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Fabricating A Fan Shroud At Home - Keeping Your CoolFabricating A Fan Shroud At Home From the February, 2009 issue of Rod & Custom By Kev Elliott
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Elsewhere in this issue you can see how the guys at Walden Speed Shop repaired a '32 coupe using a minimum of specialized equipment, most of which a well-equipped home shop will already have, especially if the shop owner already has some sheetmetal fabrication experience, but what if you don't possess a sheetmetal brake or shear? This was the position I found myself in when I needed to fabricate a custom fan shroud for my '46 roadster pickup. Sure, I'm in a fortunate position in that I could go to a number of friends' shops and use their equipment, but I wanted to show that such a project could be tackled at home with no specialized tools and still turn out a decent-looking, finished piece of work. I always knew the radiator in my truck was a little on the small side, and coupled with the fact that it sits so low compared to the motor, an engine-driven fan wouldn't even cover half the radiator core. No fan at all wasn't an option-the radiator boiled over when I returned from a quick blast around the block when I fitted the new Pertronix distributor and coil-leaving an electric fan as one of the few options. Ideally I'd like to run two electric fans, but as you'll see, the steering box on my Caprice front clip sits up against the lower left corner of the core, meaning there wasn't enough space for two, so I sourced a low-profile 12 1/8-inch fan from Flex-a-lite which requires only 2 5/8 inches clearance, mounted it to the radiator, and set out for Bonneville on our recent tour. While the engine ran at 200 degrees throughout the trip, the radiator only got very hot twice in traffic, and both times the air temperature was way over 100 degrees. On my return, however, my first project was to fabricate a shroud in an attempt to lower the running temperature. I knew it would probably only be a temporary fix, as a new, larger radiator is most likely the real answer, but I wanted to see what difference it would make. And did it? Read on... Conclusion
Though the main purpose of this article is to show that it is possible to form sheetmetal and fabricate useful parts for your project using very basic tools, there is another purpose, and that's the experiment to see if the shroud actually works. And it did. And it didn't. Though the shroud keeps the temperature a good 10 degrees cooler in traffic, it actually runs a little hotter on the freeway, most likely owing to the restricted airflow through the core thanks to the shroud! If I'd planned ahead a little more and moved the fan to the right, I'd have had enough room to add a small 8-inch fan from Zirgo on the left side of the shroud, which may have made a difference. Alternatively, I may rob an idea from Spal, whose shrouds have opening vents in them for optimum airflow at speed. I think the answer really though is to fit a larger, or more specifically, thicker, radiator. Or maybe a higher-volume water pump. We'll see, it's an ongoing project. But at least the truck won't overheat in traffic for now, and it's not like there isn't plenty of that in Southern California!  I have no idea what my radiator...  I have no idea what my radiator came out of but it features slotted holes top and bottom. Once I installed the supplied brackets to the fan and placed it on the radiator, they reached the four holes in the radiator perfectly. Here's the fan mounted and wired, and this picture gives a good indication of just how much of the core isn't covered by the fan. However, it did its job in extreme temperatures for over 2,000 miles, and I was impressed with its performance, but once back from Bonneville, I wanted to fabricate the shroud.  With 2 inches between the...  With 2 inches between the fan and the water pump pulley, I figured a 1 1/2-inch deep shroud would be perfect, still keeping the fan relatively close to the radiator yet allowing enough space to pull air through the core.  This picture was taken on...  This picture was taken on my return from Utah, and you can see the remnants of the minor overheating issues splattered over everything. Moreover, you can also see how the steering box location would interfere with fitment of the larger Flex-a-lite shroud, covering the lower corner of the radiator and necessitating a one-off item.  My core measures 26 1/4x17...  My core measures 26 1/4x17 inches, so knowing I wanted the shroud 1 1/2 inches deep I made a pattern from paper allowing me to make the shroud from one piece of steel and transferred that to a sheet of steel.  This handy tool from Miller...  This handy tool from Miller shows the steel is 16-gauge, perhaps a little thicker than required but my local steel supplier will only sell 8x4-foot sheets and the metal recycling yard had this piece for $10. 16-gauge it is then!  Even good-quality tin snips...  Even good-quality tin snips won't appreciate cutting 16-gauge, so I used a 4-inch grinder with a cutoff wheel, as well as an air nibbler and cutoff saw.  The nibbler saves time and...  The nibbler saves time and gives a cleaner cut, but this whole project could be done with the electric grinder. I used the nibbler on the long straight sections while the grinder was used to cut into the corners.  On the rounded corner to clear...  On the rounded corner to clear the steering box, I used a rotary air file to make the curve, but a hand file would work just as well. The dotted lines are where the steel will be bent, just like forming a box.  As mentioned in the text,...  As mentioned in the text, I don't possess a sheetmetal brake, but I do have an old Black and Decker Workmate bench, a selection of C-clamps, and various lengths of scrap steel. Using a length of 2x2x1/4-inch angle above and 1x1x1/8-inch angle below, all clamped to the bench, I used a club hammer and a length of 1/2-inch-thick steel to 'fold' the lower side of the shroud to 90 degrees.  Once folded and while still...  Once folded and while still clamped, I used a body hammer along the fold to ensure it was uniform along its length. This is the first of two bends, as you can see there's another dotted line where the return lip will be bent to allow the shroud to mount to the slotted holes in the radiator.  This time the 2-inch angle...  This time the 2-inch angle was too wide to be used on top (the 1/4-inch thickness is ideal to keep the top surface from warping during the bending process) so I used it underneath, with a length of thick wall box section above. Three clamps keep it secure, and the sharp edge of the angle iron translated into a nice sharp bend in the steel.  Here are the two bends on...  Here are the two bends on the bottom of the shroud. These steps were then repeated for the top.  If this were folded in a box...  If this were folded in a box and pan brake, some of the finger sections would have to be removed to fit the steel into the brake. I achieved the same result by cutting a length of 2-inch box section to fit between the folded edges.  With the box section 'inside'...  With the box section 'inside' the shroud and the heavy angle above, it was all clamped to the bench before I used a length of 1/8-inch plate to force the steel downwards to form the angled edge of the shroud. A second bend was then formed as shown previously to complete the 'box.' The same technique was used to form an angle on the other side of the shroud, albeit a longer section. These angles are an attempt at creating airflow to the fan, rather than just have the shroud as a square box.  With the small sections that...  With the small sections that will form the recess for the steering box bent, the only additional steel required to complete the curve was formed by bending it round a piece of exhaust tubing and welded in place.  Here's the larger angled section...  Here's the larger angled section having its edge welded. Note the weld on the right has already been ground back.  With the welding complete...  With the welding complete the excess has yet to be trimmed from the edges, as denoted by the Sharpie line. The sides of the shroud were trimmed 3/16 inch farther back than the top and bottom mounting flanges, as they will have rubber edging fitted to protect the core from the steel edges.  With all folding and welding...  With all folding and welding complete, the hole for the fan was cut. Leaving this until last prevents the shroud from warpage during the bending process. Bolts were also welded to the shroud at this stage to mount the fan.  Mounted in the car (not an...  Mounted in the car (not an easy job and I nearly resorted to cutting it in half and bolting it back together once fitted just to get it in!) you can see how it covers the entire radiator core except for the section where it is recessed to clear the steering box.
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