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 electric fan + lightweight mechanical
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69warbird
Tribal Scout

USA
22 Posts

Posted - 13 Jun 2012 :  11:42:52 AM  Show Profile  Reply with Quote
Currently i am running a Flexalite Black Magic(tragic) 150 fan and a 26x18in aluminum radiator on my firebird 400 muncie car. It runs fairly cool, about 190 tops. That fan does push a good bit of air through the radaiator at idle, problem is the shroud only covers about 70% of the core. Just doesnt seem like enough for the primary fan in traffic in the summer heat.

As extra insurance, in case the black tragic fails, would a supplemental super lightweight 18in flex fan help at all? or would it just rob power? There would be zero room for a fan spacer so it would not be very close to the radiator and a shroud for it would almost be out of the question.

several other ideas ive had included making a better shroud for the black magic...this could be done with very careful cutting around the control box and stock integrated shroud and using something like summits' adjustable fan shrouds. They are only about 50 bucks. more time consuming but less cost. Would also probably have to fabricate new mounting brackets for the fan.

Or i could just ditch the electric fan altogether, get an 18in flex fan w/ the biggest spacer i can find and a factory shroud and call it a day. (biggest investment)

Any recommendations?

GtoGuy32
Cochise

USA
842 Posts

Posted - 13 Jun 2012 :  7:21:04 PM  Show Profile  Reply with Quote
Mechanical Thermal Clutch and 18" rigid fan.

It's quiet, virtual bullet proof, cools when it needs to, and is more forgiving on the water pump.

Plus it is good for freeing up a couple ponies over those flex fans (so I have heard)

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69warbird
Tribal Scout

USA
22 Posts

Posted - 14 Jun 2012 :  12:41:41 PM  Show Profile  Reply with Quote
thanks for the advice. I've already put so much effort into running that electric fan that i will probably keep it. When its working right, it does move a lot of air. I see nothing wrong with staying right around 190-200F.

according to flexalite's instructions, if you use any other manual switch than their brand, for some reason you are supposed to disconnect the switch ground (dash light) or else, in their words, this "will cause the unit to fail." this is probably part of the reason why i have been experiencing intermittent shut-off of the fan. im constantly constantly watching all the gauges because of that issue.

If i cut out the stock integrated shroud, extend the motor wires and re-locate the control box then i can make a better shroud out of that summit u-cut-to-fit shroud kit and be done with it.

Edited by - 69warbird on 14 Jun 2012 12:44:42 PM
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Chicagogoat
Cochise

USA
823 Posts

Posted - 14 Jun 2012 :  11:53:19 PM  Show Profile  Visit Chicagogoat's Homepage  Reply with Quote
I've had that same fan for years and now on a new motor with the same cheap universal griffin radiator and I will say that it does a really good job at keeping the temp at bay. If you are running a little hot in traffic that's not unusual. Here's some good reading that may be of interest http://www.griffinrad.com/tips.cfm

Also if the high powerdraw on stock wiring and alternator is causing problems, I strongly recommend a variable speed control like the one flexalite makes which eases power spikes by ramping up the power to the fan to match temp demands. I wired my electric cooling system and ignition into one control module activated by a painless 3 circuit relay. Wiring was straight forward, the same activation wire from the ignition switch that powered on the MSD, I wired to power on the the relay which sends fused power to the 6AL, elec w.p. and variable fan contol. If you want a single relay to activate the fan circuit then you need a single pole relay rated at 30 amps and 10 gauge wiring. Ground it straight to the battery since its closest to the fan and preferable. 30 amp Fused power through the battery or alternator/starter junction. You should get no hotter than 195 at idle in traffic with that fan at full power. What kind of alum rad do you have? Dual core 1" or 1 1/4" rads will run away with a street Pontiac motor.

Pure Pontiac: learn it, live it, love it!
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69warbird
Tribal Scout

USA
22 Posts

Posted - 15 Jun 2012 :  1:16:29 PM  Show Profile  Reply with Quote
thanks for the info. When that fan is working right, temps never go over 190 even in traffic. I'm really happy with that. Im not sure what type of radiator it is, it was a univeral aluminum radiator bought from VSI. probably a 2 row. Also upgraded to a 100 amp alt. to keep constant current flowing and also added a painless 30a relay and a manual switch. Those items made a world of difference, rarely will the fan cut out, usually happens after a 30minute ride out to the shop. I'll disconnect that wire and see if any change is apparent.
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Vanmor
Cochise

USA
573 Posts

Posted - 25 Sep 2012 :  7:21:58 PM  Show Profile  Visit Vanmor's Homepage  Reply with Quote
I just fired up my fresh rebuild and boy did it run hot. My clutch fan was spinning but not cooling. I had replaced my old four row radiator with a two row aluminum. I was thinking the wrong choice had made in radiators. I had to spray the radiator down with a hose to keep it at 190 to 200. I pulled the thermostat out but that didn't help. I went to NAPA and bought a new clutch for the fan for $34 and mounted the top and bottom shroud. What a difference!! Now the car sits there at 150 at idle all day. The fan is barely even with the edge of the shroud and it still cools great. Keep in mind that this is with the front end off the car and the thermostat still out. Everyone was telling me to get an electric fan. I'm sure they work well, but for now, I'm staying with the stock clutch fan.

"A man has got to know his limitations." Dirty Harry
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cortcomp
Coyote

USA
5338 Posts

Posted - 25 Sep 2012 :  7:26:39 PM  Show Profile  Visit cortcomp's Homepage  Reply with Quote
Van,

what a big difference right? When my clutch looked like it was leaking bad, i replaced it. that and the timing change took me from 210 down to 175 lately! I think the timing change did more though.

I do notice around my carb and fan that there's like a fine dust crud from what i think is the fan clutch. It's a new hayden super duty, other was hayden heavy duty. I want everything to stay clean, but shoddy quality parts are working against me -_-
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Chicagogoat
Cochise

USA
823 Posts

Posted - 25 Sep 2012 :  9:55:22 PM  Show Profile  Visit Chicagogoat's Homepage  Reply with Quote
Also, a fresh motor will run a little hotter than you expect, as others have reported. My rebuilt 455 was running a little hot in the first couple hundred miles up to 200 in traffic. Being overly concerned I checked the fan's amp draw many times and it was at full power over 20 amps and that flex-a-lite fan pulls so strong on high. Now I can cool it to 175 steady even during the brutal heat earlier in the summer it never got above 190.

Pure Pontiac: learn it, live it, love it!

Edited by - Chicagogoat on 25 Sep 2012 9:58:27 PM
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Vanmor
Cochise

USA
573 Posts

Posted - 26 Sep 2012 :  04:37:11 AM  Show Profile  Visit Vanmor's Homepage  Reply with Quote
cc, I don't know who made the clutch but I always get good service from NAPA parts. I bought the cheapest one but it seems to be working fine. Hayden is supposed to be a really good product. You may just be moving so much air now that your getting all that dust associated with it.

Clutch fan, flex fan, electric fan or fans..... I think they all work and you just have to use what you like.

"A man has got to know his limitations." Dirty Harry
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cortcomp
Coyote

USA
5338 Posts

Posted - 26 Sep 2012 :  09:30:15 AM  Show Profile  Visit cortcomp's Homepage  Reply with Quote
I just don't like the noise and look of electric fans. They're great for economy (that's why used in new cars) and less HP drag, but they stick out in an engine bay in an older muscle car (my opinion) and the ones moving a ton of air can be really noisy cruising through a show.

Also, i always feel like the car is winning if i give up and put electric fans in instead of finding the issue that's causing the heat (in my case, clutch and timing, and probably still mixture too some). Some can't get cool no matter how much tuning they do, and electric fans work for them. I don't think i'm putting out that level of power that an aluminum rad and stock fan couldn't handle.

For those asking, the cheap ebay radiator fit and worked well! (american eagle i think) Use 2 core shroud and mounting rubbers. I painted the ends of the tank black, and you almost don't even notice it.
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