91 gears and no overdrive

Yes, I agree it's not "really" overheating, but since I run on pump gas (not even 93 octane here in most places), I want to keep it cooler than 200.
And I don't want the fans to stay on while driving on the highway... extra load, wear on the motors, etc.

You might do better buying a proper rad and some high flow fans and also putting your pickup for your fans for your fans in a better place if this dont pan out.

I run a dual pass rad, HV dual spal fans and have one fan on the Temp sending unit and the other on a manual toggle since I hardly use it but can over ride all with another.

Cruising with a 5200 vert and 4:30 gears the one fan shuts down in a few minutes at over 45 mph using only cruising air to cool on a big inch small block thats 1/2 filled.

I would try what grizzly said and if there is an improvement you might consider a bit better shroud and fans more purpose made for your needs vs boneyard parts.

My t stat deal is a 165 that I have in the intake cross over, so fan comes on then and never goes over 185-190 on the temp gauge.

I agree with others on here suggesting that your fan and shroud combination is becoming a restriction to air flow at highway speeds.

I assume that those fan openings are 11", so your 2x11" fan setup has just 190 square inches (2 x 95 square inches) of opening on your 468 square inch radiator. Compare that to the 314 square inches that a 20" stock clutch fan shroud opening would be.

Notice the diameter of that huge Mercedes fan... it looks like it could be close to a 20" fan opening which would have an open area similar to a stock fan shroud.

As others have suggested, you need to open up some holes in your fan shroud to let the air flow through at speed. Right now, the same amount of air is trying to flow through an area that is just 60% of what it would be with a stock fan shroud setup.

Do you just have a out of the box t stat or do you add a little bypass help with 3 1/8 holes on the outer edges?

X

That's really helpful.

Out of the box Milodon high-flow stat...

X

The 6 1/4" counts the thickness of the radiator, so if you have that distance to the backside of the support, you might be able to get it in there.

I don't need or appreciate "jabs" and why would you bother stating the obvious except to be a smart-ass, or concern troll?
That doesn't help solve my cooling problem.
You are equally blindered that it has to be airflow. Yes, you may be right!

I am not the only person who's running these fans on a big-block! Where do you think I got the idea to use them in the first place... they are compact, high cfm and inexpensive. All important characteristics.

As a physician I am well aware that colleagues (AND patients) can fixate on one aspect of a case, to the detriment of the patient. Sometimes we even change our diagnosis if the initial one is incorrect! And if I'm wrong I will be the first to admit it, right here - would you?

X

I would look for a small town-to-town 2 lane with minimal to no stop signs and minimal to no traffic to test on.

A 45 or 50mph kind of a road should do it.

Pick out some places to stop and work on the car or let it cool if you have to.

Drive there. Then take the fan and shroud assembly off and put it in the trunk. Then test. Obviously abort/stop if there's a problem.

If it seems to prove the idea the shroud is blocking airflow, then you have choices.
Try to create flaps (rubber, plastic, other) for air to travel through your existing shroud at speed that the fans can suck closed at low speeds, or try to shroud just one fan,
or go back to the drawing board.

When I ran the HHR fan on my GTX I tried a similar temp switch to activate it, and had a similar high speed issue.
I realized the time I could potentially put into getting flaps and so on set up to my liking, and wasn't into doing that.
Eventually I sold all that and went back to a belt driven fan.
I'm sure you can get it to work if you spend enough time playing with it.

That's the first thing I tell people, as putting a spring in my lower hose cured my overheating problems on the highway.

If you put an air dam under the Radiator core support it will create a low pressure on the engine side of the radiator & it will help keep things cool when driving. lots of newer cars have them that have electric fans, I have one like this off a 3rd gen Camaro that I cut down on my 68 Charger. my 512 cid with COLD AC runs 185ish ALL DAY long in 108 deg Southeast Texas heat

First I have 2 miles of dirt/gravel (35 mph max), and then all the 55 mph two-lane I can use Roads for testing are not an issue.


Unfortunately there is not room to do that - I just tried (in the garage with everything cold)! I have to remove the radiator/fan as an assembly, then take it out, put it back in, refill, etc. Now I've got the fans loose and the coolant is draining, I'm going to pull the rad and then replace the WP with the Flowkooler high-flow unit anyway.


I agree, and that is my plan (to prove or disprove the airflow being the problem which some people are 100% convinced of)
There is already about 1.5" at the bottom and 1" at the top of the core which are not covered by the Contour shroud, too.
It's likely to be a trade between not enough cooling at idle and not enough airflow at speed.



Funny you should mention that. I initially had bought an HHR fan, but discovered it wouldn't quite fit between the WP and the radiator. I'd considered using it as a pusher but the blades are canted the wrong way and it makes a lousy pusher anyway.

There is not room (the front edges of the fan blades will be way too close to the core) for a fan clutch which doesn't engage until enough hot air comes through the radiator, and that's hotter than I want. Could just stay with the setup I have.

There IS room (just) for a flex fan direct driven. Keeping in mind that they also flex forward at high speed (DAMHIK)

As you say, IF I spend enough time playing with it. Thanks for the helpful suggestions!

My '72 Dart already has one (sort of)... they call it a "front valance" I believe.

LOL, yea OK, you ask for help, do your research

That was really helpful too

Have you actually read any of my posts?

OK, some more data for those who think I'm not actively trying to research the cooling too...

I managed to get the fans out by only draining the coolant and removing the top hose. So I refilled it and went for a ride (78F and humid at the present).

A very strange phenomenon, maybe someone can tell me why: Warmed it up a bit to 160 on the gauge, started driving, temp went to 183 and t-stat opened as expected. Fast drop to 165 as the cold coolant in the radiator hit the engine, then gradually back up to 182. I drove a couple of miles at 30 mph and it stayed on 183. Thought I had my answer for sure (airflow obstruction). But wait, there's more...

So I turned around in the driveway (10 sec. max) and while I was doing that, the temp popped up to 190. Started down the road at 30 mph again... and it would not come down below 188 in the next mile.

Made another 3-pt turn down the road, and it rose to 198. Another mile, would not come down below 196, so I drove back to the garage and shut it down! Went up to around 215 due to accumulated engine heat. I put the garage fan on the radiator and it's dropping slowly (the electric fans would normally kick on and off a few times).

The gauge does not seem to be sticky, so I have to assume for now that the temperature readings are real.

How on earth can it be operating steadily at one temp, but "bump" it a little while idling/stopped and it won't come back down? This is outside my area of experience and I've never seen this on any other car I've driven in the last 40 years!

And I know it's not obstruction of the airflow by the shroud since the radiator core is sitting there wide-open...