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I have an 80, with a 350 crate motor, 20,000 miles on it. It was originally a Florida car, Long Island now, and has electric fans which constantly stay on. It also has a clutch fan. The engine is stock except for an edelbrock performer manifold, carb, and it has headers. The problem is when I run the AC the temp will rise up to 220+. I have replaced the water pump with a high flow, thermostat is a 160, and the radiator is less then a year old (stock). Without the AC on the car runs at 160 to 165, maybe up to 180 on a hot day in traffic. Turn on the AC and up the temp goes, car will also get sluggish. Question is will it be worth replacing the clutch fan with a flex fan. Would it make much difference? Any ideas are appreciated. Thanks, Tony53
Post pics of fans…
odd you have both electric and clutch.. maybe you have too much restrictions in way and condenser heats up.
and i would go clutch not flex
Get the electric fans to work properly instead, or replace them with ones that do work.
Here's why you should never run a flex fan. And if you have properly rated electric fans (and an alternator to handle them), you can likely eliminate the clutch fan.
Agreed, Flex fans are bad in every way possible. Rob you of horse power. And can blow apart destroying whatever they hit. And really don't help cooling over a properly working clutch fan or properly working electric fans.
Clearly with all these fans the previous owner was trying to fix a problem with it overheating.
Something isn't right. I would look at other solutions than just the fans.
start with the rad and condenser. PITA to pull the radiator, but uou can take the top brackets off and tip it back enough to get a hose in there and rinse the front of rad and back of condenser. pull the electric fan or fans and clean the junk out behind it too. and the front of the condenser. do you still have the fan shroud? or was it ditched to make room for the electric fans. do the fans blow the right way? ya never know how clueless a prev owner was. and truthfully we have to assume you are challenged in that department too. so, if we ask questions that sound a little demeaning, we gotta make sure the simple, cheap stuff is covered before we have you pulling heads and such. do you knpw how to post pics? look at the icons above where you are typing. square block with mountains and moon. click it. easier with laptop than phone, but u gotta email the pics from phone to laptop... one more question. does temp climb at 65 on the LIE or southern state? or just on roads with traffic lights?
From: Some days your the dog and some days your the hydrant.
Royal Canadian Navy
Your one year old stock rad can't handle the extra cooling required when running the a/c, imo. Was the replacement rad for an a/c equipped car? You don't need a 160*. A 180* is more ideal.
There are more threads on here over the years on overheating than carter has little pills. Do some reading.
Also. Crate motor, is NOT stock motor. Stock Rad is simply not up to the task. Hi-flow water pump without high end High flow thermostat is not getting you anywhere! High flow 180 degree thermostat, 4 row aluminium radiator. Fans that blow enough. Cheap eBay fans don't cut it. (Ask me how I know!). Proper switching and wiring for fans. Proper fan shroud is absolutely imperative. All the seals around the radiator. Lower radiator hose with spring so it doesn't collapse.
The list goes on.
I have an 80, with a 350 crate motor, 20,000 miles on it. It was originally a Florida car, Long Island now, and has electric fans which constantly stay on. It also has a clutch fan. The engine is stock except for an edelbrock performer manifold, carb, and it has headers. The problem is when I run the AC the temp will rise up to 220+. I have replaced the water pump with a high flow, thermostat is a 160, and the radiator is less then a year old (stock). Without the AC on the car runs at 160 to 165, maybe up to 180 on a hot day in traffic. Turn on the AC and up the temp goes, car will also get sluggish. Question is will it be worth replacing the clutch fan with a flex fan. Would it make much difference? Any ideas are appreciated. Thanks, Tony53
When my stock 79 L82 with AC, factory electric fan, and factory fan clutch would freeze me driving even when it was 114 in las vegas. typically over 3 months of over 100 degrees every day. It worked for many years even when I hot rodded the motor. L-82 came with a big 4 core radiator and the factory electric fan was thermostatically turned on and off.
Your radiator is sub standard or your electric is not enough CFM
another possibility. gets sluggish when AC on. a blockage in the orifice could make ac pressure run high, put a big load on the compresser and fill condenser with very hot "freon". which could overwhelm the rad. does ac blow cold well? can you lay your hands on a set of ac gauges? even the fill hose with a low side gauge will give you some possible answers.
Don't forget to check all the seals around the radiator and shroud. Fans will do nothing if the air is not being pulled through the radiator.
I don't have AC but my 496 big block has no issues in 95+ FL heat. Good seals, factory AC spoiler extension, DeWitts radiator and Lincoln MK VIII fan. 180 stat , 195 on for fan, 185 off.
Get a infrared thermometer. They're really inexpensive anymore. Verify the temp when it gets warm, then see how much the radiator is actually cooling. When I wrenched, a 30 drop across the radiator was the rule of thumb we used. Using a infra red or thermal camera, look all over the radiator for hot spots, this will show the plugged areas that aren't flowing coolant.
The radiator may have plugged up already even though it's "new". We had a customer whos radiator we replaced and a year later it was over heating again. When we removed it, we found it full of rust. You can't assume ANYTHING. I just replaced the flexfan the PO installed. It's a dangerous and power wasting turd.
Last edited by centralcalvette; Jun 15, 2022 at 02:57 PM.
Reason: UPDATE
Get a infrared thermometer. They're really inexpensive anymore. Verify the temp when it gets warm, then see how much the radiator is actually cooling. When I wrenched, a 30 drop across the radiator was the rule of thumb we used. Using a infra red or thermal camera, look all over the radiator for hot spots, this will show the plugged areas that aren't flowing coolant.
The radiator may have plugged up already even though it's "new". We had a customer whos radiator we replaced and a year later it was over heating again. When we removed it, we found it full of rust. You can't assume ANYTHING. I just replaced the flexfan the PO installed. It's a dangerous and power wasting turd.
"Thanks" to all for your replies and advice, it is appreciated. I will start with checking the radiatior and condensor, then look into the electric fans. I will also get some pics posted.
There are more threads on here over the years on overheating than carter has little pills. Do some reading.
Also. Crate motor, is NOT stock motor. Stock Rad is simply not up to the task. Hi-flow water pump without high end High flow thermostat is not getting you anywhere! High flow 180 degree thermostat, 4 row aluminium radiator. Fans that blow enough. Cheap eBay fans don't cut it. (Ask me how I know!). Proper switching and wiring for fans. Proper fan shroud is absolutely imperative. All the seals around the radiator. Lower radiator hose with spring so it doesn't collapse.
The list goes on.
A lot of us are running the debranded spal "clones" or be cool branded fans with the logos ground off and sold as generic. these are about $120 on ebay and work exactly the same as the dual 11" spals. there are so pretty useless garbage fans on ebay though that just dont move much air.
A good thermostatically controlled clutch fan with the coil on the front of it will do well. I've been running stainless steel fixed flex fans for 40 years and never had an issue. I spin this thing 8000 RPM through the traps with it. The first one was on my 427 Camaro and it kept it cool. Same fan went on my Vette for many years....I only bought a new one because the other one was dull and i didn't feel like polishing on it! I've tested it on the chassis dyno as well as at the track and the HP loss is NOTHING like some videos and on-line hypesters will regurgitate. I actually tested it back to back at the track with it on, with it run by an electric motor and completely off. Never did see a difference on ET or trap speed while running 9's@140+ MPH.
And it keeps it cool. No A/C...but it's a stock 4 core radiator with a stock shroud, stock pulleys and 555" of big block with twin turbos.
I love it when actual facts and experience triumph over hype and BS.
Thus the reason for multiple people comparing different fans on a dyno for real COMPARISON data and those people sharing that data. Lots of BS biased opinions based on limited experience and myths out there. Theres videos of different shops with dynos doing this comparision too and the results vary but always show the same overall trends sure theres variables with will make the numbers closer or wider between the two. Fixed fans were phased out of production vehicled decades ago just as clutch fans have been following for real tangible reasons though and we already know it wasnt for reliability or cost savings.
I have personal experience with 2 c3s and the cooling systems in both being changed. one going from stock cluthfan to replacement clutch and then electric fans all the while having the same radiator installed and the other going from a stock rad with twin garbage cheapy fans to a fixed flex fan to the stock clutch fan setup. as far as cooling abilities the twin spal type electric was superior to the rest. As far as power, I would be just making an unfounded observation with no proof to back anything up if noticed so im not even going to make claims. the lowest hp gains ive seen in a comparision video was a stock chevy pickup that only picked up 7hp on the dyno from the swap from a clutch fan. To me the gains to be had are low hanging fruit though compared to the money people often spend here for less HP results.. I guess if the electric fans were more blingy and polished they would be more popular and make more hp in the eyes of more folks.
Its not a hypothetical thing that no fan hanging off the engine (or electric fan turned off because its not needed and provided no drag on engine) wastes less energy and in turn frees up at least a few more hp. The engineers know this too and its a key reason mechanical fans are typically only found on older vehicles these days. People are resistant to change. I can pull up old forum threads where hot rodders argued iron heads were superior and made more power than aluminum and other threads arguing carbs are superior to fuel injection but its finally been generally accepted that the latter has more potential when set up right. Of coarse like with anything, improperly installed or garbage designed components will give anything a bad reputation. This has been the argument also for flat tappet vs roller cams.
Last edited by augiedoggy; Jun 16, 2022 at 08:23 AM.
The other distinction I like to ponder is identifying what are the gains you get out of a good dual electric fan setup, or like the new Dewitts single brushless fan. Here is what I know for sure, and what I a considering on the 69 project, which will have a VortecPro 468 iron head big block with factory exhaust manifold, Quadrajet, etc.
1. With a Dewitts aluminum radiator, with either their dual Spal fans, or single brushless fan......I will easily have room for a spreader bar.....which I find very desirable, as it made a noticeable change on my 77. This is the overwhelming reason I would consider electric fans.
2. As for cooling the engine.....I know this setup will work well....no argument there.
3. What does this setup do in terms of evacuating engine compartment heat....which ultimately becomes heat inside the car?? Does the electric fans setup evacuate engine compartment heat better or worse than a clutch fan with a shroud????
4. Do I want to deal with electrical wiring modifications required / high capacity alternator just to have electric fans. NO, not really.
5.. Lastly....when I open the hood on a 69 Corvette....do I want to see modern electric fans......my answer to that is NO.......but I could be convinced if all other things are beneficial.
FYI......I don't, and won't, consider HP loss a factor in this decision....Its such a small number, no matter what it is, its truly irrelevant on the street.
Oh....and I prefer carbs.....FI only adds modifications and complexity for which I prefer to avoid. My Holley Street HP, NO choke, double pumper works just fine on my 406.
Last edited by Shovels and Vettes; Jun 16, 2022 at 05:22 PM.
Good electric fans ARE a good thing for the reasons cited. My '32 Ford 5 window has a full time electric fan arrangement. I bought it that way and plan to change it to thermostatically controlled eventually...but it keeps temps dead on the money at 175-180* regardless of weather or conditions even with AC running.
Certainly new cars are all about power management and fuel economy...so removing any drag is a good thing. They are also all about temp management for emissions...so the need to warm up an engine quickly is paramount. I'm amazed at how fast my newer pickup comes up to temp and the heater is warm...I mean like a minute or two before I get out of the driveway!
And the less HP you have...the more likely you'll "feel or see" an improvement in performance as far as power goes. My 871 HP engine running 9's at the time won't notice a few HP one way or the other. 250 HP packages will notice it easier. When I tested the fans on a chassis dyno it was making 615 RWHP at the time (fresh off the engine dyno making 732 crank HP). When I removed the fan completely and made multiple runs I saw 2-3 RWHP at the worst...which IS a change....but easily within run-to-run variation.
At the time of these tests, I had already purchased the fans and a larger alternator to provide enough juice to run them. When I looked at the dyno results as well as the weight of the fans and alternator....it just made sense to stay simpler and returned the parts.
It currently makes 1240 RWHP and runs 8's@162 MPH with the flex fan in place as well as PS operating. Again...the more HP you have...the harder it is to quantify smaller changes. I even made my 200 MPH runs at the TX mile with the flex fan running as usual.
As far as them coming apart....I can only report what I've seen. Frankly over they years I've never seen one come apart. I've seen stock ones crack a blade and come off.....but not even sure i ever actually saw one of the old green fiberglass ones scatter. I'd be likely to believe it...but I bet something cracked it first.
As they show in those tests....various fan designs create different losses. I work in the large truck world and they have some electric fans these days that are huge....and eventually we'll see 48v-72v systems to help it all work.
Clutch Fan or Flex
