After a 7 year build, my son and I took our new truck on it's maiden voyage. We all know how great that feels. Just a short cruise 'around the block'. On the way back home, 1/2 mile away, the radiator started spewing water. By the time we were back at the shop there wasn't much left. Well, time to re-think the cooling system! My first thought was to check the radiator. We were using the stock radiator from the F6 doner that the flathead came out of. That checked out fine, it was clean. Next I decided to build a shroud for the pusher and built one out of ABS/aluminum. So now I've got a big radiator, all covered up with a shroud, and a little fan in the middle. That wasn't going to work, and DIDN'T. Here's a shot of the fan before I built the (first) shroud:
Are you sure your headgaskets are sealed tight? I had exhaust gasses getting into the cooling passages and boiling the truck over on the first trip or two around the block. May want to re-torque the heads and check timing. Cooling fans are just a band-aid most of the time.
At this point I realized that a pusher was never going to work, but I didn't want to be looking at an electric fan - didn't really like listening to them either. I dug up the stock fan & bracket, bolted it on, and started measuring. Not enough room! We had installed the motor 1 or 2 inches higher than stock, and lowered the radiator substantially. It looked like a 17" fan would clear the radiator inlets if we could get the radiator moved forward a couple of inches. Fortunately the grille was mounted such that it looked possible to move it forward a little. We cut some 1/2" pipe for spacers and managed to move it about 1-1/2" forward. Now I just needed to find the right fan. We needed something with just the right offset and as thin a profile as possible. Contrary to many, I've always had good results with flex fans. Seems logical to me that you need the most fan at idle/low speeds and virtually no fan at cruising speed, which is how a flex fan works. Found a good one at Summit, PN 1817. Seven blades, designed for use with a thick radiator. It arrived 2 days after ordering, looking good. Now - how to attach it to the stock Ford fan hub. After mocking it all up I noticed that the fan was too close to the motor - it interfered slightly with the water pumps. Looked like a 1/2" spacer between the fan and the hub would fix that. As you know, there are 10 small holes spaced around the circumference of the stock hub, used to bolt the fan on. The new fan has the conventional 4 holes. I whittled a piece of 1/2" aluminum into a disk, matching the diameter of the stock hub, then drilled 10 holes around the edge, and drilled/tapped four holes for the new fan. Looks like it gonna work! Here's a shot of the installed fan/spacer:
Good points! I had re-torqued the heads at least once, it was seeping a little from a few studs. Also knew I had a timing issue since I was still using the stock disti.
After a similar experience with my avatar, I knew a fan shroud would help a lot. Hey, why not use the stock shroud. So I dug it out (fortunately I never throw anything away) and proceeded to hack it up to fit the 17" fan. Very tight fit at the top, but I managed to get it done. Looks a little like frankenstein's monster, but it matches the rest of the truck pretty well. Also had to mount the bracket at it's lowest position so I found a belt that was just long enough. It's such a close fit that I need to install the belt with the fan, no way to get it on after. I'm using a narrow belt but will be looking for a stock width.
What carb? Anything but tht stocker and there's no advance at all, that in itself will cause heating. I never had much use for those flex fans. Besides not pulling much air, they are the perfect baloney slicer! Cut through anything that gets in their way.
Success! It takes about 15 minutes to warm up enough to open the thermostats, and then stays at just over 190* all the time. First good cruise was about 90 miles on a ~100* day, never went over 195*. Also installed a Mallory disti since I'm running a 4bbl Holley. This motor runs great! Fires right up and runs cool all day long.
Thanks for the comments, especially 'cool' since this was a father/son project. We started with a '41 2-ton, used the cab, hood, grille, steering, put it all on a '46 one ton chassis (122" EB). The whole 'look' started with my son sectioning a few inches from the center of the '41 commercial (big truck) grille and folding it a little so it would fit between the rails. Here's a shot during construction. The steering arms/tie rod were installed backwards just for rolling around until we got the dropped arms for the 4" dropped axle. The brakes/tires/alt/etc were chosen for COST reasons, have less than $5K in this truck.
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