Aluminum rad recommendations

Hey all,

I am considering moving to an aluminum rad to cool the GT down better. Can anyone recommend a good aluminum rad and shroud, or other combo unit that has worked well? It will need to cool my '67 GT…


I don’t recommend aluminum period. They don’t look proper or fit. You can’t use factory fan shrouds. I would go with a high quality two or three row copper factory style radiator. What engine is in the vehicle. We can go from there.

There is only one aluminum rad that is an exact fit but aluminum does not cool as well as brass / copper.

Anthems car is a GT so a 390. He has a pretty extensive post on cooling issues if you want to review it.
Anthem, Did it pan out to take it to the mechanic you had lined up? Just wondering if he was able to solve any of your problems. I know you mentioned you were not sure on the water pump at one point. A good brass/copper radiator is going to do a better job, and would keep things looking original.

My cooling issues have improved significantly. Highway or main drag city driving yields temps around 190-195. Still though, even on cool days like today, getting caught in traffic or too long at a light will send the temp up into the 210+ range. I installed a new 6-blade mechanical fan just today and it has had little to no effect. I have a good fan shroud and hood seal as well. I have a Mr. Gasket Hi-Flo stat (180*) and a brand new water pump, which did help some. The carb is set beautifully and the advanced timing is at 35* @ 2500 rpm. This also helped some. As I said, things have improved dramatically as I can now basically get in and drive pretty much at my leisure and not worry all too much, but as soon as the air flow goes down, the temp goes up…and higher than it should. I know an aluminum rad is not the magical solution. I just thought I would solicit some opinions and experiences.

This is the rad I have installed…

It would be very interesting if you had one you could borrow to use to see if it would make a difference after all you have done so far. Costly if had to buy one just to try it.

Well, GT’s come in small and big block versions. However, I will tell you as a learning curve that I would look for a few things.
The factory radiator is more than sufficient providing the core tubes aren’t plugged or reduced in size.
I am running a high efficiency factory three core radiator with a new core, a high flow Mr Gasket 180 degree thermostat, a factory thermostatic fan clutch, factory fan and fan shroud. I am in the Dallas area with temperatures at 100+ degrees late spring into early fall. The engine never exceeded the middle of the gauge. It doesn’t overheat. Even idling for an hour at 2000 rpm to seat a cam there was no issue.
Timing is critical. The aluminum radiator is not going to fix your dilemma outright. You also can’t run a fan shroud with aluminum aftermarket radiators and they don’t look like they belong. I have a relatively nasty 427 dual quad in my car.
If you have everything mentioned I would start looking at improper installation of the head gaskets. FE head gaskets say FRONT on them for a reason.
If they are installed incorrectly it will never run cool no matter what you do.
Instead of being a parts changer I would work to eliminate the possibilities first.
I wish I had more history on your situation. I could possibly offer more suggestions. However, this covers the more common ones. I just had to replace a 427 block because of an error in machine work from a so-called engine expert. Don’t assume your builder doesn’t have his head shoved in fourth point of contact when it comes to the FE.

I also failed to mention I am running an Edelbrock water pump. Your first mistake. Changing to a mechanical fan. If you have the original. I think it’s C6OE-F or G and a THERMOSTATIC fan clutch it works perfect. Use a Hayes 2711 if you do put an aftermarket in. It’s called out for a Corvette but it clears the three row with no issues. What is the overbore on the block. Did you go .060? Fill me in a bit more on your 390.


I just read all six pages of your other post. I noted a couple things. Do you have one belt driving everything? Have you changed the water pump?
I would look at the Edelbrock. There are no directional issues with FE’s other than the ultra rare reverse rotation engines.
You obviously don’t have one. I wouldn’t be concerned with 200 degrees either. I also noticed your fan looks a bit undersized. I recall them being about 18.25 inches in diameter. Is that an original fan?

This may give you a view of the fan and clearances.
Shelby right side engine compartment.jpg

Unlike Mustangs, all Cougars with the GT option were big blocks. S code 390s In '67 and in '68 either 390s or 428 CJs.

  • Phillip

I am accustomed to Mustangs. However, the GT and the GTA designation were used both on the Small and Big block applications. The difference being manual or automatic.

You are correct if refering to a Mustang. However things are different for Cougars. Any 1967 or 1968 Cougar ordered with the GT option received a big block, there are no small block GTs for those two years. Also the Cougar never received the GTA designation even if the car was equipped with an automatic transmission. A 67-68 Cougar GT could have a C6, 3 speed manual, or 4 speed manual transmission.

Randy Goodling
CCOA #95

The 6 blade aftermarket fans probably outperform an electric fan but they pale in comparison to the stock clutch fan with its seven blades.

I wasn’t questioning that fact that GT indicates a big block in a Cougar. I was stating that I am accustomed to Mustangs, which Is why I made the statement about the GT moniker on Cougars.

By the time they introduced the 428CJ in '68 they had a pretty good handle on cooling issues up to the 400 or so crank HP of the CJ. The viscous clutch and 7 blade fan with a 24" radiator and shroud works well. The big caveat is making sure the radiator flows well. I have had new radiators out of the box that did not flow well at all. Look in through the filler neck and see if there is solder at the top of the tubes that is partially blocking the tubes. One simple test is to verify that the radiator flows at least as much water as your garden hose can put out. If you disconnect the bottom hose, block the upper hose, and run a garden hose in the filler neck, you should not be able to over flow the filler neck. Look at the size of the hose running into and out of the radiator. Now compare it to the garden hose. That is a big clue to how much flow you need. Myths aside, the water pump can recirculate the coolant about 20 times per minute. That means a gallon every two seconds.

DeWitt’s makes their aluminum aftermarket radiators in aluminum here is the US just outside of Detroit. I have one in my '69 Cleveland powered Cougar. Stamped top tank and black paint makes it appear OEM-ish to the casual observer. Very please with the product, the quality, and a local maker (US and MI).

Brass actually cools better. This has been proven over and over again. The advantage is weight and cost. I’ll deal with the extra 15 pounds. Like Bill mentioned, the tubes where the solder is tends to corrode over time and restrict flow. His issue is NOT the radiator. I am leaning towards an inefficient water pump. There’s no need to change water pump pulleys either. Pick up an Edelbrock pump. Put the car back as it was.
I think that may clear up much of your issue.

Well it’s nearly hibernation time now anyway, so I think I’m just going to wrap it up for the season and give it some calm, rational thought over the winter. Seems to me at present however, that the case being made for a correct 7 blade clutch fan, as endorsed by Bill and Royce in this thread, is a good one indeed. That, and a step by step execution of the rad flow test as previously described by Bill, will quite likely be my first steps next Spring. I’m well ahead of where I was last year at this time, and I actually did get to enjoy some drive time this season, so all’s well as of today and that’s how I will close it out for now. Thanks to everyone on this thread for your engagement and good advice…