Why is it, if it where that simple then that so many have found a cooler running engine after going to electric fans? I already had a new aluminum radiator with multiple new hoses, new clutch, seals in place stuffed around my shroud as well as foam pipe insulation stuffed in other places to force more air through the rad and tried multiple 180 thermostats but still the temps would creep up into the 190s and even hit 200 if I sat in traffic long enough with my 180 degree stat. all I changed to get the lower temps was a more aggressive roller cam the fans and stainless radiator hoses. In my mind it has to be either the stainless hoses or the fans that made the huge difference.
My spal fans draw about 30 amps as well when they are both running which is rare since unless the car is idling still for more than say 10 minutes the second fan never comes on. Time will tell if that changes when it gets hotter outside as I expect some change. oh yeah unlike before I have no shroud seal on my electric fans and even have strips about 2.5" wide on both ends on my rad that the shroud doesnt cover..

electric dual fan assy cost me $120 shipped... aluminum mounting brackets were about $35 but not needed. Alternator was $70 shipped an 8 ft piece of 6awg wire with connectors on the ends can be purchased for about $30 and a universal fan wiring kit is about $20 shipped (I added an unneeded but nice derale controller for $52 shipped which honestly would have allowed me to use a stock 60 amp alternator without an issue since my AC doesnt work and the extra 20 amps vs the 40amp non ac stock alternator wasnt being used..... . Of course my car was purchased used so at some point someone had already put an 80 amp replacement alternator in the car but I had replaced it with the $70 105a chrome unit due to charging issues I later found were due to improper wiring done by the PO causing parasitic draw. I dont know what my radiator cost me but I think it was somewhere around $150 shipped plus 2 new hoses and foam for the mounts foam for the shroud along with new mounting bracket because of course I found the old one was rotted when removing the rad and about $35 for a new heavy duty clutch. so im my case the new rad was actually more $$ than the electric fan install.

 

I put twin electric fans on my car about 15 years ago. I made every mistake. (just before I got on this forum). None the less, never went back. Yes I fixed up my wiring and charging systems errors. Just the room to work on the front of the engine, change a belt, etc was more than worth the effort. and yes. the car definitely cools better with the electric fans.
Mind you I drove it 15 years plus with the factory setup first.

 

It is simple. From reading the posts of the people who switch to electric fans, most also install a new aluminium rad at the same time and voila, the electric fans are given credit for solving the cooling problem. To me, that makes no sense. Air needs to flow through the rad. The method to do that is irrelevant so long as the minimum air requirement is satisfied to cool the coolant in transferring the heat to the ambient air. The two methods are electric or mechanical fans. So therefor, the rad was the problem in the first place. I replaced my rad to an aluminium rad and kept the clutch fan. Cools great! So I suggest to other folks based on the aforementioned to change out the rad only. Then replace the clutch fan only if there is insufficient air flow through the rad. If it still doesn't cool, then there is another issue but electric fans won't fix it. Sorry augie, but I think you had another issue i.e. the clutch fan was not not working as it should. At idle, my clutch fan blows copious amounts of air when fully engaged. More than enough to satisfy the minimum air flow through the rad to cool the coolant. All that said, the take away is the oem clutch fan works and electric fans are not required unless hp loss is a concern at 6000+ rpm operation.

 

So, I can see where some are mentioning timing as a cause of heat.
Which direction causes this heat, retarded or advanced??? I think I know but would rather hear from more experienced members.
Thanks

 

Generally, too little advance can cause overheating. This is the chosen method by GM to reduce emissions from their engines at idle: set the engine up to have even LESS timing and send ported/timed vacuum signal to the advance can (ZERO vacuum at idle). This would cause the cylinder heads to run hotter and burn off more hydrocarbons. What a plan....

Make sure that your advance can is working and make sure it is fed by MANIFOLD vacuum. If you have a stock [points] ignition system and essentially stock engine, set you ignition timing at 12 deg. BTDC at idle when the vacuum line to the advance can is removed and plugged. Reconnect the vacuum line and make any carb idle speed and mixture adjustments that might be needed. If it still gets hot, It's not the timing.

 

for the engine driven fan, you have an easy 20 to 30 HP at tap (idle) to drive a fully shrouded fan blade with 2 to 3 times the blade pitch with the radiator fully shrouded.

Electric fans will not come anywhere near that,

As resdoggie has mentioned most change multiple items when troubleshooting cooling issues so pin pointing exactly what fixed it is a guess

Neal

 

Again I replaced the clutch and the problem remained. what your claiming for the reason for the improvement is not what I experienced and that is why I had been so vocal in pointing out your theory doesnt match my reality.

 

A bad clutch? Wrong clutch? Something was wrong with your mechanical fan setup. It works great for just about everybody else because they pull more than enough air. So if we don't have a problem, why would you?

 

Its not the abundance of HP that matters while sitting in traffic at 750 rpm.. The fan on a mechanical system are turning at around 1000-1200 rpm when barely any power is needed to power the fan. Its not uncommon for some electric radiator fans to turn at 3500rpm though which can in fact help them push more air at the same idle situation (especially multiple fans).. And unlike a mechanical fans, drag against the engine robbing upwards of 30 hp in some cases, The electric fans put no such drag on the engine when off because while the car is at speed and the rad is being cooled by the same air the mechanical fan is fighting against while moving.

 

Weren't you the one trying to say everyone's experienced with temps on their cars are different and those experiences and temp reading data is only good for their car? Now you say the opposite is true? My car never overheated.. It just ran hotter than I wanted and that Sir is a VERY common complaint here so I wouldnt necessarily say they work great for everyone since not everyone has a stock engine or cooling system here nor do they all see the same climate.

 

Yes that was me but that was underhood temperatures, not engine operating temperatures. Cars running hotter but not overheating is a problem for some but not most. Most of us don't have a problem and the engine temperatures are normal using a clutch fan because it blows lots of air, period. Again, electric fans don't solve heating issues or cool the engine any better.

 

You might be interested to know that the underhood temperature experiments that @interpon and I conducted and posted both used our 79s with their stock cooling systems. That includes, of course, the foam insulation dams around the radiator, and the stock clutch fan. My 79 even has the stock radiator. It does have the Lars-style ignition tune, and a 180 degree thermostat, but if you can do better than a consistent 30 degrees below the thermostat temp in the engine compartment on a summer day, then I'd like to see the data.

I agree! It works just fine for my 79, which is why I hope the OP can solve his problems without resorting to an electric fan.

This, however, is just false.

I had a hard time finding CFM measurements for clutch-fans, but I did find a table of results from an SBC here:
http://carnut.com/ramblin/dyno.html

He was testing various fan blade configurations, too. At idle (800 rpm on the engine), the mechanical fans drew between 1100 and 1700 CFM. At 1600 RPM, the fans drew between 1400 and 2400. He also noted the massive HP loss, but you stated you don't care about that, so I won't elaborate.

The dual-Spal setup in my 80 is rated to 2780 CFM (and it is currently wired bang-bang, full on at 30 amps, or off, so I get all 2780 CFM when I need it). I'm sure that many electric fan installations are doomed to failure because they do not include a shroud, or use a weak fan, or don't have a circuit that can support the fan, or whatever. But with my setup, my fans do not come on AT ALL if I am driving around. They only come on at long stop lights.

Let us know if you can find different numbers. But at idle, and off-idle, at least some electric fan win for CFM. Going down the road, you don't need fans at all.

 

This data coincides with my experience with my dual spal clones... and explains why one fan almost does the job by itself.

 

Tell us what the minimum number of cfm is required at idle to keep an engine at 180* with a 180* thermostat. And then tell us if a 7-blade mechanical clutch fan in proper working order can meet that requirement, or not. But I know you can't provide that information, nor can I. But what controls the engine temperature? The thermostat! The rad is just a reservoir of coolant which can only enter the engine if the ts reaches its opening temperature to begin opening which is below its rated temperature. So getting back to the rad, the coolant is cooled by air passing through the rad. The rad doesn't care how that is done but it does need enough cfm to cool the coolant based on varying engine load and engine temperature and controlled by the thermostat opening. So if a clutch fan can cool this reservoir of coolant and let there be no doubt it absolutely can because GM engineers who do this stuff for a living designed it that way and many of us in here can attest to that. Read the threads on cooling. Lots of us keep our modified engines cool without issue or we are all liars. So, are we? And yes, I don't care about HP loss because my car still puts down 357 at the wheels and that's good enough for me.

Edit: In a nutshell, it doesn't matter if, if electric fans can cool the coolant in the rad below a temperature than a clutch fan can achieve because it would still make no difference in keeping the engine at 180*, which is what we are discussing. It would just take less coolant to enter the engine block to keep it at 180*.

 

The stock clutch fan set up worked so well that GM installed an auxiliary ELECTRIC cooling fan in the later models with A/C.

 

Here's what a lot of people miss when installing electric fans. The fan shroud has to be sealed all the way around the outer edge. if you do not do this, then you will lose a lot of your fan pulling capability! The fan(s) will pull the 'easy' air through the unsealed sides, before they'll pull through the (harder) effort radiator. My buddy who set up drag boats showed me this with a thin strip of paper on my C3. With the fan running, he held a strip of paper alongside the outer edge of the shroud and sure enough, the end of the strip pulled towards the edge. That is air that is not being pulled through the radiator! I used high temperature rubber foam strips around the full 360 degrees on my stock GM dual electric fan to accomplish this. BTW, the GM dual electric fan that they used for decades in the Corvettes, is the exact same fan as the Camaro, the Cadillac and the GMC trucks. There's no difference. I got mine five years ago out of a '89 Camaro for $40 and it still runs perfect.

 

Exactly, the electric will not do the job on its own but was a compromise to help with AC on a car that already has a marginal cooling system due to space.

Neal

 

While the fan may be turning at 1000 rpm they also have 3 times the blade pitch and larger blades which adds up to less slip and way more air flow.

If I remember correctly the CFM ratings on the stock fans were in the 5000 cfm range,

Neal

 

I think we may have gotten a little off topic from what the OP asked,

I suggest start here, flush your radiator, check condition of the interior of the radiator it may need cleaning, make sure the core support seals and all there and still in place, verify the fan clutch is working as intended

Neal

 

I see two completely different CFM claims on mechanical fans above... The article linked above shows a trend that just doesnt coincide with 5000CFM unless that mayby WOT...
heres a quote from another thread since the ops last response was that hes going to look at electric fan setups.. I do agree first the rad should be flushed and seals checked. In fact I think I may even install some seals on my new electric setup even though it working so well without them. havent hot peak summer temps yet.

Btw its not only the thermostat that controls engine temps... If the cooling system cant keep up consistently at different rpms... thats been the whole point of this conversation. If the car runs at proper temp while moving but overheats while sitting the issue is either waterpump or airflow at idle plain and simple and idle is when the stock fan turn its slowest while the clutch is engaged... Hence the 81 aux fan to boost performance while the AC is running... Seems this worked so well they ditched the mechanical fan in vettes altogether from that point on if the mechanical fans really moved anywhere near 5000cfm when they are actually needed at idle the aux fan would simply never have been installed... Think about it, especially when comparing it to a c5s 1700cfm fans.. Theres just more to it.