[Formulajones]

Don't necessarily need a shroud. With a good fan and close enough to the radiator that deal seems to work. Our nomad never had any type of shroud from the factory. Yet we've had a pretty high strung and strong running 327 in that thing since the 70's, and just a typical 4 core stock looking replacement radiator from Desert Cooler, and a direct drive 7 blade GM fan. Drove it daily for years, that engine will run 180 degrees all the time no matter what the outside temps were or how hard you pushed it. It helps that the radiator really isn't any wider than the fan itself too.

Funny today the aftermarket actually makes a shroud for the tri-5's now because people feel they need one I guess, but it never had one originally and from my experience, doesn't need it.

Get into these situations where the engines are so far back from the radiator like dad's 69 GTO, or the fact that they use a radiator that is 28" wide and a fan can't cover that space, then I start to see the need for a shroud.

In your case Dick, as you can see in your photos, the 64-65 A-body radiator really isn't that wide, and is about the same size as a tri-5 chevy radiator, and same down flow design. A good 18-19" fan damn near covers it, lol.

[KEN CROCIE]

Dick B: I ordered my 64 EXACTLY the same as yours. Still have the 19" clutch fan, 4 core radiator, no shroud ,as delivered. Now has a modified 455 H-O with A/C. No cooling problems. Can't figure why later cars have issues. But they do!

[Steve C.]

Installing An Improved Pontiac Cooling System – Cool Winds

https://www.hotrod.com/articles/hppp...ooling-system/


.

[64speed]

When I got my Tempest it had a non stock shroud on it of dubious origin and the gm 19 inch fan. Although it was just a worn out 326 no matter what you did to it it would never go over 180. The radiator sprung a leak and already looked horrible so I ordered a champion. Same result never went over 180. Now that I have this big honking 467 I ordered a cold case HO radiator but without the electric fans. I bought a smaller derale 17 inch fan and a factory shroud and will hope for the best. Just a little Tidbit though, if you’re looking at Summit for water pumps don’t buy the Milodon. I ordered it cause it was middle of the road price wise. I got it and it had GMB stamped in the front of it. I got on Rockauto and the GMB aluminum water pump was 1/4 what I paid for the Milodon. I ordered the GMB and confirmed they were the exact same so I called Summit and told them someone had box swapped them and I wanted another Milodon pump sent out. Got the new Milodon. Guess what, it’s a GMB. They are just reboxxing them and marking them up. I sent them back to Summit and kept the one from Rockauto. Aluminum pump with cast iron impeller. We will see how it cools

[chrisp]

Originally Posted by 64speed

When I got my Tempest it had a non stock shroud on it of dubious origin and the gm 19 inch fan. Although it was just a worn out 326 no matter what you did to it it would never go over 180. The radiator sprung a leak and already looked horrible so I ordered a champion. Same result never went over 180. Now that I have this big honking 467 I ordered a cold case HO radiator but without the electric fans. I bought a smaller derale 17 inch fan and a factory shroud and will hope for the best. Just a little Tidbit though, if you’re looking at Summit for water pumps don’t buy the Milodon. I ordered it cause it was middle of the road price wise. I got it and it had GMB stamped in the front of it. I got on Rockauto and the GMB aluminum water pump was 1/4 what I paid for the Milodon. I ordered the GMB and confirmed they were the exact same so I called Summit and told them someone had box swapped them and I wanted another Milodon pump sent out. Got the new Milodon. Guess what, it’s a GMB. They are just reboxxing them and marking them up. I sent them back to Summit and kept the one from Rockauto. Aluminum pump with cast iron impeller. We will see how it cools

GMB uses a small cast impeller not full vane , was the milodon the same small cast impeller ?

[Tom Vaught]

Originally Posted by Dick Boneske

I've seen flex fans, electric fans, non-clutch steel fans, shrouds, huge radiators, etc. on cars that overheat. I can't explain why ours never have a problem.

My first guess would be "PCP" (a Poor Choice of Parts), on cars that overheat, and then a lack of knowledge on how to actually tune the parts on the engine. Poor Carb Tuning, Poor Timing Control, Race Car parts but not actually a Race Car (PCP).

Tom V.

[Firebob]

My old 4 core brass in the bird went bad or got clogged or whatever and I was going to go aftermarket alum. Then a buddy said he had a fairly new 4 core that he had had made with "waffled" tubes so I put it in. Last year I got caught in terrible cruise line n Reno and before I pulled over my temp gauge said 243. Over last winter I installed the Taurua 2 speed elec controlled by the sniper. These last few days have been the hottest I've had it in so far. 100 deg ambient temps( running up to 204), yesterday commuting home in stop and go and slow roll at 80 deg amb( 206). Still running the same brass rad. Im not too worried until it breaks over 210 but I'd rather it not get there. We haven't hit the full heat of summer here yet so I'm thinking a new rad is probably in my future. At that point I may decide to go back and try out the other fan options again and see what works best. Just would be nice not to have to worry about it anymore.

[dataway]

Assuming a radiator in good shape, generally if a car over heats in traffic and not on the highway, it's an air flow problem, not a radiator problem.

If the car doesn't over heat on the highway it means the radiator is capable of removing the necessary amount of heat. If it can't remove the necessary amount of heat at idle or in traffic it's most likely not enough air flow .... or in some cases not enough low rpm water flow.

[Formulajones]

Originally Posted by Tom Vaught

My first guess would be "PCP" (a Poor Choice of Parts), on cars that overheat, and then a lack of knowledge on how to actually tune the parts on the engine. Poor Carb Tuning, Poor Timing Control, Race Car parts but not actually a Race Car (PCP).

Tom V.

And that's really the gist of it Tom. It has nothing to do with a particular body style or older stuff working better than newer stuff. When these cars were new, does anyone really recall any of these cars having any serious heat issues? I don't.

Fast forward 50 years, these cars have been through the ringer with aftermarket parts floating all over the place, and backyard mechanics with their fingers in everything, overheating on any car can be a multitude of reasons, non of which are the cars fault.

Funny story, we attend Goodguys twice a year in Scottsdale. March and November. Those dates usually have mid 80's for temps in that part of Arizona. What amazes me at the end of the day when 2,000 cars try to file out of that place and you get sort of a log jamb at times. The amount of cars that have to pull out of line because they are overheating and pushing antifreeze just flat boggles my mind. Literally dozens and dozens of them. I just idle along in line and shake my head in disbelief. Here we have cars that people have 10's of thousands, and even 6 figure digit numbers invested, and they can't idle on an 85 degree day without puking?? Sad. I feel sorry for them when the temps hit 115 degrees, lol. If you can't cut it on an 85 degree day in Arizona, you're going to be in serious trouble.

[Formulajones]

Originally Posted by Firebob

My old 4 core brass in the bird went bad or got clogged or whatever and I was going to go aftermarket alum. Then a buddy said he had a fairly new 4 core that he had had made with "waffled" tubes so I put it in. Last year I got caught in terrible cruise line n Reno and before I pulled over my temp gauge said 243. Over last winter I installed the Taurua 2 speed elec controlled by the sniper. These last few days have been the hottest I've had it in so far. 100 deg ambient temps( running up to 204), yesterday commuting home in stop and go and slow roll at 80 deg amb( 206). Still running the same brass rad. Im not too worried until it breaks over 210 but I'd rather it not get there. We haven't hit the full heat of summer here yet so I'm thinking a new rad is probably in my future. At that point I may decide to go back and try out the other fan options again and see what works best. Just would be nice not to have to worry about it anymore.

I've been in the Reno (Hot August Nights) traffic. Gotta have a car up to snuff that's for sure. We haven't reached our hottest here yet either, but since dad's is actually running "cold" right now in 85 degree temps cruising and idling, I'm pretty confident it will be fine when ambient reaches over 100 in the next month. Very happy considering the size of the engine and the power it makes.

[RocktimusPryme]

Speaking of Ford fans, there has been novels written about the success stories of putting junkyard Mark VIII, Taurus, and the dual Sable/Cougar fans with enormous success at a low price. Well now if you put those model numbers in the google machine you will find those fans reproduced as stock replacement by companies like Dorman. Does anyone know if those replacement models pull a similar amount of air compared to their factory forefathers?

Again we all know that the factory fans work, but the youngest of those parts are nearly 2 decades old now. Electric motors do wear out and die.

[torqhead]

Originally Posted by JLMounce

I'm pretty curious about that flex-a-lite 295 setup myself. I currently have the factory brass HD radiator on my 69 bird with a flex fan. I don't overheat, but I specifically stay away from stop and go traffic.

Like others here on the highway it runs about 195 on a 90 degree day. That's at 3400rpm cruise. Cruising around the city at around 30-45 mph the temp drops to about 190, but as soon as you start sitting and idling temps creep and I've seen as high as 215 idling to get into a car show.

It seams like I possibly have two issues at play. 1. the factory rad probably needs a re-core (or a new rad) and 2. I have airflow or coolant flow issues at idle/low speed. The car is originally an AC car so it does have the lower and upper baffling, all of which is installed.

Wondering if the flex-a-lite 295 may help cool a bit better at low speed.

Jason, I had referred Larry to the flex-a-lite. It's worked well for me for many years. If you want to see it close up, you know how to find me...

[71 T/A]

In my 69 GTO with A/C, I've run a Griffin 1.25" tube radiator since 2005 with no issues.
With the a/c on a 90-degree day, car will run 160 on the highway and 170 on the street. I use the Hayden severe duty clutch fan and factory 19" fan.

[george kujanski]

My combo: '67 GTO, '74 455 stock stuff. When I got the car it had PCP (Tom V's Poor Choice of Parts).... 3 row radiator from something unknown. Puked after heat soaking and hard to start.

Clearanced the pump plate..BIG difference went from about 1/4" to about .050". Temp would still rise on a hot day (85 or greater in traffic, high humidity). Added a shroud, somewhat better.

Finally got around to replacing the known wrong 3 row radiator narrow tank with a Cold Case (proper tank size like a OEM 4 row) and now it stays at thermostat setting.

The Cold Case design certainly improves the cooling, as expected, but it's also sized as a OEM radiator would be for a 400+ sized engine. Adding a shroud, (I feel it's mandatory for a large V8) is the proper thing to do also, I can't imagine some OEM versions that don't have a shroud for the V8's. To me, that just moves the underhood air around at idle, I guess it's good enuf at idle since the waste heat production is a lot less.

George

[Steve C.]

Two articles that maybe of interest.....

How to Design And Build A High-Performance Cooling System

https://www.hotrod.com/articles/ccrp...ooling-system/


Fan Shrouds - A Critical Cooling System Component

https://www.speedwaymotors.com/the-t...omponent/28863

Many street-car overheating problems occur at low vehicle speeds because of reduced airflow through the radiator. The best way to combat that is with a fan shroud designed to pull air from the entire radiator.


.

[Firebob]

One thing I did notice last year. On my way home it was about mid 80s and I got stuck in a line of cars about 2 miles long getting through a stoplight. I was sure after overheating in Reno there was no way I was going to make it. When the temp started to creep up I got out and popped the hood about 6-8 inches. It let enough of the underhood heat out that the temp stayed under control. I was actually shocked that it worked because I was in traffic for quite some time moving now and then when the light changed and let a few cars through. Kind of makes me think that some sort of hot air evac system from the engine comp might go a long way to keeping things from getting ugly. They had air extractors on the original 69 Trans ams. I'm not sure how effective they were but those guys didn't usually do things for nothing.

[64speed]

Originally Posted by chrisp

GMB uses a small cast impeller not full vane , was the milodon the same small cast impeller ?

Exact same pump

[gtokid]

Originally Posted by 64speed

Exact same pump

+1 on this. The milidon has gmb even stamped on it


Sent from my iPhone using Tapatalk

[64speed]

I do need to mention that GMB makes two separate pumps and it’s the nicer of the two but 40 dollars is ok. 130 not so much

[Cliff R]

"My first guess would be "PCP" (a Poor Choice of Parts), on cars that overheat, and then a lack of knowledge on how to actually tune the parts on the engine. Poor Carb Tuning, Poor Timing Control, Race Car parts but not actually a Race Car (PCP)."

+2

The key to running cool and not needing a butt-ton of aftermarket parts starts with the engine build and well chosen parts. I have ZERO issues in the area of running hot, overheating, detonation, etc with our engines. Matter of fact we have the opposite problem, they are difficult to get up to temp, especially when it starts getting cool/cold outside.

From what I've seen one common denominator with running hot, even with pretty "mild" set-ups is quench distance. The tighter you squeeze one of these engines the LESS heat it transfers to the coolant. Combine that will well selected compression ratios, camshaft events, and very close control of timing/fuel curves and you'll find your new engine will not "creep" up past the thermostat set point with steady cruising (common problem with Pontiac engines) or getting stuck in traffic when it's really hot outside.

We also run hotter thermostats in our engines as thermal efficiency is your friend with these things. It's important for the oil temps to get hot enough to boil the water vapors out of them to reduce sludge and "froth" formation. Not uncommon at all to see "modern" engines with stat's in them well over 200 degrees. Coincidentally I worked on a friends 2010 Jeep Cherokee recently. It was not running well and started to suck down a LOT of fuel. Did a scan and noticed the engine temps were down around 150 degrees. Replaced the stat (pretty sure it was 207 degrees) and it instantly corrected all the issues and fuel mileage cam right back to where it should be.........Cliff