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Electric Fans

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Don's Fan Install

Thermostat Technical Tips

Lincoln Mark VIII Fan

Why a Mark VIII Fan?

For severe cooling needs, the electric fan from the Lincoln Mark VIII provides the greatest airflow.  The part number is F8LH 8C607 AA and is available from Houston Performance for $149.00 plus shipping (as of 09/2002).  This is a brand new Ford Motorcraft part and has a fan diameter of 18" and a uniquely shaped fan blade.   For comparison, the Flex-a-Lite has 16" diameter blades.   Of course blade pitch, shape and speed all contribute to air velocity, but the Mark VIII has a 25% increase in surface area.

NOTE:  The Lincoln Mark VIII fan will draw continuous currents of 33A@12.0V & 42A@14.4V, and has a starting current in excess of 100A!  You will definitely need to upgrade your alternator to a 3G-130A!

Will this Fan Fit?

The dimensions of this fan are 22"W x 18.5"H x 6.25"D.   You can get this fan to fit with your supercharger setup.  Don got his to fit with a 2.5" thick FMS radiator and I've gotten mine to fit with a 2" thick radiator core, ATI ProCharger (driver's side mounting), 7.75" crank pulley, etc.  With a Vortech, it would probably fit with a 3" radiator. The water pump pulley clearance is not really the problem, it's the interference with the supercharger crank pulley.   The key is moving the A/C condenser forward, and the radiator forward and higher. It's all real close, read on to find out how to do it!

How to Make this Fan Fit - Trimming the Shroud

The shroud of the fan needs to be trimmed all the way around for most applications.   The amount is generally 1/2", but could be about 3/4-1" as in my install and Don's case below.  Do not reduce the depth too much or the rotating fan blade will hit the radiator.  Also, reducing the depth will reduce the cooling effect to some degree.   The fan's mounting brackets need to be cut off, as well as one side of the bracket's ribs, if you are able to mount the fan right side up and want to attach the factory overflow container.  The fan and shroud are made of a thermoplastic and trimming with a Dremel Tool is way too difficult.  It generates too much heat and just melts the plastic.  The best way to trim the shroud is with a hack saw blade mounted in a plastic saw blade handle (available at any hardware store or home center), not in a standard hacksaw frame.   Establish your cut line with masking tape and just follow the tape line.  The sharp corners of the ears were ground off with an 4" angle grinder and final finishing was done with a Surform® plane (same as used for shaping Bondo®).

After trimming the shroud, the dimension from the radiator face to the back of the motor is 5.0", however, the the motor is several inches below the water pump pulley.   If you mount it upside down, it will offset to the driver's side because the fan is not centered in the shroud.  If you need more offset, get the SN95 electric fan.

More Trimming

The electrical connector has three spade terminals with the (+) and (-) terminals marked on the connector body; these markings can be difficult to see, so look carefully.   The center terminal is not used.  Rather than attempt to locate the mating connector, standard push-on nylon disconnects can be used; the yellow, 10-13 AWG are the correct size.  I had to grind off the fan connector's mounting tabs because of my tight clearance problem.


Radiator Thickness (Core Thickness) Is Important

Core thickness of the radiator is a factor in determining how much to trim from the Mark VIII shroud.

Core Thickness of Known Radiators


Core Thickness

Factory Stock


Be Cool® Aluminum Universal Fit (#65011)


3-Core Copper/Brass


Be Cool® Aluminum Direct Fit (#60011)


Many other aluminum brands


I was planning to change to a Be Cool® Aluminum Universal Fit (#65011) to allow for the clearance I need.  The factory told me than the core was thinner but after receiving the radiator, I found a number of problems.

The "Bad" 65011 is what Be Cool manufacturers and supplies; the "Proper" 65011 is what they SHOULD BE making.  I talked to Be Cool and the dimensions for the 65011 are incorrect in their own catalog (and therefore in Summit's).   The catalogs specify a 30" width but their engineering drawing show a 28" width.  Since they don't offset the core, it's really not any thinner.  So they are manufacturing them to their drawings, but their drawings are wrong!  Also, overall quality of my unit was very poor.

Be Cool H.O. Mustang 80-93, P/N 65011

  Bad 65011 (the way it IS being made) Proper 65011 (the way it SHOULD be made)
Overall Width 28" 30"
Core Width 21" 24"
Tank Width 3.5" 3.0"
Core to Tank Offset 0" 0.75"
Support Bracket Width 24.5" 25"
Thinner Core Area Effective thickness is same as 3-core due to tank thickness and core to tank offset. No space limitation advantage.  
Manufacturing & Q.C. Overflow brass fitting over tightened & cracked filler neck.  

BeCool 65011.jpg (14087 bytes)

The stock shroud is 23.75"W x 19"H while the Mark VIII fan shroud is 22"W x 18.5"H, therefore, the width of the core must be at least 22".  The Be Cool #65011 has a core width of only 21", enough said!

How to Gain More Clearance

The 3-core copper/brass that I had installed was too thick and the fan hit the supercharger's automatic belt tensioner, which, on my ATI ProCharger is located at about the 2:00 o'clock position of the 8-rib 7.75" crank pulley.  If not for the belt tensioner, it would have fit as in Don's case above.

I solved the clearance problem by moving the A/C condenser forward about 1/2".  I was then able to then move the 3-core radiator farther forward by about 1/2", allowing the top to move the radiator up against the radiator support housing, and by moving it about 1/2" higher by putting thicker rubber pads underneath it.  I put notches in the radiator support housing just like Don did.  All this required bending the support brackets to fit, bending the bracket's locating tab back into it's hole and placing a couple flat washers under the mounting bolt to move them a little higher.  Everything ends up being about 1/2" higher; any more and the support bracket would hit the hood.

I put 2 angle brackets at the bottom of the radiator and screwed them into the frame below to help keep the bottom of the radiator from slipping rearward.   I put 2 angle brackets bent into a "U" at the bottom of the radiator for the shroud to slide into.  I put 2 more angle brackets bent into a "U" at the top of the radiator to clamp the shroud to the radiator.  Look at the photos below and notice these angle-brackets on the top and bottom. The ones on the bottom are permanently attached to the radiator. The ones on the top use the factory shroud mounting clips and screws. There are no mounting holes needed in the fan shroud.  It's a friction fit.  To remove the entire fan assembly is now just like removing the stock shroud, just remove the top screws and brackets and lift the fan assembly out.

I mounted the Lincoln Mark VIII fan right side up.  There would have been more clearance to mount it up side down, except for interference with the superchargers automatic tensioner pulley.  The advantage of mounting right side up is I was able to use the stock coolant overflow container and mount it to the shroud in the same manner as the stock shroud.

Controlling the Fan

Build Your Own

A Bosch 75A relay can be used if you are going to utilize the control system shown below.  Relay can be purchased from Brandon Products Group (1-800-422-3BPG) for $22.62, http://www.bpg-inc.com/.   I would recommend the 0-332-002-156 which has the series and parallel clamping diodes and is specified for motor loads.

NOTE:  The -156 Bosch relay has a polarity requirement on the inputs; 86 is positive, and 85 is negative.


Bosch_Relay.jpg (102783 bytes)


FW_Diode.jpg (67457 bytes)


Since the motor is an inductive load and an inductor is an energy storage device, when the contacts of the relay open, the energy that is stored in the motor has no place to go.  The voltage increases (negatively) and a spark is created across the relay contacts, greatly reducing the contact service life.  If a diode is placed (reverse biased) across the motor, it will not conduct in normal operation but will conduct when the relay contacts are opened, thereby supressing the spark. The current is said to "freewheel" through the diode and the motor after the supply current from the battery is interrupted.  This voltage spike can get unbelievably high, hundreds of volts for a 12V system.  Use a 1N5404 which is rated at 3A, 400PIV.



I made the cover from a plastic paint roller tray, $1.00 at the Dollar Store.  The Bosch relay is the black box on the right (uncovered).

Fan_control_cover_on.JPG (314457 bytes)


Thermostat Housing

M-8592-B302.jpg (9799 bytes) The temperature switch should be mounted in the water outlet connector, also known as the water neck or thermostat housing.  The Ford Racing Performance Parts is the best for the money; it costs less than the stock Ford unit and has a 3/8" NPT hole with plug.  The part number is M-8592-B302 which sells for $21.29, and is available from http://www.oemfordparts.com/


Temperature Switch

TempSwitch.gif (5783 bytes) The 198/189°F (92/87°C) fan (temp) switch (823 959 481 F) is manufactured by Wahler and is used on a 1979-83 VW Rabbit. Use this switch with a 180°F thermostat.  Use the 180°/171° (82/77°C) temperature switch 823 959 481 82 with a 160°F thermostat.  They were previously available from Rocky Mountain Motorworks (now Mid-America  Motorworks).  They are no longer available from that source.  These switches will require drilling out the existing 3/8" NPT hole in the Thermostat Housing with a 3/4" drill bit and threading with a metric M22-1.5 tap.



Lincoln Mark VIII Electric Fan - New out of the box>

MarkVIII_Fan_Front.jpg (14709 bytes)MarkVIII_Fan_Rear.jpg (14062 bytes)

                              Front View                                                           Rear View

Lincoln Mark VIII Electric Fan - Mounted to 3-core copper/brass radiator<

Fan_on_Rad_Front.jpg (19113 bytes)

Fan_on_Rad_Left.jpg (10505 bytes)   Fan_on_Rad_Right.jpg (11033 bytes)

Note mounting brackets to position bottom of radiator forward.   Other mounting brackets hold shroud to radiator, allowing it to be removed while leaving the radiator in the vehicle

New Overflow (from Toyota) with DC Control - Fan Controller

Lincoln Mark VIII Electric Fan - Installed

   FanClearance_1.jpg (77906 bytes)    FanClearance_2.jpg (72825 bytes)

  FanInstalled_2.jpg (117911 bytes)    FanInstalled_3.jpg (113589 bytes)

New Overflow (from Toyota)


I had no problems with cooling while driving down the highway. In traffic or with the A/C on, the temperature would slowly climb, and in the summer, it just kept climbing.   This can take a long time, an hour or more.  It happens fastest after a sustained drive of 20 minutes down the highway followed by sitting in traffic for 10 minutes.  In the winter, with the outside air temperature of 60-70°, the temperature will stay as shown in the diagram on the left.  With the outside air temperature of 80-90°, the temperature will climb as shown in the diagram on the right.

TempGage_180_Norm.jpg (13942 bytes)                                                        TempGage_180_Hi.jpg (13728 bytes)

My situation is more severe than most:

I tried a number of cooling solutions and each helped to some degree:

For those of you without A/C who live in a cooler climate, any electric fan will do the job.

I determined that the problem is insufficient air flow through the radiator.

I made the cutout and it has made a big difference.  I created a 1:1 template in AutoCAD and printed it out on card stock.  Tape the area off with 3M long life tape (the blue stuff), don't use regular masking tape, since it's hard to remove and could pull off the paint. Then tape the template to the bumper cover over the masked area.  Use a sharp awl to punch through the hole centers and into the plastic. Use a 2 1/8" hole saw to cut the curved ends and a jig saw with a fine blade to cut the remainder.  Just cut right through the paper, masking tape and bumper cover with the hole saw and jig saw. Put masking tape on the bottom of the jig saw so as not to scratch the paint and follow the line on the template. Final shaping was done with a sanding wheel on a Dremel Tool. Now remove the remaining template and tape material. The material cuts very much like soft wood and the hole edges were very sharp and clean.

I could have painted the inner edge with touch-up paint but decided to trim it with flexible plastic door edge guard which cost $3.00 for 2-24" strips, comes in mostly black but other colors as well, and has an adhesive built in. It was a little hard to get the edge guard on since the thickness of the ABS nose is 1/8" and the edge guard is for door edges which are about 1/16". Take your time and just work it around the hole. Cut it about 1/4" longer so the two ends fit tight together. Allow sufficient time for the adhesive to set up (a day or two) before washing. It took longer to put the edge guard on than it did to mask and cut. Total install time was about 2 hours.

When finished, it will look like it came from the factory that way and it's a lot cheaper than a Cobra insert.

Cutout.jpg (32661 bytes)

The main advantages of an electric fan are:  (1) faster warmups since the fan doesn't turn on until the thermostat opens, (2) at highway speeds, usually above 45 mph, you don't need any fan at all, so an engine driven fan just wastes power.  For the manufacturer, it means better fuel economy, because they turn the fan off at highway speeds.

The Mark VIII fan works just fine, if you have the room for it; it has a depth at the motor of 6.5" and is right in front of the water pump pulley.   You have to offset it by turning it upside down (since the motor is not in the center of the shroud) or by moving it towards one side of the radiator.  Blower crank pulleys get in the way but if your setup uses the stock serpentine belt to drive the blower, this should not be a problem.

Concerns about cooling in traffic at idle are well founded.   This is the hardest job for any cooling system.  The Mark VIII fan should give you sufficient air flow.  If it can cool a Lincoln, it will cool anything.  The biggest problem with the Mustang is air flow in and out of the engine compartment.   On my GT, I cut holes in the facia (as in the Cobra grille insert).  A raised cowl hood might help even more.  There's just not much room between the fan and the engine and all the hot air must flow through the radiator and fan and down under the engine.

Also, where you live is also an issue.  I have people say that their Black Magic fan works just fine on their supercharged application and then they say they live in Canada!  A 90° day in south Florida is not the same as a 90° day in New York.  The road temperatures (i.e. the surface temperature of the pavement) is a lot higher because of the intensity of the sun and makes cooling at idle in traffic a lot harder in southern climates.

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Revised: June 30, 2005 06:02 PM