[71 T/A]

Has it been determined or a consensus been reached about which type of fan cools better? I have always run clutch fans but I live in a hot climate (South Florida) and wonder if dual electric fans blowing a lot of air would work better especially at idle for my 69 GTO in traffic.

[Tom Vaught]

My Opinion is:

Key Words are IDLE and South Florida.

Clutch fans, imo, typically are not that good at sensing ambient temps, just over temps under the hood. By then the engine is really hot.

Cooling Fans used on lots of vehicles (Like high end Lincolns, Cadillacs, Aston martins, etc.)

If you have the electrical system and radiator area to handle them, in my mind the way to go in Florida. Along with a manual over-ride switch
if in a parade.

Tom V.

[geeteeohguy]

As a guy who runs stock fans on my old cars (clutch and flex type), I have to agree with Tom 100%. For slow speeds, prolonged idling, at hot temps, nothing beats an electric fan or fans. They turn very high RPM, and pull a TON of cooling air through the radiator core of a stationary vehicle. Mechanical fans pull very little air at low engine speeds by comparison.

[android 211]

My 72 TA with 455 HO, automatic trans and a/c would sit in traffic in Miami in gear with the a/c on and stay at 180 the whole time.
It had a factory clutch fan and a four core brass radiator out of an Eldorado. It fit without modification. Blocking air leaks is important. The shroud in the car when I got it
had a big chunk missing off one corner. I replaced it with a junkyard acquisition that had no missing pieces and saw an improvement in
engine temps. I recall once being outside the car on a hot day, the engine was idling. I hear a click noise and a 'whoose' and a newspaper blowing by got sucked into the grill.
That was the clutch engaging the fan.

[Will]

A properly functioning 7-blade clutch fan with a shroud will suck an elephant through the grill at idle.

Never had any problems at idle with my Formula, and that's the setup it came with from the factory.

[Tom Vaught]

Originally Posted by android 211

My 72 TA with 455 HO, automatic trans and a/c would sit in traffic in Miami in gear with the a/c on and stay at 180 the whole time.
It had a factory clutch fan and a four core brass radiator out of an Eldorado. It fit without modification. Blocking air leaks is important. The shroud in the car when I got it
had a big chunk missing off one corner. I replaced it with a junkyard acquisition that had no missing pieces and saw an improvement in
engine temps. I recall once being outside the car on a hot day, the engine was idling. I hear a click noise and a 'whoose' and a newspaper blowing by got sucked into the grill.
That was the clutch engaging the fan.

Maybe he can find a "four core brass radiator out of an Eldorado" too.

Yep, I ran a Superior Radiator 4 core RACE radiator with a factory 7 blade fan and it cooled fine. He asked about cooling fans, stock vs electric, not changing whole cooling systems. Bet android's cooling system with the 455 HO engine and a/c was not the normal firebird cooling package either.

Tom V.

[71 T/A]

Currently, I run a Griffin 1.25" tube radiator. It cools great on the highway, about 165-170 but at a long stop, temps start creeping up and won't stop until car starts moving. Then temps go back down to 170 or less.

[Cliff R]

I tried electric fans quite a few years ago, and really liked that deal.....except that when racing it pulled down the battery and worked the charging system pretty hard. Nice way to get rid of some heat but the alternator isn't getting used enough on race days to keep the battery at full charge when running the fans.

Great on the street and no issues with it anyplace.......Cliff

[Formulajones]

I've run a dual electric fan setup on one of our daily drivers in the past. No complaints with it. I think what I liked the most is how it cleans up the engine bay with much more room to work in front of the engine.

Honestly though, I have no issues with the clutch fans and idling in traffic, even in the desert heat here in AZ. I use the Griffin exact fit radiator line with dual row 1 1/2" tubing. Even my 600 HP engine will idle all day in the heat, stock fan shroud and clutch fan and never see anything over 175. With the AC blowing it would run 185-ish. That radiator is doing the trick.

At some point I may switch that car to dual electric fans, mainly to just free up a little HP and less clutter in the engine bay. I tend to think if I set the on temps around 190 they fans would never get used unless I'm sitting still a long time, lol.

Dad is actually still running the stock shroud and clutch fan on his 69 GTO cooling a 700hp 571ci. He has a stock style 4 core copper radiator in the car that's been in there for 30 years. His car actually runs cooler idling than it does buzzing down the highway. The faster you cruise the warmer the engine runs. 65 mph on a hot summer day it runs 185-190-ish, which is nothing to worry about, but slow back down and the engine cools right back down to 170-175. I think eventually he will be doing a 1.5" tube Griffin and at that point decide if he'll go electric or stay with the trusty clutch fan.

[Bobalong]

My radiator is a 4 core. It's 25 yrs old, and I have a GM flex fan that supposedly came off of a station wagon or tow packaged car back in the day.
(previous owner got it from junk yard)

Any day above 80 deg at idle and I hit 195-200, at idle. Turn the A/C on at a traffic light and I'm at 210-220 in a heartbeat.
All the rubber inserts and shroud and factory parts are in place to tunnel air thru the radiator.

Any issues with mounting the fan around the AC condenser in front of the radiator ?

[HWYSTR455]

I would have to suggest to go over and check your system closely before adding any type of band aide approach fix. I suspect there's something else going on causing the hot running. If so, adding a pusher fan probably won't help.

I don't want to start a storm, but I don't think a flex fan is the way to go. It's hard to beat a clutch fan setup when it's all working properly.

25 year old radiator is a red flag to me, I would suspect it at least needs a good flush, and would suggest taking it to a radiator shop. The driveway flushes are pretty much just for changing the coolant at regular intervals.

Aluminum radiators are so inexpensive now, it's most of the time cheaper to replace than to have a radiator serviced.

Make sure you've done all the tips/fixes too, plated clearance, spring in lower hose, fresh thermostat, etc.

Once you've done all that, and you still have a problem, then start looking at possibly adding a pusher fan.

.

[Formulajones]

I'll also add that heat is also a reflect of the tune up. Everything has to be pretty well spot on with correct timing and fuel curves. If any of that isn't optimized the engines will tend to run warmer and contribute to an overheat issue. Compound that with a cooling system that isn't up to par and it makes matters worse.

I'm running some pretty old radiators in some of my stuff here without issues. 3 of them are their born with radiators and approaching 50 years old, lol. And the ones I have replaced I go straight for the Griffin 1.5" tube setup every time. The exact fit factory appearing tanks are about $600.

[70GS455]

Both.....single electric inside the shroud and mechanical with clutch.

Sent from my SM-T817V using Tapatalk

[jasonblair]

I have a BeCool aluminum radiator, and upgraded to the 11 bolt water pump on my 65, and even then it would get hot in traffic. Electric fans cool WAY better at low speeds, but I didn't like the sound of them, because they don't match the time period for the car.

So what I did was put an electric pusher fan on, which kicks on when I'm at low speeds, and keeps the temps in the normal range. But I also installed a manual override switch if I don't want the electric fan noise when I'm out trying to "impress" people.

Another benefit is that I can shut the car off and leave the electric fan running if I want to cool it down for another pass.

[David Brown]

I run clutch fans on my 1970 Bonneville 455, Chevy pickup 350 and Olds Cutlass 350 all with factory A/C, brass 4 core radiators and 180 thermostats. All will idle all day long in gear with A/C on at 180 to 190. A friend had a fully restored 71 454 Vette, griffin radiator and dual electric fans. He ALWAYS had a dead battery, meaning he needed to upgrade his alternator to handle the constant draw of the fans. I also live in south Florida.

[Will]

Flex fans don't get the job done.

You need the 7-blade factory heavy duty fixed blade fan and the heavy duty thermostatic clutch and a proper shroud. That setup moves huge amounts of air even at idle.

I would also get an old radiator checked out at a radiator shop. I rebuilt the engine in my truck a couple years ago and it started overheating on break-in. I wasn't sure what was wrong, I could see water flowing through the radiator when the thermostat opened and couldn't see any obvious corrosion/blockage in the radiator tubes but decided to pull the radiator and have it checked out as it was the 30 yo original. Sure enough, it was plugged up enough to lose a significant amount of flow. A new, stock replacement all copper radiator went in and everything's good now.

[engineer9]

Heat is transferred from the engine block by radiation and convection. The amount of heat transferred by radiation is primarily a function of the engine temperature T1^4 minus the surrrounding surface temperature T2^4. Given that the radiation temperture differential T1-T2) is relatively small, most of the heat will be transferred by convection. The amount of heat transferred by convection is primarily a function of the air velocity V^0.78. Therefore, you want a high-velocity wind blowing over the engine. You must compare fan air volumes and velocities, not fan type or number of blades. If the clutch fan and the electric fan are delivering the same volume and therefore are developing the same wind velocity, there will be no difference in heat transfer. Therefore: the more wind, the better!

[first gen Birdman]

I have got to throw out my two cents worth on this subject in hopes it help's someone out, I have been a Pontiac freak since I was about 12 and have owned and driven them my entire adult life , I currently own (3) 1968 Bird's (1) 1969 bird (1) 1967 GTO and (1) 1964 Bonneville Convertible all of which in the past have had overheat problem's ! I have owned one of the 1968 Firebird's which is a( 400,RA 4 speed coupe) since 1973 and it survived my teenage year's and 12 year's of quarter mile racing it , This particular car did not have a overheat issue when I bought it but as like alot of other Young know it all kids I had to make it faster and that meant screwing with it, so it did a multiple of engine upgrades including but not limited to bored the cylinder's 30 over and install a set of TRW forged piston's, the wildest Camshaft's(That I could possibly get to run at all at the stop lights), The biggest badass Carburetor I could get LOL and header's ect but soon I found that when ever I would drive the car and find myself stuck in traffic, which we all know cruising almost always is in heavy traffic (stop light to stop light) my Bird was running 210-220 Plus until I could get moving in traffic again, I replaced the Radiator with a new four core Radiator year's ago, tryed multiple fan blades combination's without success, overheating and stressing about the possibly blowing the head gaskets Just became part of owning the car from about 1975 to 2005. So fast forward . In 2005 I decided to pull the motor due to it had the dreaded Pontiac rear crank seal leak and the motor had been in there for quite a few year's and I just thought it was time to freshen it up before something came apart and destroyed a motor and a set of original RA 96 head's that I could not replace, I freshen up the motor, Valve job rings, bearings a BOP rear main seal set and a one piece oil pan gasket, ect , while the motor was out I sent the Radiator out to a local radiator shop and asked them to flow test it 3 day's later I got a call saying they were done and the radiator checked out fine ! reinstalled the engine with a new GM T-stat and performed the proper brake in procedure and then proceeded to drive the car and I found now that the car not only ran warm at idle (Which I calk up to the fact it was a new somewhat tight build ) but it ran hotter the high the RPM I ran , I returned to the shop rechecked all my adjustment's timing dwell and advance curves and ended up pulling the radiator back out and took it to another radiator shop which had me come down and inspect it with them to find the radiator was in fact two thirds blocked with silicone pieces from the past (maybe when the t-stat had been replaced)and calcium build up ect , I at that point replaced the radiator with what's referred to as a Dimple core 4 row Brass radiator But I believe the most important part was I came across a article on the Wallace Racing site on water pump mods ! I followed the Mods as suggested keeping my water pump impeller to divider plate clearance to .050 thousands of a inch. afterwards I reassembled the car still using the 7 blade Pontiac stock fan blade I have had on this car for year's. I now re road tested my Bird to find that at Idle and when running down the highway my temp is a consistently 180 degrees (and it is the Norm in my part of the country to have 100-106 degree temps for weeks in the summer which is when we all take out our toy's the most) and I can not ever recall it running this cool since I started making the mods when the car just a few year's old ! I can not express the pleasure of driving my car without always stressing and watching the temp,I also had a very similar issue with my 64 Bonneville it only uses a hot and cold lights to tell you the engine temp. Again when ever we would cruise in the car and got stuckin traffic very long idling it would turn on or flash the hot light and you certainly would not dare to turn on the air conditioning in this sweet cruiser if you had the top up on a hot day , I dealt with that for approximately 20 year's before solving the issue,like with the bird I also replaced the Radiator with a dimple core type, replaced the t-stat with a genuine Gm stat and removed the water pump and adjusted the divider plate clearance to .050 and amazingly the overheat issue with the Bonneville was also solved , I am now one HAPPY :Pontiac owner and not 100% sure which one of the three things I changed had the most effect but if I had to guess I would say its the water pump to divider plate clearance (which if it is more allows the water to bypass in the pump ! Hope this help's a few of you out as it has me ,I know I spent alot of years and frustration trying to solve my overheat issues before finding my success formula .

[Tom Vaught]

Great post with a lot of good advice on Radiators and especially reposting about the water-pump plate mod and how well it worked for your engines.

Tom V.

[JSPONT]

I had electric fan on my car, it worked great until it did not and left me stranded.
I have a turbo on the car, made a shroud and put a 7 blade flex fan on it. It worked but the noise and belt squeel got on my nerves. I put a 7 blade heavy duty clutch fan. It runs 170-180 not matter what, and I have timing locked at 25 degrees.
I made sure the water pump plate was as close as I could get it, and I put in an aluminum be cool radiator. The clutch fan kept my car the coolest, it never overheated, but it seems to do the best job for me.