My 454 constantly overheats while at an idle. As long as the car's moving along, it sits happily at around 165-170 degrees. But once it's stopped for more than about a minute the temp starts to rise. it doesn't stop rising until I get her moving again. I just bought a new electric fan (16") and I'm planning on installing it tomorrow afternoon. I'd really like to pull the flex fan off the waterpump and run the electric one as a puller (I like the way it cleans up the engine compartment without it). My question is this: Will this electric fan keep my engine cool enough at an idle all on it's own or should I just plan on running it as a pusher and leaving the stock fan? Thanx in advance guys!

---Chris

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454cid '69 SS

A few things to think about:
Are you running a stock alternator? If you are you will have some trouble running any accessories and the fan at the same time because the fan pulls a lot of juice. And the fan size and CFM may not be enough for that huge engine. Most new cars with electric fans have alternators in the 100 amp plus range. Are you running a fan shroud? The fan shroud helps direct the flow of air through the radiator around the fan. The flex fan is not always a good choice. The car probably originally came equipped with a seven blade steel fan and themostatic clutch pulls amazing amounts of air when the clutch is engaged. I would also check the condition of the cooling system. Is the radiator clogged or are the fins blocked? Is the coolant clean and is the mixture correct? Is the thermostat working properly?

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65 Danube Blue 4 door wagon, 350/330hp crate with 700R4, Factory air, Factory am/fm stereo.

[This message has been edited by JimN (edited 02-09-2002).]

The radiator is a brand new (about 2,000 miles on it), 4-core Griffin radiator (15psi cap). I just changed the coolant about 500 miles ago when I replaced the lifters, pushrods, and rockers. I ran a 50/50 mix plus one bottle of RedLine WaterWetter. The themostat is also a brand new 160*. I am running a fan shroud but I'm also the first to admitt that it's probably not doing it's job properly because it doesn't sit flush all the way around the radiator (kind of gaps near the bottom). As for my aternator, I've rebuilt it to a rating of 160 amps (not stock unit). I don't have an A/C and I don't even have a stereo so that should be more than enough. http://www.chevelles.com/forum/smile.gif Oh yeah, the CFM rating on this fan is 1625. Not sure if that will help at all or not. Thanx for the reply Jim!

---Chris

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454cid '69 SS

Overheats at idle? Is the water pump good, and do you have underdrive pulleys that would slow the pump?

I think JimN's got some good points there - your shroud, if you changed to a flex fan, should have the fan about 2/3 inside the shroud and 1/3 outside. Since you're probably goint to switch to electric, that won't matter though.

I wouldn't use a single fan unit, I would get a higher cfm dual fan - like Flex-a-lite's Black Magic. It moved more air and you could adjust the temp it came on at. The dual fan will pull air through more of the radiator surface. There's some real good tips here (do a search) on a great fan setup to use - I believe it was off the ford windstar vans.

To answer your question, the electric should work better than the flex fan at idle, depending on how many cfm your flex fan pulls at low rpms. The electric is either full on or full off.

Here are some references I found: http://www.chevelles.com/forum/Forum23/HTML/000435.html http://www.chevelles.com/forum/Forum23/HTML/000636.html http://www.chevelles.com/forum/Forum23/HTML/002666.html


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What, me worry??

[This message has been edited by Xtreme70SS396 (edited 02-09-2002).]

Check out my cooling forum at www.inccn.net/techforum.htm (http://www.inccn.net/techforum.htm)

You can get electric fans to cool your big block just fine. One poster did point out the wattage issue. Most of these high output fans require in the vicinity of 25 amps at 13.5 voltsdc. A relay is a must with a thermosensor.

Try www.derale.com (http://www.derale.com) and http://faninfo@spal-usa.com/html/dampframe.htm for more on electric fans. Both of these brands are excellent fans and make fans for OEM applications as well.

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Steve Jack - ConceptOne Pulleys and Brackets / Engineering & Marketing Technologies

[This message has been edited by HOTRODSRJ (edited 02-09-2002).]

ok, my turn, i don't know if you know me but im pretty famous for my info on the Dual windstar fan, check my page below, i've got pics, etc. it's clean and keeps my 454 below 180* in 100* texas weather, with the a/c on!!! im updating the wiring diagram but can't take too many pics because the car is in the paint shop (been there for 7 weeks or so) but next week i'll be finishing the wiring changes. (currently im running 1 fan off 2 relays parallel, they NEED them or will burn up the relays, so 4 30amp relays work great, http://www.chevelles.com/forum/biggrin.gif i'll do some updating tonight but check my page for what i already have...

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1970 SS396 AKA 454/4spd
My Chev-Hell Page (http://hometown.aol.com/jnkb2cool/home.html)
GOLD Member #783
Metroplex Muscle
Ft.Worth, Tx
(OO=ss=OO)

Why in God's green earth are you going to run 4 X 30 amp relays? If you are thinking what I think you are thinking it won't work.....or at least it won't last.

The inductive surge thru the circuit will batter one relay that is the fastest and lowest impendance look-in, and therefore eventually contact failure will happen if you REALLY have the current to need 4 relays.

Are you aware that you can purchase similar automotive relays that are rated at 70amps continuous. I suggest you give it a try. Try www.newark.com (http://www.newark.com) and look at their automotive relays....

Or specifically http://www.newark.com/product-details/text/cd119/60873.html

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Steve Jack - ConceptOne Pulleys and Brackets / Engineering & Marketing Technologies

[This message has been edited by HOTRODSRJ (edited 02-09-2002).]

[b/]chev-hell[/]b, if you have any of the dual widstar fans for sale please contact me via email. I remember you having them a while back, if you still have some or will sometime soon I would like to buy a set-up from you. Thanks.

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'70 SS 396
4spd, 4.10's and a smile
TC# 1341
Beaux

Everytime I think about where I want to be I realize its never where I am.

ok, the 2/fan relay is for initial start-up mainly yes, 1 will start a millionth of a second quicker, but, the initial start up is a few seconds long, and running 2/fan will reduce wear/heat on either, plus im running them on sockets and at the same time left the lead wiring the exact same legnth and soldered them together at the o-ring connector.

midnight, nope, don't have any, haven't for a while (just took that off my web-page a few minutes ago as i updated it). but if i can find 1 i'll let ya know, i have 2 but they are just for parts (motors are bad) http://www.chevelles.com/forum/frown.gif

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1970 SS396 AKA 454/4spd
My Chev-Hell Page (http://hometown.aol.com/jnkb2cool/home.html)
GOLD Member #783
Metroplex Muscle
Ft.Worth, Tx
(OO=ss=OO)

CHEV-HELL, with all due respect,.. me thinks that you don't understand what I was pointing out. May I elaborate please, I am trying to help you, whereas I humbly submit to you that I use to design DC bus systems in Nuclear Power Plants as a professional, and would like to make a few points that definitely can help aleviate future issues. I would like to respectfully point out why you may be your own worst enemy here as far as building reliability and capacity for your switching circuit for you fans with this parallel relay idea.

I am going to try to explain this without writing a book, but enough information to help you out here. Please bear with, I promise not to get toooo techy.

I do not know what the dual Winstar fans require as far as wattage/amperage is concerned, but if you are burning down 30 amp relays then I would suggest that these are simply not rated high enough (both in contact rating and probably breakdown voltages) for the application....and paralleling now several of them for making up for the lack of ability to handle these issues is a bad idea.

My estimation is that the fans are hefty fans that may take up to 25+ dc amps a piece continuous, nothing wrong there...great workhorses. If that is the case, then a rating factor of at least 150% of continuous current is a good/typical safety margin and acceptable benchmark for any controlling element in a circuit for these types of applications. In that case, you should be using at least 40 amp continuous rated relays, which are also readily available at the page(s) I pointed out earlier. Each fan circuit should be divorced from the other (we will get to the reason why in a moment) with separate feeds from a terminal and separate fuses and relays. This is the most reliable and wanted design. The control circuit is obviously paralleled, no problem there either as long as the relays are co-located. If you parallel relays for the fan(s), then EACH relay you parallel should have the capacity (150% of continuous) of completely operating a fan entirely on its own. I am assuming that your plan here is to parallel these relays to in affect make up for any deficiency in one. There is nothing wrong with paralleling relays that are both capable of taking the full load, all the time, for the sake of redundancy as long as it's designed right, but contrary to what one would think, if you parallel two relays that ARE NOT capable of taking the entire wattage/current etal in standalone mode, then the circuit is only as reliable as the fastest pull=in and/or slowest drop-out time relay. In fact, you are actually adding components by paralleling them that increase the MTBF (mean time between failure)of the circuit. This circuit is best served by completely divorced circuits and a single relay that will do the job, in my opinion. It actually will live longer this way.

Now to get to the part about relay operation science. Your statement about current in-rush on startup is only a small part of the problem. There is in-rush current and it's not a 1/1,000,000 second operation either, but rather long period of time electrically. Actually, in a motor circuit or high inductive circuit, the current inrush leads the voltage big time and is at the highest point as soon as the contacts make (hence an inductive spike)....not over the seconds that the fan physically will take to get up to speed where the current actually decreases. I have seen and worked with relays costing thousands of dollars not capable of the timing collaboration that you state whereas these automotive relays are slow speed by electrical switching standards. They are electo-mechanical behemoths that have a pull-in and drop-out time that is relatively long and moreover impossible to get close in concert by electrical standards believe it or not, for any two to closely match in my experience, better yet relays that are from Radio Shack etal. So, whether it's turn-on or off, there is an inbalance that you cannot control with the system (inherent to the design of the relay) that you have designed. One relay (the fastest in pull-in) will take the brunt of the front-in induction spike and the slowest drop out will take the back end beating when the circuit is turned off.....and this could be the very same relay by the way. You don't know. None of these have any pull-in or drop-out accuracy to any great extent...just windows of timing I am quite sure.

As I said, the power surge when turned on is a factor, but the induction spike of voltage and current when these fans are turned mainly off and/or cycled is the real relay/contact killer here. Because you have two relays in parallel, only the slowest one (which means the contacts of the slowest one will take all the beating) will take the winddown currrent and voltage of the fan motor when the contacts are last opening and the current is trying to going away. What actually happens is the fan motor tries to keep the current constant and through rotational inertia and/or better yet, windmilling which can produce current/ voltage on its own as the contacts open. Motors act like generators in this mode. The turn off can be and usually is a huge spike. The slowest relay contacts open and in that small time period will try and extinguish the flow of current only to find as the contacts open there is a voltage spike that creates a big spark as the contacts get farther apart and therefore representative voltage of over several hundred volts dc can be present under these conditions. This is the killing force that eats up the weakest relay because it is not designed to take such abuse. The voltage spike along with the current kills the weakest relay contacts over many of these spike filled operation. This scenerio, by the way, is normal operation for a relay contact life. YOu just have to select the proper equipment to go with and/or design spike suppression circuits that help out. The fans where simply too much for the individual relays themselves in your case, however as stated, designing a circuit with relays that won't stand on their own is asking for failure again eventually.

This is why I suggested the 70 amp relay outlined above and they are commercial grade and relatively inexpensive. It can be used indigneously on each fan and will take anything you can throw at it, moreover, it will not fail, I have installed many of these in like circuits requiring far more current. I guarantee it!

I hope you take this with the spirit that it was meant...to help.

BTW, I went to your page and was impressed with the clean up job under the hood you did as well as the format and webpage itself. Good job there. I also studied your wiring diagram and am hoping that you are using some sort of breakers, fuses for protection even tho not mentioned or diagramed.

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Steve Jack - ConceptOne Pulleys and Brackets / Engineering & Marketing Technologies



[This message has been edited by HOTRODSRJ (edited 02-11-2002).]

Hey chev-hell, what are the diminsions of those fans? I have sufficient cooling, but I can't stand the way it looks.

<BLOCKQUOTE>quote:</font><HR>Originally posted by chev-hell:

midnight, nope, don't have any, haven't for a while (just took that off my web-page a few minutes ago as i updated it). but if i can find 1 i'll let ya know, i have 2 but they are just for parts (motors are bad) http://www.chevelles.com/forum/frown.gif

<HR></BLOCKQUOTE>

OK, thanks I appreciate it. http://www.chevelles.com/forum/cool.gif



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'70 SS 396
4spd, 4.10's and a smile
TC# 1341
Beaux

Everytime I think about where I want to be I realize its never where I am.

A great fan set up is a Spal dual fan for your big block. They are makers of OEM fans for the likes of BMW, Volvo, and other popular brands. Their fans are notorious for CFM production.

Go to www.spal-usa.com (http://www.spal-usa.com) for more info. The dual 11" fans will cool just about anything.

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Steve Jack - ConceptOne Pulleys and Brackets / Engineering & Marketing Technologies