Fan and Shroud


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Custom Fitting your Fan Shroud
photos and story by Jim Clark, the Hot Rod M.D.
product supplied by Cool Craft www.coolcraft.com

Big engines in early hot rods create unique cooling problems. Grille areas are narrow and the engine bays are small. Increased cooling capacity cannot be attained by making the radiator core bigger so the core has to be made thicker by adding more rows of tubes. This additional coolant capacity and heat transfer area does the job at highway speeds. However, at idle or in stop-and-go traffic not enough air flows across the tubes and fins to keep the engine cool.

To increase airflow at slower speeds a fan is used to draw air through the radiator. A multi-bladed fan attached to the water pump hub, driven by the engine, offers the most efficient means of doing this. A shroud covering the entire core area and funneling the airflow out the rear opening makes this even more efficient.

     In many applications the engine sits too low in the frame and has limited clearance at the front of the engine. This makes the traditional mechanical fan/shroud combo impractical. Electric powered fans offer the best alternative. They are thin and can be located anywhere on the face of the core, though near the top is recommended because in top-to-bottom flow radiators hot coolant is returning there from the engine.

     A shroud makes these much more effective but most of the shrouds have moved the fan back from the core too far. Fan manufacturers have continued to reduce the thickness of the fans and now there is a shroud from Cool Craft that when combined with the fan only measures 2-5/8-inches thick. It’s made up of a 1/2-inch thick formed-aluminum shroud and one or multiple electric thin-line fans. Tabs on the side of the shroud attach to the flanges on the radiator side plates with sheet metal screws.

     My ’32 Ford hi-boy roadster proved to be the perfect application for this unit. The Buick Nailhead sits low in the frame and clearance between the thick radiator core and the water pump make the use of the stock fan impractical. I only have 2-5/8-inches between the core and the shaft on the pump. The 1/2-inch thick shroud clears easily but the 16-inch diameter fan had to be moved to the top of the shroud for clearance. The shroud can be ordered with the hole at any location or supplied without a hole and you can cut it out once you determine where to locate the fan. However, it’s better to supply the simple measurements they need so they can cut the hole and attach the fan mounts.

     The photos and captions show the simple installation and the following information from Cool Craft illustrates what specifications and measurements were needed to complete this installation.

Why not utilize the WHOLE core? Let us make you an aluminum shroud that covers the entire core giving you the maximum temperature drop. Our aluminum shrouds have a standard depth of 1/2" without the fan so they don’t rob you of precious engine space. The shrouds are available with or without a fan. Don't need a fan but need a hole for your supplied fan? No problem. Need the mounting tabs in a special location? No problem. Just supply us with all of the dimensions listed below and we'll take care of the rest.

Custom Shroud w/ 16" Thinline Fan
Manufacturer                            U.S. Radiator
Material                                    Aluminum
Total Thickness wo/Fan(s)        1/2" (No fan(s) included)
Total Thickness w/Fan(s)          2-5/8”
Min. Core Size                           16" x 16.5"
CFM                                         1300

Ordering Information Required:
Height (fin area only): Leave blank if ordering with a radiator.
__21-7/8-inches_______________
Width (fin area only): Leave blank if ordering with a radiator.
__16-5/8-inches_______________
Mounting Tab Locations
__X_ Sides (Downflow Radiators)
____ Top/Bottom (Crossflow Radiators)

Hole Size (1/2" smaller than fan size)
__16-inch fan________________
Hole Location/Fan Location (Usually center, evenly spaced)
__center, at the top________________
Finish
____ Satin (Best for satin finish aluminum radiators)
__X_ Painted Black (Looks great on copper/brass radiators)
____ Polished (Best option for polished aluminum radiators)

Build Requests: Any other information necessary for ordering.

Installing the fan:
When installing electric cooling fans, it is important to cover as much surface area as possible. Mount the fan as high up on the core as possible. Attach the fan to the small area around the core of the radiator where there is a metal lip that is approximately 1/4" to 3/8". This will allow mounting of the fan(s) without compromising the core of the radiator.


	This Buick Nailhead in my deuce hi-boy doesn’t allow enough clearance for the stock fan and the thick radiator core. Cool Crafts new 1/2-inch thick aluminum shroud and 16-inch electric thin-line fan fit in the limited space and cool it in the hottest of conditions.


	Determining where the hole and fan should be placed was calculated by measuring down from the top of the core and core to the closest obstruction. Water pump pulley was closest obstruction as shown in the drawing.


	Size of the custom made shroud varies from one radiator to the next. Width and height of the exposed finned area of the core are taken where indicated to determine those dimensions. Flange on this application where the mounting tabs attach to is 3/8-inches wide


	Custom shroud is available with the exposed side in raw aluminum, painted black or polished.

		Nuts for the fan attachment bolts are welded to the radiator core side of the shroud. Mounting tabs are welded flush with the edge of the shroud.

This 16-inch Spal thin-line fan was the largest that would fit in this application. A smaller fan would not have sufficient capacity at slower speeds and the shroud would block too much of the airflow at highway speeds.

Fan could be mounted directly to the core using tabs that slide into slots around edge of guard. Flanges are used to bolt it to the shroud.


	Fan attaches to the face of the shroud at four points with the screws provided.

Hole in the shroud matches the outside tips of the blades. Mounting nuts are welded to the face of the shroud to ease installation.




		Shroud is positioned on the core and center of the flange is marked on the mounting tabs.


				Hole is drilled in the tab without penetrating the flange underneath.




	A center punch is used to mark the location for drilling



			Sheet metal is slid under the edge of the radiator flange to protect the core when drilling the mounting holes.




		Fan and shroud assembly are 2-5/8-inches thick, the same as the clearance between the core and water pump hub. Fan guard tapers down as it radiates out from the center so sufficient clearance is attained.


	Short self-tapping screws are installed making sure that they are not long enough to damage the core.


	Cool Crafts’ custom aluminum shroud and fan assembly fits in the limited confines providing the necessary cooling where a stock fan could not be utilized. It does that without the bulky look of other similar fiberglass shrouds and at a comparable price.


	For Product Information or technical information for your application visit www.Coolcraft.com or Phone: 602-269-3271 Monday - Friday 8am to 5pm Pacific Time

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