Thoughts on Mechanical Fan Please - Chevelle Tech
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post #1 of 51 (permalink) Old Aug 24th, 18, 1:25 PM Thread Starter
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Thumbs up Thoughts on Mechanical Fan Please

71 Chevelle 497 (600 hp) 295/295 cam. TH400 gear vendor.......Have had challenges blowing fuses with my electric flexalite system. And I never felt that the system cooled things the way I liked. Anyway, read a lot on this site from Scott and others regarding the benefits of mechanical fan and have been researching.

What do you think of the below approach:

Flexalite 4818. 7 blade no fan clutch

Champion Shroud (including insulation on edges)

Thanks
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post #2 of 51 (permalink) Old Aug 24th, 18, 2:45 PM
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Eric
 
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Re: Thoughts on Mechanical Fan Please

Believe it or not, I use an APDI/PRO 8010322 Radiator - plastic tank/ aluminum single row 1 1/4 core with Flex-a-lite 1818 fan (same as the 4818 but blue) mounted 1 inch from the radiator, no shroud. Keeps my 468 cool even in 100+ degrees here in Texas. The problem is mechanical fans cfm are not advertised.

Your just jealous because you can't hear the voices!

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1963 Plymouth Fury 440/Torqueflite
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post #3 of 51 (permalink) Old Aug 24th, 18, 2:53 PM
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Re: Thoughts on Mechanical Fan Please

Isn't that the fan Mark Jones likes?

Jim

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post #4 of 51 (permalink) Old Aug 24th, 18, 3:15 PM
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Bill
 
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Re: Thoughts on Mechanical Fan Please

That looks like the flex fan that I use. I'm not sure of the part number. I use it with a stock fan shroud and it never gets over 195 on the hottest days while sitting in traffic (4 core & 454). I would suggest a stock fan shroud over the one you have pictured. That one is just a finger guard. It will not direct air thru the radiator.

1969 Sport Coupe SS Tribute Cortez Silver 454 400TH
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post #5 of 51 (permalink) Old Aug 24th, 18, 3:20 PM
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Re: Thoughts on Mechanical Fan Please

I am all in favour of using an Mech Fan plus full Shroud for a car that has a 3 or 4 Row Core Rad
and if the Engine is above Idle Speed while in Stop & Go Traffic

esp if there is a A/C Condenser or Trans Cooler in front of the Rad
as you need something that can pull Air thru a lot of Fins

Efans with a Full Shroud are more Efficient when the Car is in Stop & Go Traffic since they are at their Max Air Pulling when on
a Mech Fan's Air Pulling is dependant on the Engines RPM speed that is why their CFMs are not Listed

I have had a Mech Fan without a Shroud on my Car's SBC with a old Stock Rad and it worked okay



When I went to a BBC there was very little room for a Mech Fan
so when I put in the BBC and a new Alum Dual 1.25" Row Core Rad with a small Trans Cooler in front of it





I attached a SPAL Dual 11" Efan/Shroud Setup with 12 Hwy open Air Flow Rubber Flappers



that keeps my BBC running Temps of 170* on the Hwy with just none or one Efan on
and in the City in Traffic at 170-180* with both Efans on plus at the Track doing back to back runs down the 1/4
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post #6 of 51 (permalink) Old Aug 24th, 18, 3:21 PM
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Re: Thoughts on Mechanical Fan Please

I ran one like that on my 69 for many years with no overheating but it's just a 30 over 396.

A little loud at engine rev up though.

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post #7 of 51 (permalink) Old Aug 24th, 18, 4:20 PM
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Re: Thoughts on Mechanical Fan Please

Nothing wrong with that fan. I have had the blue version on my car since I have owned it (22 years) and I have not had any cooling problems at all (it was on the car prior to me owning it with no issues either - my mom gave me the car in 1996 and that fan was on it when she was still driving it). I am running it with the factory shroud, so I don't know how it will perform with an aftermarket one.

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Last edited by WakkoWarner; Aug 24th, 18 at 4:41 PM.
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post #8 of 51 (permalink) Old Aug 24th, 18, 4:32 PM
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Re: Thoughts on Mechanical Fan Please

In my 70-with a 468 I run a 100% stock 1970 Vintage cooling system, AKA= VO-1. It uses the large rad. support, along with a stock 4 row C./ Brass Rad. A fan clutch for a mid 80s Burb ( fits a 772 blade perfect). & a 3947772 Fan blade along with a stock 811-TX water pump
& stock shroud.
My one owner LS-5/M-22 has the same system and never got hot in my 48 years of ownership. I built my driver to match.
One item a lot of folks miss is Removing the SUPERHEATED AIR from the engine bay. The bottom line is THIS and THIS only! How much Cu. Ft. of AIR per Min. are you moving through the heat exchanger and the engine bay ! Not only does the 3947772 fan blade and clutch draw a lot of air through the heat exchanger it also REMOVES the hot air from the engine bay.
Another reason I like a clutch on the fan blade, The G.M. and other stock fan clutches ( Ford & Mopar) do not go over 2500 / 3000 RPMs.
In the late 60s & early 70s,,, ALL of the big THREE ran Multi blade fans and clutches on the big H.P. factory engines. Mopar was the first. The first 426 Hemis used a multi blade fan and a clutch, WHY?
The Hemi gained 17 H.P. with a clutch fan over the direct drive blade.
The factory type clutches and other good clutches are " Free Wheeling " most of the time and the only spin up to 2500/3000 grand and they free wheel. The only reason to have a fan is ,,, When the car is STATIC or near STATIC do you need a fan.
Many good ideas to keep your engine kool. Do your homework then...... Do what makes you happy.
Keep this in mind when you hear " New and Improved ", Get ready to hang on to your WALLET !
Bob
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post #9 of 51 (permalink) Old Aug 24th, 18, 10:40 PM
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Re: Thoughts on Mechanical Fan Please

I would run a stock Chevelle shroud and the flex fan that fits the opening allowing 1' clearance all around. You need a spacer with that flex fan. You want it so sit half in and half out of the shroud for maximum cooling. Too close causes turbulence inside the shroud, to far it pulls some air from behind the shroud instead of through the shroud.

I currently run a 1818 flex fan and a 1.75" spacer with a 70 fan shroud on a 70 454 no a/c 3 core and it stays cool all the time. I have 2" clearance from the radiator and the fan is half in and half out the shroud. Surprisingly it's not noisy either. The fan you are looking at is a staggered blade type. It is supposedly a design that decreases fan noise.

The 71 and 72 shrouds cover the entire radiator and the 70 only covers about 3/4's of the radiator. I forgot the year of change but in 71 or 72 they went with a 19 inch blade that is made from unobtanium that ran through a fan clutch. (The original GM 19 inch blades are hard to find) Flex-A-Lite a 19 inch flex fan that will fit the larger holes in the later shrouds.

I can't knock the stock 772 an HD fan clutch. If my fan clutch didn't start leaking I would still be running it. The flex fan ended up on the car because it was hanging on the wall.
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post #10 of 51 (permalink) Old Aug 25th, 18, 11:15 PM Thread Starter
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Re: Thoughts on Mechanical Fan Please

Thank you all! Went to local speed shop today - ran into guy with same problem in his 396 El Camino. On the back of his pickup, he literally had the fan above and a fan with a clutch.... he didn't have luck with either so he went electric. Since I already have electric (fuze blowing and loose wire problems) - by the way I ran 185 40 miles in 84 degree La temp this morning, so not bad......anyway, we are going to add a seal between the radiator and the fan and replace the fan wiring with a relay kit... I'll keep you posted.
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post #11 of 51 (permalink) Old Aug 26th, 18, 5:53 AM
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Re: Thoughts on Mechanical Fan Please

Just be careful with the blades on the Flex a Lite S/s flex fans. They are sharp!

More cooling tips & myths dispelled:

Stewart Components
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post #12 of 51 (permalink) Old Aug 26th, 18, 1:56 PM
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Re: Thoughts on Mechanical Fan Please

Fans... So many different scenarios that its difficult to say what's best in every situation... Its never truly "apples-to-apples"... Not only the local climate, but things like tuning (lean mixtures and ignition timing can cause overheating) along with the size and type of core (some cores are more restrictive to airflow than others, while some others may provide more coolant contact with the tube surfaces (needed for heat transfer) as well as water pump impeller design, flow and pulley ratios.

IMO, work with what you have first. Make sure its all properly working, before throwing it all out and starting over from scratch...


IMO, IF choosing a mechanical fan, then why NOT use a clutch version? And of course, an full-coverage (stock?) shroud. If you read through Scott's writing, he usually suggests the stock GM 7-blade fan and the Hayden HD clutch...

I have had cooling issues on various Chevelles over the years, and each one seemed to respond to different methods and parts selection.


Personally, I now replace the water pump with a well engineered "high flow" version (I have had excellent results using the EMP/Stewart Pumps), as well as a quality thermostat. naturally, a clean radiator helps.


My last Chevelle used the Flex-a-lite dual fan (#498?) with integral, full coverage shroud, with pressure relief flaps. It fit the Summit/Northern "direct replacement" aluminum radiator well, and with the Stewart pump, my cooling problems were solved. While my A/C wasn't functional, the condenser remained in place ( a restriction to air flow). The car typically would not go over 185 in traffic (using only one of the fans). If it did climb to about 195-200, then the second fan would kick on, and bring temps back down. I have seen temps up to about 200+, but that was with 100+ degree days stuck in heavy stop and go traffic (a few times at Hot August Nights in Reno), but the second fan always seemed to bring the temps down quickly) I was using individual adjustable Derale fan controllers and relays for the fans. On the highway, the temps would often drop below 175 (gauge sender in the intake manifold, NOT in the head).

I had indicator lights that lit up when the fans were energized, as well as a "calibrated" gauge (upon initial warm up, the gauge would rise to 180-181 degrees (on the gauge), and then drop when the Thermostat initially opened. once "warmed up", the temp stabilized.

So when people blindly state that electric fans are no good, I usually disregard further cooling "advice".


I also live in an area where I am not worried about freezing (maybe 15 nights a year with outside temps under 32 degrees, but my attached garage never gets that cold), so I ran straight water (distilled) with Redline Water Wetter for corrosion/lubricity. Water is a better coolant than "coolant" (at least than Ethylene Glycol). As a side benefit, I have had leaks before, and always hated the sticky mess that EG coolant made... Had a friend (hood-less car), that blew off the top radiator hose at a car show once... What a mess, as the coolant sprayed out on 4-5 other cars... Luckily, no one got burned...
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post #13 of 51 (permalink) Old Aug 26th, 18, 2:43 PM
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Re: Thoughts on Mechanical Fan Please

Quote:
Originally Posted by Skier_Bob View Post
71 Chevelle 497 (600 hp) 295/295 cam. TH400 gear vendor.......Have had challenges blowing fuses with my electric flexalite system. And I never felt that the system cooled things the way I liked. Anyway, read a lot on this site from Scott and others regarding the benefits of mechanical fan and have been researching.

What do you think of the below approach:

Flexalite 4818. 7 blade no fan clutch

Champion Shroud (including insulation on edges)

Thanks
same fan im running on my bb 427 66 chevelle no heating problems. just make sure u run a fan shroud and seal around the edges
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post #14 of 51 (permalink) Old Aug 26th, 18, 7:31 PM
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Re: Thoughts on Mechanical Fan Please

One fan setup to consider is the dual fans from an early 2000's ford escape. I have that setup on my '71, and it keeps my 468 at about 180 in stop and go traffic in the summer here in central AL. I paid less than $40 for it from a junkyard. It pulls 46 amps continuously; it's not something to half ass the wiring on. For a relay, I'd advise you to go to a golf cart store and buy a big 12V relay. Mine looks like a ford starter solenoid and is rated at 80 amps or so. Do NOT just get a starter solenoid-they aren't rated for continuous duty and will literally burn up. You need a snubber diode in the circuit to protect the relay contacts from excessive arcing that occurs when the fan(s) are turned off. Turning a dc motor off generates a sizeable voltage spike of opposite the polarity than was applied when the motor was running. A snubber diode installed correctly does not conduct current when the motor is running (it's reverse biased in this case) but shunts the turn off voltage spike to ground harmlessly, keeping the relay contacts from being exposed to it.
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post #15 of 51 (permalink) Old Aug 26th, 18, 8:34 PM
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Re: Thoughts on Mechanical Fan Please

Quote:
Originally Posted by Gtogeoff View Post
Just be careful with the blades on the Flex a Lite S/s flex fans. They are sharp!

More cooling tips & myths dispelled:

Stewart Components
I agree in regards to the fan blades! Also some very interesting reading on the Stewart site. Thanks for the link.
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