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Topic: Engine Fan

in Forum: C3 Cooling and Heating Systems


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Engine Fan (1/13)
 11/22/07 12:00pm
bio11
Former Member

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Oklahoma City, OK - USA

Vette(s):
1972 LS5 Convertible,Auto.Targa Blue with Black Interior.


Joined: 4/1/2007
Posts: 432

I am to the point that I have ran the engine a little and everything sounds great but this thing had no fan when I got it. Have had the radiator rebuilt and installed a stewart high flow water pump. I don't know what kind of fan to get. Should I go back with the original with a clutch or a flex fan I need some input. It does not have a/c. It looks like the original was a 17 1/2"  5 blade. what are the pros and cons of going with a 7 blade.
 
Thanks
Lonnie
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Engine Fan (2/13)
 11/22/07 1:41pm
rearn2go72
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Bladenboro, NC - USA

Vette(s):
1972 conv., sunfire yellow, blk interior, blk vinyl and convertible top. Off frame restoration with American Speed 383 stroker engine producing 500hp plus a 200hp NOS system. MSD ignition. Hooker super competition headers with chambered exhaust.


Joined: 1/22/2006
Posts: 1058

I can't think of any cons for going with the 7 blade fan. It will bolt right up and certainly pushes more air than the 5 blade.
Engine Fan (3/13)
 11/22/07 9:35pm
kstyerLifetime Member
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CUYAHOGA FALLS, OH - USA

Vette(s):
1975 C3 Red, T-Tops, Black Interior. All I need is time and money! Getting there!


Joined: 12/2/2003
Posts: 6424

Agreeded.    I would recomment a thermo fan clutch to go with it.
 
A fan clutch will allow a good air flow at low rpm, but turns slower than the engine at high rpm.   It still turns fast enough to move all the air you need, and in fact can move more air than a fan at 5000 rpm due to the air flow turbulance. 
 
In addition, it can cut drag allow for more power at high rpm and better fuel mileage on the highway.
 
All fan clutches do this, but a thermo fan clutch takes it another step.
As the air comes across the radiator, then hits the clutch, it is either hot or cold air, depending on the engine and radiator temp.
 
When the engine is cold, the fan mostly freewheels cutting drag even more.  The warmer it gets, the more air it moves, and the better it cools, as the cooling is needed.
 
If you decide to go with electric fans use two instead of just one.   You need to cover as much radiator space as possible.   An electric only cools the part of the radiator it is directly in front of.   Down the road it will get air across the entire radiator and still cool at high enough road speed.   But at lower speeds you could still have a overheat problem.   
 
With enough coverage by electric fans, you won't have the problem.
 
Even with the mechanical fans, the fan shroud is important.  Again, to maximize the air flow across the entire radiator surface.
Engine Fan (4/13)
 11/23/07 10:40am
bio11
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Oklahoma City, OK - USA

Vette(s):
1972 LS5 Convertible,Auto.Targa Blue with Black Interior.


Joined: 4/1/2007
Posts: 432

When you say thermo, is that the one with the little coil on the front toward the radiator? I'll see if I can find one locally in stock today since today is a work on the vette all day day.
Thanks guy's
Lonnie Green
Engine Fan (5/13)
 11/23/07 11:08pm
rearn2go72
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Bladenboro, NC - USA

Vette(s):
1972 conv., sunfire yellow, blk interior, blk vinyl and convertible top. Off frame restoration with American Speed 383 stroker engine producing 500hp plus a 200hp NOS system. MSD ignition. Hooker super competition headers with chambered exhaust.


Joined: 1/22/2006
Posts: 1058

Thermal fan clutches have a built-in thermostat that detects the air temperature passing through the radiator and air conditioning condenser. The fan clutch engages and provides air flow only when cooling is needed. When disengaged, the fan clutch ‘powers down’ reducing power loss and improving fuel economy.

Here's a pic.
< name="chkRemove_clutch.jpg" value="Remove" =""> http://www.C3VR.com/member_uploads/8301_8400/8356/clutch.jpg
Engine Fan (6/13)
 11/26/07 9:53pm
82delight
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Vette(s):
82 dark red


Joined: 8/9/2005
Posts: 66

I went electric on my 82, and I was having real problems with heat.  I boiled over in the summer, and the coolant temp gauge was too high, and the oil temp gauge was too high.
 
I had my radiator serviced, replaced the water pump with a high-flow (advertised 30% more flow), installed a 160-degree thermostat, tossed the fan shroud, the fan, and the pulley for the air pump (removed thanks to no more emmissions requirement), installed the electric fan kit (dual fans with thermostat for on at 190 and off at 170).  I also installed a on/off switch on the dash so I can manually activate the fans when I run the A/C, and a pilot lamp to let me know when the fans are running, in case I can't hear them at speed.  I installed a bigger alternator, because the fans suck a lot of power.  I put a ball valve in the heater hose so I can shut it off in the summer, increasing the A/C efficiency.
 
The result is phenomenal.  The coolant gauge says that the temp never exceeds 190, even on a hot day in traffic, yet I have heat in the winter thanks the the 160-degree thermostat.  The fans come on at 190, and the temp starts to drop to 170.  If I'm moving during a 75-degree day, they don't come on until I sit at a light.  On days below 65, they don't come on at all.  Another great benefit is that the oil temp is now down, so I scrapped the oil-cooler plans.  I'm sure that the auto trans fluid is like wise benefiting.
 
Knowing the inherent heat rejection problems of a C-3, I would do it all again if I had to.  It's the best mod I've made so far.  Please consider it!  Let us know what you decide.
Engine Fan (7/13)
 12/11/07 11:55am
1969 L46
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Jefferson City, MO - USA

Vette(s):
1969 L46 4 Speed Roadster


Joined: 3/9/2007
Posts: 150

If you are not looking for originality, I highly recommend the electric fans.  I have 4 row aluminum radiators with dual spals and a custom shroud on the Vette and the wife's 69 Camaro.  No overheating problems, ever.  With the Vette, make sure you compliment the install with all of the seals that needed in front of and around the radiator and on top of the radiator support and make sure that you have the chin spoiler for your car.  With the angle of the Vette radiator, air will not flow through it naturally it will look for the path of least resistance.  The spoiler and seals will force the air through the fins and keep the temperature down. 
 
Whatever type fan you use, use the seals!!!   
Engine Fan (8/13)
 12/11/07 4:21pm
DaveMLifetime Member
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Flanders, NJ - USA

Vette(s):
1982 Black, ZZ4, Hooker Side Pipes, 3.55 Rear, Rebuilt & upgraded 700R4, All new suspension, brakes, & new Charcoal interior.


Joined: 1/27/2004
Posts: 2552

[QUOTE=82delight]I went electric on my 82, and I was having real problems with heat.  I boiled over in the summer, and the coolant temp gauge was too high, and the oil temp gauge was too high.
 
I had my radiator serviced, replaced the water pump with a high-flow (advertised 30% more flow), installed a 160-degree thermostat, tossed the fan shroud, the fan, and the pulley for the air pump (removed thanks to no more emmissions requirement), installed the electric fan kit (dual fans with thermostat for on at 190 and off at 170).  I also installed a on/off switch on the dash so I can manually activate the fans when I run the A/C, and a pilot lamp to let me know when the fans are running, in case I can't hear them at speed.  I installed a bigger alternator, because the fans suck a lot of power.  I put a ball valve in the heater hose so I can shut it off in the summer, increasing the A/C efficiency.
 
The result is phenomenal.  The coolant gauge says that the temp never exceeds 190, even on a hot day in traffic, yet I have heat in the winter thanks the the 160-degree thermostat.  The fans come on at 190, and the temp starts to drop to 170.  If I'm moving during a 75-degree day, they don't come on until I sit at a light.  On days below 65, they don't come on at all.  Another great benefit is that the oil temp is now down, so I scrapped the oil-cooler plans.  I'm sure that the auto trans fluid is like wise benefiting.
 
Knowing the inherent heat rejection problems of a C-3, I would do it all again if I had to.  It's the best mod I've made so far.  Please consider it!  Let us know what you decide.
[/QUOTE]
Do you still have the computer in your 82? If you do, does the lower temp. give you any problems with the way it runs? I don't know at what temps. the computer makes adjustments, but the 82 normally runs at about 215 degrees. Running it at say 170 degrees the computer will think it's not warmed up yet. Sorry I don't know more exact info. I was told not to use less than a 190 degree thermostat.
Dave


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Engine Fan (9/13)
 12/11/07 8:26pm
82delight
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Vette(s):
82 dark red


Joined: 8/9/2005
Posts: 66

Hey Dave.  I was a little leery of this, but I didn't expect the extreme cooling results that I got, so I was pleasantly surprised that I actually suffered NO problems from the lower temps.  Maybe my computer is not getting the temp signal correctly.  The engine is actually more peppy, and I get NO spark knock whatsoever.
 
I have replaced the computer in the past due to cease-fire syndrome, but I used the old prom.  Then the second computer failed me one day by losing the idle circuit.  It would only run as long as I kept pumping the gas above idle.  When I got home, I watched the injectors, and they would quit anytime the throttle was at home position.  I put the prom back in the old computer, and it has been running well ever since.  My conclusion is that cease-fire can be cured by reseating the prom, creating a better contact between the pins and the socket.  Just be sure to get all the pins in the socket, and don't bend any.
Engine Fan (10/13)
 12/11/07 8:31pm
82delight
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Vette(s):
82 dark red


Joined: 8/9/2005
Posts: 66

I tried to glue my original seals back in place, but they have shrunken and dried out.  I also have some gaps on either side of the fan, so air can pass through the fins but not the fan kit.  With my hi-flow water pump and my 160-degree thermostat, I seem to be in good shape.  Fans cycle on and off, don't even run below 70 degrees unless I stop for a while.
 
Steve
Engine Fan (11/13)
 12/12/07 1:23am
Adams' AppleLifetime Member
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Duncanville, TX - USA

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#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas


Joined: 11/8/2003
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The ECM won't go into "closed loop" until the coolant temp, AND the oxygen sensors are up and running. Normally, 185 or so on the coolant temp will allow closed loop operation, as long as the O2 sensors are jumpin. If not, it will/may never go into closed loop, which would effect the timing, and fuel injector pulse. Continuous open loop running would mean it is runnning rich, with little advance in the timing. Not exactly the best thing.
The prom can be upgraded to a reprogrammed one fairly easily, and this would allow for the lower coolant temps, basically letting the ECM obtain closed loop status at a lower temp.

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Engine Fan (12/13)
 12/12/07 2:46pm
DaveMLifetime Member
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Flanders, NJ - USA

Vette(s):
1982 Black, ZZ4, Hooker Side Pipes, 3.55 Rear, Rebuilt & upgraded 700R4, All new suspension, brakes, & new Charcoal interior.


Joined: 1/27/2004
Posts: 2552

[QUOTE=Adams' Apple]The ECM won't go into "closed loop" until the coolant temp, AND the oxygen sensors are up and running. Normally, 185 or so on the coolant temp will allow closed loop operation, as long as the O2 sensors are jumpin. If not, it will/may never go into closed loop, which would effect the timing, and fuel injector pulse. Continuous open loop running would mean it is runnning rich, with little advance in the timing. Not exactly the best thing.
The prom can be upgraded to a reprogrammed one fairly easily, and this would allow for the lower coolant temps, basically letting the ECM obtain closed loop status at a lower temp.[/QUOTE]
That's what I was trying to say Approve , Joel to the rescue Clap


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Engine Fan (13/13)
 12/13/07 2:17am
NorskyLifetime Member
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West Burke, VT - USA

Vette(s):
SOLD - "The Toy" - '70 Convertible
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Joined: 1/23/2002
Posts: 7190

I'm looking at a dual electric fan set-up for my F-150.  This particular kit has one fan you set to come on at a lower temp than the second.  It also will kick on the high temp fan when the A/C is switched on.
 
Electric fans will only move air when needed.  A pulley mounted fan will be pushing some air almost all the time.


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