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 flex fan vs. clutch fan
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craiglemans
Buffalo

59 Posts

Posted - 25 Jul 2008 :  1:48:08 PM  Show Profile  Reply with Quote
I've been battling a cooling system issue for a while. My car would go up to 210+ on the highway and would run around 190-210 around town. After reading some stuff on the PY site it seemed like guys were having issues with fan clutches. Sure enough, after thinking about it, my problems all started when I "upgraded" from my flex fan to a clutch fan with a brand spakin' new heavy duty clutch.

I went back to the flex fan and my highway temps are back down to 180 (180 high flow t-stat) and 195 at lights. It turns out my old flex fan is a 7 blade 19" bohemoth that runs VERY quite (it looks like the caddy fan that's on ebay for $8 right now). No fan noise at idle or highway speed.

I know there are a lot of pontiacs out there that run hot, you guys might want to at least look into the fan as I never would have thought that was the source of my problem. I guess the point of this, just because they are new parts, don't always assume they aren't a source of your problem. Apparently that new fan clutch had it's t-stat set @ 210 and was defeating the t-stat in the engine.

Cobrabill
Talking Dog

Aruba
3109 Posts

Posted - 25 Jul 2008 :  3:55:58 PM  Show Profile  Reply with Quote
Sorry,dude,but there is some part of the equation missing.A PROPERLY shrouded factory clutch fan is SUPERIOR to ANY flex fan on the planet.Also running hot is NOT a Pontiac trait.In 42 years,i've never had a Pontiac that ran hot.

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mike mcarthur
Pony that Jumps

USA
2475 Posts

Posted - 25 Jul 2008 :  10:07:17 PM  Show Profile  Visit mike mcarthur's Homepage  Reply with Quote
Ditto what CB said.

It's the stuff you learn after you know it all that's important
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Phil
The Great White Buffalo

USA
7170 Posts

Posted - 25 Jul 2008 :  11:36:25 PM  Show Profile  Reply with Quote
Double Ditto! I ran flex fans in the 80's before I wised up. I hated the loud "hair dryer" sound and I got sick and tired of putting old crew socks on my hands and arms when working around it.

Something is amiss with your problem. Either you have an issue with the position of the fan or perhaps you have a bad/wrong clutch.

Keep poking away at the problem and you will figure it out. That is, unless you really LIKE the flex fan.

Bowties are for Pee-wee Herman. "Chevy": even the name sounds cheap, but not as cheap as your Pontiac will be with an LS transplant.
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Matt H
Cochise

USA
310 Posts

Posted - 26 Jul 2008 :  03:02:10 AM  Show Profile  Visit Matt H's Homepage  Reply with Quote
May want to check the temp gauge for accuracy , by using a handheld pyrometer.

Matt H
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RayK
Cochise

USA
925 Posts

Posted - 28 Jul 2008 :  10:25:10 AM  Show Profile  Reply with Quote
I ran a non air 70 GTO fan for years on the 455 without any issues, then when we put the 670 heads on it and added some timing it started running hotter, so i switched to a 7 blade clutch fan and she runs about 180. perfect! Clutch fan is the way to go.

1969 Firebird 461, #62 iron heads, Comp roller, Performer RPM, Q-Jet Turbo 400 w/ Continental converter. GM 8.5" 10 bolt with 3:73 gears.11.50's@ 119+ MPH
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craiglemans
Buffalo

59 Posts

Posted - 28 Jul 2008 :  11:38:19 AM  Show Profile  Reply with Quote
CB, "dude" am I missing some sarcasim here?? Running hot is not a pontiac trait!?!?! Are you kidding me!!?!?!? There's an entire forum about heating and cooling and 20 page link about adjusting the divider plate on the PY site. Cooling issues seem to be prevelant with all brands, or at least that's what I hear at the shows I go to. Hence a booming aftermarket demand for aluminum radiators.

All I can say is take for it's worth. I never would have thought that running hot on the highway was a fan related problem. If you don't beleive it, then don't try it, it won't hurt my feelings.



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Cobrabill
Talking Dog

Aruba
3109 Posts

Posted - 28 Jul 2008 :  4:49:29 PM  Show Profile  Reply with Quote
No i am not kidding.And no sarcasm.Running hot is not a Pontiac trait.If the "Pontiac" in question is running hot,then there is something wrong with it.
Again i will re-iterate:NO Pontiac on the planet that is mechanically sound(no race cars)will have an over-heating issue.This is NON-debateable fact.I don't care how many pages are written on PY or any other site for that matter.

There is a "booming market for aluminum radiators" because aluminum works better.Better as in 30% better heat extraction than brass.

Don't worry-i won't try it.No need to.I've been wrenching on Pontiacs since 1966- i know what works and what doesn't.Flex fans don't.


Edited by - Cobrabill on 28 Jul 2008 4:54:43 PM
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Brian R
Crazy Horse

USA
1669 Posts

Posted - 29 Jul 2008 :  08:40:53 AM  Show Profile  Reply with Quote
I have been running a flex fan for years - never overheated. 71 Lemans, 400, #16 heads. That said, it does get on the border around 210 when sitting in traffic. Because of this I am going to go with a clutch fan for next summer to see if it helps.

As far as Pontiacs running hot - I remember well in the 70's and early 80's when sitting in traffic on hot summer days on Cape Cod - 3 out of 4 cars pulled over with steam coming out were Firebirds and Cameros - every weekend for years. These were still new cars at the time. I am not talking about 1st gen, these were all 2nd gen. Maybe these guys were running the AC while sitting in stop and go traffic which is always asking for trouble on any car - new or old. Friends of mine over the years with Goats and Lemans also run on the cusp as I do. I always thought that Pontiacs needed louvers/baffles of some sort to allow better air flow - as all whom I know have always had to keep a constant eye on the temp gage with Pontiacs. This does not seem to be true with Buicks, Olds, or Chevy's - except 2nd gen Cameros.

That is my experience. This is not BS, just my experience. Does that mean all Pontiacs have the tendency to run hot - from what I have lived - yes. Never the less, I respect Cobra's experience also so I guess we all "know" what we know - "know" being a relative term.

So, either way, a clutch fan IS on my list. My radiator is a stock style rad. If the clutch doesn't bring it down to a more livable temp thus causing less worry - I may consider an aluminium rad.

C-Bill - I am pretty sure we went around and around about this sometime in the past 8 or 9 years so I really don't want to go further.

If clutch and aluminium work for someone - go for it.

BTW - my timing and carburation are not factors in this equation as they have both been gone through many times over the years. My fan placement is as good as it gets - I have used different spacers and settled on what works best for my car.

Edited by - Brian R on 29 Jul 2008 08:44:50 AM
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Cobrabill
Talking Dog

Aruba
3109 Posts

Posted - 29 Jul 2008 :  10:02:34 AM  Show Profile  Reply with Quote
Not debating your experience.But like i've said-i haven't had a Pontiac that ran hot in 42 years.Up untill 1986 that was in NE.Then from 86 untill 2000 it was So.Cal.Then from 00 untill now it's been Tucson.As far as flex fans go-do people have success with them?Yes.Are clutch fans superior in every measurable way?Again-yes.

Were those F-bodies headed towards or away from P-town?(couldn't resist).

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Brian R
Crazy Horse

USA
1669 Posts

Posted - 29 Jul 2008 :  10:56:37 AM  Show Profile  Reply with Quote
Nah, not F-Bodies, those were the Pink Passats...... lol

How do you know P-Town - - hmmmm....??? just kididng
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Cobrabill
Talking Dog

Aruba
3109 Posts

Posted - 29 Jul 2008 :  12:00:26 PM  Show Profile  Reply with Quote
Grew up in Ct.Used to vacation on CC in the mid-60s.Even then it was Fruit-Loop central.I remember asking my mom( i was about 7 at the time)why those men were holding hands.

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mike mcarthur
Pony that Jumps

USA
2475 Posts

Posted - 29 Jul 2008 :  4:31:23 PM  Show Profile  Visit mike mcarthur's Homepage  Reply with Quote
Have to ditto CB again. I've had numerous Pontiacs over the past 20 years and the only one that overheated was a 70 GTO because it had a bad radiator. My 79 400 powered Lemans wagon has been together for 18 years and has never overheated even with the A/C on. I'm in SE VA and it gets plenty hot here in the summer. The only thing I've done is add an electric fan that comes on with the A/C to help the A/C perform better. I lived in Savanah for awhile a number of years ago and had an 81 Firebird with the awesome 265 in it. It also never overheated. I believe it comes down to a properly set up combination of a tuned engine and a solid cooling system, good pump, divider, sleeves, radiator, T-stat, belts, etc.

It's the stuff you learn after you know it all that's important
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Brian R
Crazy Horse

USA
1669 Posts

Posted - 29 Jul 2008 :  4:35:11 PM  Show Profile  Reply with Quote
Maybe it was a whole lot of Chevy guys thinking they knew how to tune a Pontiac ......:)

Edited by - Brian R on 30 Jul 2008 12:54:40 PM
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Phil
The Great White Buffalo

USA
7170 Posts

Posted - 30 Jul 2008 :  11:39:04 AM  Show Profile  Reply with Quote
yeah, Chevy guys think everything can be tuned with a BMFH!

CB, you anywhere near Valencia Road?


Bowties are for Pee-wee Herman. "Chevy": even the name sounds cheap, but not as cheap as your Pontiac will be with an LS transplant.
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Cobrabill
Talking Dog

Aruba
3109 Posts

Posted - 30 Jul 2008 :  12:00:18 PM  Show Profile  Reply with Quote
I'm about 20 minutes from it.

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nyracer
Sitting Bull

USA
167 Posts

Posted - 05 Aug 2008 :  8:52:04 PM  Show Profile  Reply with Quote
I use a flex fan on my 71 lemans with a 350. The clutch and a steel fan is very heavy. I think it wears the water pump bearings faster. I got over 100,000 miles on my last water pump. I also use a 180 thermostat.
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Phil
The Great White Buffalo

USA
7170 Posts

Posted - 06 Aug 2008 :  1:41:57 PM  Show Profile  Reply with Quote
CB, small world indeed.

Bowties are for Pee-wee Herman. "Chevy": even the name sounds cheap, but not as cheap as your Pontiac will be with an LS transplant.
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Cobrabill
Talking Dog

Aruba
3109 Posts

Posted - 06 Aug 2008 :  5:09:47 PM  Show Profile  Reply with Quote
quote:
Originally posted by Phil

CB, small world indeed.




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455 Formula
Sitting Bull

USA
244 Posts

Posted - 15 Dec 2011 :  10:58:54 PM  Show Profile  Reply with Quote
[FONT="Comic Sans MS"]I have studied this extensively....after much work and some dyno testing, I decided on the 7 blade flex fan from a 1968 Lincoln.

One of the first things we learned was the clutch fan takes MORE HP than a flex fan to operate when it is engaged. If the engine is hot, the fan will engage quite a bit, so keep this in mind when you are trying to save HP by using a clutch fan.

A friend of mine named Ben Arnold drove in the 1969 Daytona 500. He tried all sorts of different fans, trying to extract a few extra HP from his 427 Ford. NASCAR teams at the time used a 'flat' 4 blade fan that had no pitch at all for qualifying and a 4 blade fixed-pitch for racing. Even though a fan clutch was not allowedby the rules, they were experimented with and always resulted in a HP loss when engaged.

I run a Robertshaw 160F thermostat in my 1975 Formula. When I used a 7 blade clutch fan and severe duty clutch, the car would run 210 all the time, even when it was only 48F outside. It seems that some thermostatic fan clutches will only engage at fairly high coolant temperatues.

When the 7 blade flex fan was installed, the coolant temperatures would not exceed 175 even on a 100+ day here in Central California.

The 7 blade flex fan is also remarkably quiet.

Shown here is the 7 blade Lincoln Fan.



Here is the 7 blade Lincoln Fan installed on my 1975 Formula.



Here is the 7 blade clutch fan installed on my 1975 Formula.



Here is a shot of the temperature gauge with the 7 blade clutch fan idling on a 100+ degree summer day.



Here is a shot of the temperature gauge with the 7 blade flex fan idling about 30 minutes later on the same 100day.



Note: ALL temps shown verified by digital pyrometer AND mechanical gauge.

I am currently running a 4 row copper/brass radiator from Autozone (part # CU-477) and my car holds about 22 quarts of coolant.

I hope this information is helpful....
[/FONT]
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cortcomp
Coyote

USA
5269 Posts

Posted - 16 Dec 2011 :  10:49:29 AM  Show Profile  Visit cortcomp's Homepage  Reply with Quote
i've had good luck with the 18" 7 blade flex fan with offset blades, quiet, running at 170 all day in most conditions, 80-90 degrees out with A/C on. Just didn't look right.

Switching to a 19" pontiac 7 blade offset pitch fan and hayden heavy duty clutch. We'll see how it does. Car has always ran cool for me switching and playing with different fans, so might be no difference, but a bigger motor going in so we'll see.
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cortcomp
Coyote

USA
5269 Posts

Posted - 16 Dec 2011 :  10:59:50 AM  Show Profile  Visit cortcomp's Homepage  Reply with Quote
http://www.summitracing.com/parts/FLX-1818/

here it is, works great, just don't like the look.
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Blued and Painted
Chief PONTIAC

USA
3370 Posts

Posted - 16 Dec 2011 :  12:13:49 PM  Show Profile  Reply with Quote
I know the question is about fans but COME ON MAN.You guy's are still shook up about CB's last photo opp. Lets fix craigs car. Fans are for around town, stop and go conditions. Not much effect at hwy speeds. Sounds like the Radiator is at the point where its bearly able to do the job. BearGFR had a nice looking Electric fan set up on the black widow. Rob, could you give us some details.


Bull Nose Formula, 461, TH400/ 3.08 8.5 / R44TS.

Edited by - Blued and Painted on 16 Dec 2011 1:39:08 PM
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cortcomp
Coyote

USA
5269 Posts

Posted - 16 Dec 2011 :  1:43:01 PM  Show Profile  Visit cortcomp's Homepage  Reply with Quote
Oh, i know that, the thread is from 2008. But since we were talking fans and i did a lot of playing with different fans, i thought i'd drop my 2 cents in.
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Blued and Painted
Chief PONTIAC

USA
3370 Posts

Posted - 16 Dec 2011 :  2:01:36 PM  Show Profile  Reply with Quote
Cort, You are always very helpfull and I wish you were my neighbor. I just cant see there would be much differance between the 2 fans at 60 MPH. There must be other factors like air temp or traffic conditions witch would still point to a marginal radiator. Craig, give us some details about the radiator


Bull Nose Formula, 461, TH400/ 3.08 8.5 / R44TS.
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cortcomp
Coyote

USA
5269 Posts

Posted - 16 Dec 2011 :  6:28:01 PM  Show Profile  Visit cortcomp's Homepage  Reply with Quote
At highway speed, yes, i doubt there's much of a difference. It's well worth it to get a radiator like this if you're pushing decent power levels above stock....plus, they look good, and with a new radiator, well, it can't be plugged up and corroded, which i think is a problem with used and reman radiators.

http://www.ebay.com/itm/1968-1969-1970-1971-1972-77-LeMans-GTO-2-Row-Radiator-/110793241755?hash=item19cbcab49b&item=110793241755&pt=Motors_Car_Truck_Parts_Accessories&vxp=mtr#ht_3657wt_1270
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AlsCustomS
Tribal Scout

USA
36 Posts

Posted - 15 Jan 2017 :  4:09:03 PM  Show Profile  Reply with Quote
Silly question... should the clutch fan blades be completely inside the shroud ?

What is the S, in Custom S ?
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cortcomp
Coyote

USA
5269 Posts

Posted - 15 Jan 2017 :  5:42:05 PM  Show Profile  Visit cortcomp's Homepage  Reply with Quote
Thread back from the dead!!

Should be about half in half out. However, i have a 327 with it just all inside, and it runs cool as can be. It is a mild 327 though.
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Admin
Ye Olde Webmaster

840 Posts

Posted - 15 Jan 2017 :  6:20:07 PM  Show Profile  Reply with Quote
No. The fan blades are maybe half in half out. About that, in my experience.

"Dedicated to keeping the classic Pontiac engine alive."

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DanM
Buffalo

67 Posts

Posted - 23 May 2017 :  3:49:28 PM  Show Profile  Reply with Quote
My 71 Lemans has run hot since the day I got it. I have to have every single aspect of the coolant system operating perfectly for that thing not to. I'm quite meticulous so please trust me that there's nothing grossly out of line.

Flow Cooler,
4 row radiator.
And in warm weather I had to change my coolant mix to more water and less antifreeze because I would run hot at highway cruise speeds.

Lately Im running hot while idling and driving slow. So I suspect my fan clutch is finally dead.

SO HERE'S THE QUESTION!
Will the flex fan provide more top HP? I figure either a flex fan or new fan clutch with both solve my idling problem. They are the same price. So, the tie breaker will be HP.

Comments please.

P.S. based on previous data (photos from 455 above) the flex fan seems far superior. If the clutch is designed to engage at 190 then of course the car will idle at 190. That's not a bad thing because some people purposely select the 190 degree thermostat anyway. I just don't want to idle at 210 or 230 like I did yesterday.
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cortcomp
Coyote

USA
5269 Posts

Posted - 23 May 2017 :  5:42:33 PM  Show Profile  Visit cortcomp's Homepage  Reply with Quote
what thermostat are you running? Are you sure it's good? Even if the clutch fan engages fully at 190, it's still spinning some when cold, and will help cool at idle. Also, if the thermostat is opening at 160, then the system should stay 160 when driving down the road, the fan isn't doing as much as just road air is when you're up to speed.

Honestly, it sounds like you have a cavitation problem, which is why i'm wondering if you maybe don't have a thermostat at all? Assuming you've done the pump backing plate clearancing trick?

A flex fan would technically be less drag at higher rpms. Thing is, i don't want to spend any time at 4000+ rpms. I could see it on a track car. I'm clutch fan for life, because i like my cars are like 2500rpms at 75-80mph. Check the fans for their high RPM rating too, last thing you want is one coming apart at like 5000 rpm.

If you cannot be dissuaded from a flex fan, i'd suggest the biggest 7 blade/offset blade fan you can. Offset blades help with noise and give you a spot to get your hands in on the bolts. I've used the below and it moves some air, it's a tad over 18". I'm betting you could fit something 19 or 20 in there if you could find it, who knows.

https://www.summitracing.com/parts/flx-1818
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DanM
Buffalo

67 Posts

Posted - 24 May 2017 :  11:21:51 AM  Show Profile  Reply with Quote
Hi Cort.

Yesterday just in the nick of time I ordered the Flex fan you recommended and a spacer just in case. Yesterday I measured the diameter of the current clutch fan because I noticed a "big" gap between the blades and the shroud. problem? nope. 18"ish diameter fan and 21"ish diameter shroud. Seems in spec to me. maybe I really need a 20" fan if such a thing existed.

I very definitely have a 195 degree thermostat. I recently replaced my heads and spent too much time determining and then reconfirming the proper orientation of the thermostat. And I was careful to use gasket sealant and let it dry because that thing liked to leak in the past.

I am not convinced it is good. I've always been suspicious of that thing how it would let the car rise to 220 then "click on" and let it drop back to 195. However it doesn't explain my problem because I can idle and watch the temp gradually rise, then I can roll at a steady low speed and watch the temp go back down. Therefore I conclude that even just a little air flow across my car makes all the difference - for this problem zone at least. If it was the thermostat it wouldn't know the difference between idle and slow crawling along the road.

but in the thermostat's defense my temp gauge will be rock solid at 195 degrees under most conditions (i.e. not idling in summer heat.)

Just this morning I stuck my head in the engine bay, again, and confirmed that there was air-flow at idle. But I gather it just isn't enough air-flow to get the job done. I've had that fan clutch for 20 years. time for a replacement.

I'm thinking of getting a 180 degree "high performance" thermostat if the flex fan doesn't solve my problems.

Finally, I spoke to an engineer at Flexalite. The 1818 is rated at 8000 max RPM so all the blogs fears of it "flying apart and destroying the radiator" are overhyped unless you are racing your engine above 8000. I will rev below 6000 so I will be within the rating.

Also, it takes about 15 horsepower at high RPM. The engineer admitted that a clutch fan will draw less HP IF it is NOT engaged. i.e. if the ambient temp is below 190 then it will not engage.

So, it appears the true long term solution for me is an electric fan, the type that fits in my existing shroud. That will work nicely at idle and also draw essentially zero HP at max RPM. Assuming $100/HP that 15 HP will be more than the $300 electric fan cost. On the other hand I like the idea of the simple and reliable mechanical fan. Stay tuned.
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Steve C.
Crazy Horse

1632 Posts

Posted - 24 May 2017 :  12:19:05 PM  Show Profile  Reply with Quote
It was appropriate the engineer stated the loss "at high RPM". Years ago in a magazine article they tested various flex-a-lite fans, one example: No fan at 2000 rpm 126 hp, with one "big flex" model it was 125 hp. At a high rpm speed the same flex fan was down 10 hp.

A Flex-a-lite Black Magic electric fan driven by the alternator cost 1 hp."

Edited by - Steve C. on 24 May 2017 12:20:46 PM
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Steve C.
Crazy Horse

1632 Posts

Posted - 24 May 2017 :  12:22:08 PM  Show Profile  Reply with Quote
A tid bit if shopping for electric fans...........

There is no common industry standard for rating electric fans. Most companies use a cfm rating, often expressed in free-flow and not when placed behind a radiator. You can never know for certain about different cfm ratings or how a company has rated their fan since they can be tested by different criteria and methods. In comparison between brands using cfm ratings alone is difficult, typically not apples-to-apples
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cortcomp
Coyote

USA
5269 Posts

Posted - 24 May 2017 :  12:26:00 PM  Show Profile  Visit cortcomp's Homepage  Reply with Quote
DanM, what is your initial timing?
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DanM
Buffalo

67 Posts

Posted - 26 May 2017 :  2:05:57 PM  Show Profile  Reply with Quote
My initial timing is 12 to 13 advance. I add in another 20 gradually. 10 more from vacuum. I run ported vacuum.

I'm thinking my hot weather overheating problems are one of two things: 1) too much coolant bypassing through the heater core. I'll put a valve on it to experiment. And most likely 2) worn out old fan clutch not engaging.

My flex fan arrived yesterday. I'll try it out over the weekend. that thing is bad-a@@ heavy-duty well constructed. Speced to spin at 8000 RPM. Now I see why.

Meanwhile I've done quite a lot of research on HP of fans. In my opinion there is absolutely no freakin' way a radiator fan will draw 15 horsepower. I talked to an engineer at an industrial air fan company and the most they can drive an 18" fan is 1.9 HP at 2000 RPM. They aren't used to answering my type of question "how much HP is being used to spin an 18" fan at 6000 RPM?" They instead look up charts of CFM and PSI and blah blah blah in order to spec a motor. He said their pulleys won't even handle the 15 HP.

If you need to, say, ventilate Gillette Stadium in a hurry you could get your hands on some industrial grade fans that use 15 HP motors to run them. Or if you wanted to fly a small airplane around the countryside you could use a 15 HP engine connected to a big fan (a.k.a. propeller)

But this is a fan. Not a wood-chipper. Not 15 HP. No way Jose. I challenge you to find a single fan/blower to buy at a hardware store that comes anywhere close to even 1 HP. Go to the gym and look at the biggest 36" fan and you'll fine it's using a 1/4th HP motor.

2 HP max. Flex or clutch I don't care.

An electric fan will need the same power to move the same air. It's all about CFM and PSI. Of course the mechanical fan has no choice but to spin at 6000 at redline with the engine while the electric fan doesn't so the electric fan has that going for it. But the flex fan and/or clutch fan will max out its CFM and PSI or it will cavitate.

Just my opinion.
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cortcomp
Coyote

USA
5269 Posts

Posted - 26 May 2017 :  2:12:14 PM  Show Profile  Visit cortcomp's Homepage  Reply with Quote
The electric fan will use gear reduction to run it with a lot smaller motor but at a lot slower rpms. If the fan was mounted on the shaft of the electric motor, it'd be more of an apples to apples comparison.

I had my timing set to 10-12 for a bit in a fresh 455. It ran 210 no matter what. never budged. had an new pump, alum radiator, nice shroud and clutch and fan setup. cold out, hot out, idling in the fairgrounds, down the highway. Moved the timing to 15-16, instantly, car always sat at about 190, all the time, no matter what.

I had never before or since seen timing make such a HUGE difference in temp. Try it, it's free and takes 10 minutes.
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Steve C.
Crazy Horse

1632 Posts

Posted - 26 May 2017 :  6:23:03 PM  Show Profile  Reply with Quote
Here is a tid bit taken from a article in Car Craft magazine...

When they used a mechanical fan, years ago many Winston Cup teams use an inexpensive stock four-blade Ford fan. This four-inch Ford fan, originally built for trucks more than 30 years ago, has proven to be the most efficient and economical mechanical fan on the market. Most teams use it for short-track. The type of track often determines what type of fan, for the super speedway most prefer to use electric fans because of the horsepower and fuel-efficiency advantages. In this situation they could potentially gain 15 percent in horsepower and possibly one to two miles per gallon in fuel.



.

Edited by - Steve C. on 26 May 2017 6:24:17 PM
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GtoGuy32
Cochise

USA
839 Posts

Posted - 26 May 2017 :  10:25:37 PM  Show Profile  Reply with Quote
Ive run all types of fans, rigid 4 blade, flex, clutch and now electric fans.

What I can say is a properly setup clutch fan always cooled my engine and radiator the best, with a close second place being the Flex a lite Black Magic fan that Steve mentioned.

Clutch fans are actually not as rough on a water pump as you would think.

If you can run a factory shroud and clutch fan do it.
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DanM
Buffalo

67 Posts

Posted - 27 Jun 2017 :  4:24:42 PM  Show Profile  Reply with Quote
New discovery! for me at least

While driving 90 miles in 80's heat on the open highway of New Hampshire with little to no traffic my 71 Lemans was starting to overheat - 220 degrees or more. This was bugging me for many reasons.

So I slowed down from 79 mph to 73ish mph and the temp dropped below 210. Hmm. So it appears that above 75 mph the aerodynamic drag kicks in such that the power required to push my car through it exceeds the heat removal capacity of my radiator.

And, I figure (with confirmation of lots of internet data) that my fuel economy suffers equally.

Just some food for thought.
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