I have a 472 hemi in a 67 R/T and the 3 row aluminum rad that cools fine in any temp while cruising down the road. Has a 6 blade steel fan,half a$$ shroud and stock mechanical water pump. No clutch fan, direct. 180 milodon stat. Car will not stay cool while in traffic for a reasonable amount of time. Once rolling it drops temp. Idles at 850 rpm.

I know this is a cooling issue associated with not enough air flow at idle. So I am considering a high flow pump and a 4 row aluminum radiator with shroud and electric fans as the "potential" solution.

I see a few on e-bay but wonder about the quality of the rad and fans. Except for Champion, the others have poor warranties but Champion does not offer a rad with fans and shroud.

Any other suggestions on how to remedy my heating issue and also a GOOD source for a rad/shroud that works for a 67 R/T. Core size must be 26 inch. Also I would like an adjustable temp controller for the fans as most of the ones turn the fans on at 180. I would rather see them on at 190-195 .

Thanks in advance to all. Thanks Moparts

I'd Look first at getting a good shroud. Your primary issue is inadequate airflow.

This can be confirmed with even a cheap fan zip tied to the radiator. If it cools down at idle when you turn the fan on, there you go.

On my 49 Dodge truck, I had to remove the factory motor driven fan because there wasn't enough clearance between the radiator and the water pump (you get that with putting a V8 and different chassis under old sheet metal).

My local Car Quest had a high CFM single 16" electric fan that has adjustable temp settings for the cooling speed settings. I bought the 16" fan because it fit the vary tight confines of the location it had to fit in and matched the height of my very small 4 core core Champion radiator. There is a temp range between the turn on and the turn off you can't adjust, but you can choose the high/low range of the operating temp. The fan comes in a kit with the fan, temp control thermostat, and a wiring kit. Its attached to the radiator with those radiator zip tie things and there are a few choices on how to mount the temp probe for the thermostat. This system has been on the truck for a couple of summers now and seems to be working well. You will need to make a shroud for it to work on your radiator, or there could be larger diameter fans (or a dual fan) system available. My point is, adjustable temp electric fan kits are out there. When mine kicks on, you can watch the temp drop on the temp gauge. It only runs a minute or two when the coolant temp hits your high temp range, and shuts off when it reaches the low temp setting. I have mine is wired through the ignition switch so it only runs when the motor runs, but it can be set up to come on ( and turns off) when ever the temp limits are hit.


With that said, making a very good fan shroud for your existing system may actually solve your cooling system problems. You really need to pull as much air through your radiator at idle speed as you can, and your current half azz shroud isn't doing the job. If the good shroud doesn't solve your issue, you can then simply buy the adjustable electric fan to replace your existing fan size.

https://board.moparts.org/ubbthreads/ubbthreads.php/topics/2485313/1.html

you can read hear on the mercedes cooling fan and the controller created for it.
it cools quite well.

By half @$$ shroud I mean the fan blades are in half way in/out as recommended but there are some gaps on the bottom of the shroud where the shroud meets the rad. I do not think a shroud is the answer completely. And the aluminums with fan/shroud are not that expensive to try.

I'm wondering if a smaller pump pulley to speed up the air/water flow would be a solution

Had a similar deal with a pretty stout 512" RB in a Duster; it would hit 200 or so in traffic.
Added a shroud to its aluminum radiator, and a smaller pump pulley.
Never got over 180 after that.
Also: prior owner had an electric pusher fan - which blocks airflow - and I removed it.

Most agree that air flow is the issue. Having been in this position before, I'll offer a suggestion that has worked for me; I go to a pick-a-part yard and pull a fan from an 80s Dodge pick up. It is too large in diameter to fit in the shroud. But, it's aluminum so it's easy to cut down, is lighter than the steel fan you have now, and it's balance isn't hurt much with the trimming.

Those fans move a LOT of air. More blades and more pitch to boot so it gets a clutch due to the additional drag. I have used this on several Mopars with no down side. Currently I have one on the 540 Hemi in my Cuda and it still has the original re-cored radiator with a good shroud.

And, if it matters, this route is cheap.

i'm certain a lot of people have the same or similar problem that the OP has; i do for one. so, what smaller pulley would be recommended?

Got a pic of this?

I'm not good at posting pics, but I'll try.

Here's one I already had. Such as it is. When I get a chance, I'll try to get a bit better shot or two.

Here's a pretty thorough dive into cooling systems.


https://www.enginebasics.com/Engine%20Basics%20Root%20Folder/Engine%20Cooling.html

I would try a 160 stat first and go from there

All a thermostat does is set the minimum temperature. It will do nothing for overheating.

Generally speaking, and by design intent, a thermostat does regulate minimum coolant temp.
But if the cooling system has enough capacity & flow capability, a cooler thermostat can bring operating temps down.
I did that on my Dually, and it definitely runs cooler.
That said, it also has an added ATF cooler and its factory oil cooler.

I forgot to add in a previous reply that water rejects heat a bit better than anti-freeze.
If the OP's climate allows it, I'd also drop the anti-freeze ratio to 25%.
At the track of course, no anti-freeze.

I have the opposite problem in my stockish 67 383 Coronet. Runs hot on highway and cools off as soon as I slow down.

Sounds like you need a thermostat
I've seen that in the past living in the Mojave desert in the summertime in and driving in the daylight

needs more radiator (or current one rodded out)

or you have an airflow blockage at higher speeds, or you have a colapsing lower hose at speed.