The Stovebolt Site Forums The Parking Lot Big Bolts making a fan shroud

Hello again, now I'm looking at making a fan shroud, which was missing when i purchased the 58 Spartan with a 283. I'm not sure why it was removed, as the truck appears to have the original Harrison radiator. Do any of you have any ideas re how to fabricate one? Also, how close to the fan should it come? The truck, as it stands, does not overheat (boil over), but if the temp gauge is registering correctly, it does stay to the right of center. I would assume that it would be wise to replace the shroud, although to be honest I don't understand the full 'science' of how critical it is....I would appreciate your thoughts on this, as well as the fabrication of one. As always, THANK YOU

A shroud makes all the air the fan moves go through the radiator, instead of some of it bypassing the radiator core and not contributing to the cooling effect. Any good sheet metal or air conditioning shop should be able to fabricate a rectangular box the size of the radiator with a hole in it slightly larger than the diameter of the fan. Bracket it to the radiator mount so there are no big leaks. Important- - - - -don't fully enclose the fan. Half the fan blade depth should be enclosed by the shroud, not the entire fan, so position the shroud so the opening is even with the front of the water pump flange.
Jerry

The shrouds are Model specific, so I would need the exact model of your Spartan to to know which one you need (it could be the same as one used on other the 56-59 models).

Here's what they look like. My 56 8400 has the extension like the one shown, it looks like a 30 gallon barrel cut to length.

Mike B

Jerry, many thanks for the quick reply and the detailed specs. You have helped me understand the importance of the shroud. Mike, the truck is an 80 series....the engine sits back from the rad, so I can see where the barrel extension was probably originally used. I would like to find one 'laying around somewhere', but my instincts tell me what a long shot that would be and to just make one (or have it made up).

Hi Jay, most of the ones you find in the aftermarket are probably going to be made to use with electric fans (like the one I use). But you can make your own. I've seen this done a couple of ways. One guy used a commercial sized cookie sheet (which he cut the edges off of). It fit on his radiator support and then he cut a fan hole and used common galvanized metal to make a tunnel which he had riveted to the cookie sheet. It wasn't what you'd think the factory added. Still I thought it was a clever thought and painted black it wasn't terrible. Another guy had torn apart a gable ventilator (which had close to the right size of the tunnel his fan needed) and had mounted that to something I wasn't able to identify (could have been fiberboard or that stuff used as shower walls). That one worried me, but the tunnel part looked pretty good. Here's the ventilator type I'm talking about: https://tinyurl.com/y99eat2n If he had mounted that on something like the cookie sheet I think he would have been ok. Good luck.

Thanks Jon, Those sound like good ideas and gets me thinking of what I have around here to make one up. I will prioritize 'function' rather than 'form', but will make it look as presentable as possible . If I can't pull it off, I will consider taking some drawings/measurements to a tin shop, as Jerry suggested.

I made my shroud by first cutting a plywood circle about 1/2" bigger than the fan diameter and attaching the circle to the fan mounting surface on the water pump. Then I made a cardboard pattern for the shroud that connected from the plywood circle to the shroud mounting points around the edges of the radiator. Once I was happy with the shape the cardboard became a pattern for cutting the shroud out of aluminum sheet metal. I built the shroud in two pieces, top half and lower half, then screwed them together near the centerline of the fan. This was a bit tedious but worked well for me and I am pleased with the results.

Mark

When doing like Mark did, allow fan blade clearance for when engine mounts sag after a few years.

Ed

I have my fan shroud off and I hope these pictures help. I have a Viking 60 w/a 283 and a Harrison Radiator (it’s having the core replaced) and this is my fan shroud.

Here’s a few more pics

Wow, great pix, thanks Wedgele! Gives me a perfect idea as to what it looked like.....the only difference I can see is that it appears that mine was screwed/bolted to the back of the rad support, rather than the sides. Ed, thanks for the good tip and Mark, thanks for the detailed plans for making one!

I don't know your skill set or what tools you have or have access to but here's one I made for my 52 Willys pickup. It's made out of aluminium, bent on a break, bolted together at the seams (I've welded most but prefer to bolt them now with lock nuts). I used a plasma cutter to cut the holes out. I've made quite a few different shrouds over the years. That shroud obviously uses electric fans. Using a mechanical fan I would have made the hole about 3/4 of an inch bigger than the fan all the way around and bent a piece to give it a lip but if I wanted to keep it simpler I would just make the shroud thicker so the fan would be about half way in and out of the shroud. That is unless there was a big distance it needed to go back then I would make a tunnel or find a 55 gallon drum and cut a ribbed section out and bolt it to said shroud if it were close to the size I needed. Making a shroud for a mechanical fan isn't a very detailed process, the point of the shroud is to be able to allow your fan to let your radiator operate at the best it can by cooling all the edges and corners with maximum air flow.

When using an electric fan, it is useful to slow road air to flow through the radiator when at speed, makeing holes in the shroud that are closed by a flap when the fan comes on allow road air to pass through but close up when the fan comes on to suck all air through the shroud. VW etc. use these.

Thanks!, Pvmt and again, Ed......yes, I have managed to form the basic shroud with the help of an HVAC 'tin man'. An extension tunnel will be required and at the present time I'm looking for something a bit larger than the fan diameter which will work for that...I will make sure that its length is just enough to cover half of the blade....