Flex-a-lite cooling fan, Do the work well

[stringpickin]

Hello and good day. I have installed a flex-a-lite dual electric fan on my 70 chevy pickup on my brand new 383 engine with Edelbrock EFI.. My engine has about 60 miles on it. It has gotten towards a hundred degrees out for the first time this year and today, as I was doing the final break in runs, my engine peaked at 221 degrees.. SCARED me to death.. I had to turn my truck around and go back down the highway hill, and it did kool immediately down. Turned back around go up, and it did the same thing again, I pushed it a bit further up the hill and repeated the down the hill procedure again, and turned it around and finally got up the hill to my town. After hitting flat land it went down to 203 and to 198 fairly quickly. The Question.. Do these fans offer enough cooling power?? they are rated at 4500 cfm a minute. As far as I can tell the standard flex fan rated at around 3500.. Do you think I have another problem going on, or is it just a fact that these electric fans really aren't enough to handle 100 degree heat, a 383 with a 700r4 tranny in a 4x4? Not to mention if I start towing something. Please,, Any experience would be greatly appreciated.. I have the same heavy duty 4 core radiator I had with my previous 383. Been rotted out and cleaned. New high flow water pump. No air bubbles in the system as far as I can tell. could it be because of the New engine running hot?? It just seems like I never had heating problems the last time I did this.. Would a few degrees advanced more then needed cause the problem??? thank you very much for your replys, suggestions and or help.. Barry

[shuttermutt]

Well, a combination of 100-degree heat and towing uphill will all certainly lend themselves to high temperatures. Have you got a fan shroud on there? They really do help more than you'd think.

[stringpickin]

Hello Mutt.. The flex-a-lite fan system has its own built around the fans shroud..There is about a 1/2 gap across the length of the bottom that could be closed off. I would be amazed if blocking that up would make all the difference. Now to clarify, I was not towing anything today. But towing will be happening after I get about 800 miles on it. The advance timing statement is not a fact, but rather a pondering. I need to check it in the morn. The Edelbrock EFI system and computer chips is above and beyond my common knowledge because it is brand new. Before I just had the HEI. I would set the advance until no pinging and forget it. The EFI comes with module to actually set program settings. All new to me. I wish I knew how to set it all up and tweak it right. But I must learn it. I hate to be learning that on a new engine. But the price we pay when we play.. Thanks Mutt.. And your right, shrouds make a big difference.

[shuttermutt]

Once again, I've got to smack myself upside the head. When I read "Flex-a-Lite" I missed the "dual electric" part. I just figured you'd swapped out the fan. Damn, I need to go to bed, have a beer, or both!

Hmmm...

Advanced timing generally won't cause overheating unless it's masking another symptom. Probably a more likely candidate is that you're running a bit lean? A new engine with a lean condition can make for higher than normal running temperatures. Too much antifreeze:water? Underdriving the water pump? Thermostat problems?

[gr8scott51]

Did you do a proper wear in on your cam bearings? That first break in period is always kinda hot.

[Shane65]

You've got quite a few changes that any one or combination can be the problem. First verify that the engine is not running lean. I'm not familiar with the Edelbrock efi. Can a laptop be connected to the computer to see what the fuel mixture is or does Edelbrock have a means for this. The electric fans shouldn't even be running on the highway. There should be enough air flowing through the rad to cool the engine. Could even be that the fan shroud is impeding air flow. Some electric fan shrouds have windows cut into them that are covered with a door(rubber) that can let some of the highway speed air get out. This increases the amount of air that can get through. New engines do run hot for the first while but should get cooler as they get broken in. Cast exhaust manifolds? Watch out for getting them really hot then going down a hill to cool the engine. What happens when you go down the hill is that you are hardly touching the gas pedal but cool air is going through the engine and when super hot manifolds see cool air they can crack. This happens to motorhomes often enough. Rad should be good. I'm not convinced that high flow water pumps are neccessary and have been know not to make things better. Don't engines run hotter with the timing retarded as opposed to advanced? Have you got a high volume thermostat(Robertshaw are good ones)?

[Stocker]

You mentioned 221 degrees - assuming that's an accurate reading, while it's at the upper range of acceptable, I wouldn't be too alarmed. I can't give you exact numbers, but while water boils at 212*, the boiling point is increased when in a pressurized system, and also increases when antifreeze is included in the mix.

[walker]

Try backing off the timing a bit, and if you can richen your mixture up a wee bit. You may even get a colortune kit to see if you are runing too lean. Also, cooling fans do not do anything when you are driving at speed, the forced air coming through the grill is what does your cooling. Fans keep you cool at idle and low speed driving. I had the same trouble when it got over 100* here too. The timing did the trick. Prior to that I had replaced the t-stat with a 160* unit, drilled 3 3/16" holes in the t-stat as a bypass, etc. You may even try putting in a new sending unit.

[stringpickin]

Thank you everyone very much for your input. I feel well armed for the morning. After I get the timing checked and right and make sure the mix is right I am thinking of installing a clutch fan anyway. Just cutoff the original cowl to the size of the flex-a-lite cowling and attach it to it. Seems like that would be the ultimate cooling system. Anythoughts to why not do that?? It should stay cool accross the sahara and not cost a lot of fuel. The system would run so easy that the clutch fan would rarely engage fully. It seems that the ram air is reduced with the flex-a-lite, even though it has the sections with flaps for ram air flow. With the clutch fan slightly engaged it may make up for the loss of ram air without costing to much fuel.. thanks again,, what do you think?

[stringpickin]

Hello and Good Day again Guys. Well the saga continues.. Today I did not fix the problem,, however have eliminated the timing issue, the mixture issue..Radiator is brand new modine, so unless have a blockage in the brand new engine, then it comes down to the Elec. fans cause negative results on hot days and working the motor. Apparently the surmisal is this.. The electric fan unit does not allow the ram air to come through effectivly. and,, this means that as the fans are turning because the thermostat says I am hot, turn on,, it must cause some kind of an adverse pressure problem and cause the air to stall in front of the radiator.. I talked to a guy today that ended up throwing on his clutch fan after he experienced the same problem as I. It fixed it. He plans on going back to clutch fan only.. Heard of another guy I know, that messed with electric fans on his newer chevy.. took them off after 3 years of suffering with heating problems.. must be they block and cause air flow problems at highway speeds.. would type more, but dinner is ready. what do you think?

thanks again..

[Shane65]

The fuel loss issue converting to a clutch or flex fan is very small. You see ads for the electric fans claiming XX amount of horspower savings. In reality those claims are based on the real high end of the rpms of an engine. At normal street speeds the engine rarely goes over 3300(this will depend on your gear ratio)rpm in typical driving. The extra horsepower needed for the fan isn't that great. Inflating your tires a little more would likely gain back the loss. I really like the mechanical flex fan from the 70's Cadillac 500 c.i. engines. Lots of air at slow speeds and quick to change pitch with the rpms rising.

[kwmech]

Been thru the deal with electrics my self and in my opinion they suck, I can guarantee you that within a year or 2 they fan WILL come apart at the motor and throw the blades wherever. Another thing is the quality of the fan temp sensor, always had problems with the sensor getting the fan to come on at the right temp if at all. I even at one point put a separate toggle to bypass when the sensor decided not to work. The best thing you can do is put back on a factory 19'' 7 blade with a heavy duty fan clutch. The so called horse power savings is not enough to worry about.

[walker]

I agree about the fan with the fan clutch. Also, one more thing that I was thinking about is that my truck was originally from AZ. It came with a heavy duty radiator and some strange bypass in the water neck and as I recall had the temp sensor up there too. If you have no bypass from the water pump to the intake man/t-stat housing, and have a shut off valve in the heater core, or have no heater hoses on, then you have eliminated your bypass. I don't know to what degree it affects these trucks, no doubt in most areas not at all, but here in the desert it may be different. I do recall some modern cars requireing a bypass not to overheat. In fact I have a buddy with a chrysler of some sort, blew a heater hose, blocked it off, then overheated. He then made a loop with the hose from water pump toi the intake and it ran fine untill he bought new hoses and made the repair. Long story short, make sure you have a t-stat bypass.

[mrein3]

I'll take a swing at this one.
In your first post you state your truck is a 1970. 1970 has the grill with the aluminum bar running horizontal across the radiator. Somebody in Nevada claims he chased mysterious overheat problems for years until one old timer said it is the grill. A switch to a 71/72 grill fixed the problem.
I have the 69/70 grill on my truck. I took off the 71/72 style. I like the 69/70 look better and up here in Minnesota it just doesn't get that hot.
stringpickin - you don't mention your location (you should update that) but we probably won't see 100 degrees this year so I'm guessing you are at least south of MN. Don't go hacking the bar out of the middle of your grill but if you know somebody close with the 71/72 grill you may want to try that.

I was having overheat problems with two of my drivers this spring. An old timer said if it overheats standing still it is the thermostat. If it overheats on the road it is the radiator. He was right on both of my vehicles. Being that you overheat going down the road you can probably rule out the thermostat however I'd change that before I bought a new radiator. If you aren't getting air flow across your radiator (from say a grill in the way) you would have symptoms similar to a bad radiator.

[crazy longhorn]

I am sure things are different in some parts of the country, due to climate. I run a pair of 14" flex a lites , on a homemade shroud (they are said to pull 3300 cfm). here in Illinois, we see 95 degree days, & that doesnt seem to cause a problem with overheating. Even on the hot days, the fans dont need to run much when the truck is moving. even in town, if i stay back to 5th gear to keep the revs up a bit, the fans dont run much & I stay between 180 -190 on temp. i still have the 69 grill bar, but no inner grill & no inner fenders.....maybe that is helping the situation? From the sound of the size of your fans.....I would think they should do the job. Does the truck have AC? Sometimes a dirty or bug plugged AC condensor can cause overheat problems. Best of luck,crazyL

[SCOTI]

Originally Posted by kwmech

Been thru the deal with electrics my self and in my opinion they suck, I can guarantee you that within a year or 2 they fan WILL come apart at the motor and throw the blades wherever. Another thing is the quality of the fan temp sensor, always had problems with the sensor getting the fan to come on at the right temp if at all. I even at one point put a separate toggle to bypass when the sensor decided not to work. The best thing you can do is put back on a factory 19'' 7 blade with a heavy duty fan clutch. The so called horse power savings is not enough to worry about.

I would think the factory would still use clutch type fans if electrics were crap. The key to this could quite possibly be the brand. I know others have had good results w/flex-a-lites, but possibly they cant pull the cfm you need.

I would try an OEM electric fan for a truck w/a turbo diesel (any brand that will fit your rad dimensions) or even something off an LS1 f-body. I know of a guy from the internet that used a single OEM electric fan to cool his 69 camaro w/an all aluminum 540ci supercharged big block. He was using the 'BeCool' twin set-up w/matching shrouds but still had temps climb to 205°F on hot days. You can imagine his concerns on a motor like that. After switching to a Ford/Lincoln style electric fan (and w/no other changes), he said his temps never exceeded 185°F in the worst conditions (a/c on in stop & go traffic).

[stringpickin]

Hello again.. Well, here where I live it pushes a hundred degrees and over during the summer fairly often. The other day it was 97 degrees and coming up a 7% grade when the overheat problems occurred. On flat land I could run the air with no over heat problems. On the new trucks are they using only electric fan units now? I like the 70 grill better than the 72 grill also.. As far as the bar accross the front causing problems, it has never been a problem before. Maybe that tied with the electric fan arrangement causes a problem, but hard to tell.. It is apprent that the ram air is enough to work on flat land and in low work condtions with the flex-a-lite installed. But it seems to be so far that when the engine has to work hard, the air flow situation is not good enough to keep it kool. It seems as though we have it down to one thing. I am in the middle of pulling off the flex-a-lite and putting on the old shroud and fan. If it works, well we know for sure what the problem is. If that is the case, I go back to stock. Ashame, but whatever works best is the deal.. Will keep you all posted. And thanks man for all the input.. Great to have such a great forum to help each other out.

[stelth2002]

It was mentioned before, but i think you may be running lean enough to cause this. Does it have extremely good power with no dead spots in the entire rpm range?

[stringpickin]

Hey there Stealth,, Yes a few posts ago I had stated that the fuel mix was ruled out.. but I did not state that it excelerates very nicely.. The indicator light on the EFI module hovers pretty nicely between red and green, leaning towards the green now. We riched it up a bit. The pipes are brand new and so far looks like it is running very nice. Just waiting for the guys to call me now. The stock shroud and fan will be back on it pretty soon, then I will go find out for sure if the fans suck(no pun intended, but funny) or not.. thank you very much for your input..

[SCOTI]

Originally Posted by stringpickin

The stock shroud and fan will be back on it pretty soon, then I will go find out for sure if the fans suck(no pun intended, but funny) or not....

Actually that's a good way to test how much airflow the current fans are pulling. Take one well worn t-shirt & hold it in front of the grill w/the engine running. Does it want to suck the t-shirt through the radiator? It should. If it doesn't, possibly the fans could be arranged differently (ex: instead of side-by-side, stagger them diagonally from top/right to bottom left).

[stringpickin]

Hello and Good day everyone,, Well,,, I am now running with the original shroud and the after market flexfan I have been running for quite a few years. It looks as though my heating problems are gone but still a slight question.

I contacted flex-a-lite again to tell them what I was going through. They did not say that they know they have a problem in the application I had. However, he did say that in the big block motors they are not enough to keep them kool. I discussed this problem with him and I suggested to him that it may be possible that the proximity of the fans to the back of the radiator while they are running at full bore because the sending unit turns them on is actually stalling the ram air. He said, you know, you may have something woth looking at, because our engineers have not been able to fix the problem with big blocks or find the reason.
He stated that it doesn't make any sense to them because even on some of the newer big block trucks wiht wider radiators where the 5500cfm models can be used should absolutely work because they matter of fact pull about 1000cfm more than the typical stock fan setup in there opinion. So the way he sounded he was going to discuss it with the engineer. My thought that I shared with him was if they would move the fans further back in to their own shroud thereby keeping them another inch or so away from the radiator, the ram air may be allowed to come through and nudge the pressure zone back far enough where the two systems(ram air and the electric fans) gather together and start a conducive window flow pattern.. So, here I am with that noisy as all get out flex fan.. I hate it.. I think I will break my motor in with it cause I know it keeps it kool and in a while I will go to a factory heavy duty clutch fan and forget it. Also, I ran into a very good mechanic today that had put a twin electric fan system on his 425 horse camaro.. worked great until hot summer came along and started pulling hills. And AC was out of the question as it has been with the set up I had but now is ripped out.. lol.. He messed with it for one summer, the next summer came around and he started noticing it heating up again, and ripped them out and went back to stock clutch fan.. So, it seems.. engines that produce more horsepower need something other than these electric fan set ups.. You know what the real drag is though.. always something,, the last two days that I have been testing it up the same hill, it has been about 10 degrees cooler out.. yea,,,,,, so,, what do you think, when it heats up is the flex fain going to keep up?? always something....

[sam's 72]

If I am not mistaken. You can set these fans up to push or pull. If this is the case, make sure they are set up correctly. They need to be set up to pull the air from front of radaitor to back. I have the same exact fans on my truck, I have not started up the truck yet. It is also a 383 pushing about 450 HP. If you have every thing set up right. And this is still happening, you got me worried! I have a new four core radaitor, high flow alum. water pump, 180 temp. termostate. Alum. heads. I hope these fans work. One more thing to look at, is your tempeture sending unit. If it is near the exhaust, screwed into the head. It is possible that it is reading some of the temperture comming off of the exhaust manafold or header. Mine is mounted right by the header. I am going to use some heat wrap on it to try and keep it from getting some of the reading from the header itself.
Sam

[stringpickin]

Hello Sam.. yes,, these are set up to pull and they are going the correct direction. Someone mentioned the grill in the 72 may help the ram air effect. I wonder if you won't have any problems. It is hard for me to imagine the bar on the 70 grill would actually make the difference, but I guess it could. I have the modine 4 core, high volume water pump, 180 thermo, cast heads. I wish the fans would have worked too. I am still hating the noise of the flex fan. Not bad when I get in to over drive, but I have another 6 hundred miles or so to go before I use overdrive much.. I don't want to lug my motor at all.. For all intents and purposes,, my heating problem is gone. With the electric fans on I saw 223 and bounced for a split second to 231. Since replacing the electric fans I have seen 203 as max, climbing a hill at about 95 degrees out with AC running.. I get the urge to try the fans again, cause I keep thinking maybe the engine was just breaking in, maybe the rings were generating so much heat, maybe I had an air bubble.. maybe this maybe that.. But I can't afford the time right now. I have a long trip coming up in a few days accross the arizona desert that I have been getting prepped for.. And I want as much cooling ability as I can possibly have right now, so I am going to stick with the flex fan for the time being.. I can only say this, it seems that the moment I took of the electric fans my heating problems abated.. You may want to consider putting a stock fan and shroud on for break in unless you don't have any hills to climb in high heat. I hated to see my new motor bounce to 231,, even though it was for a mili-second.. As far the heat sending unit, I believe it is plenty far enough from anything to cause a problem. You must have some 12.5:1 ratio and some whild cam and valves huh?? That baby ought to run.. I am very very happy with the torque and power of my new motor. Some say mine may be 380 horse.. I said 360 to be moderate.. But in either case about 80 horse more than my last 383,, and all I can say is I love it.. Runs like a bear.. Best of luck..