Adding a Fan Shroud

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rod7515

rod7515

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Im working on my 66 Dart with a 408. Still trying to get a better driving temp to keep car cool in all conditions so Im adding a shroud around the mechanical 15" steel fan I am now using. The shroud I bought is 2.5" deep. I will need to make some mounting brackets on the sides since it came with mounting on the top and bottom which is not going to work on the radiator I am using. My questions in trying to use this are as follows, how far shoulr the fan be inside the shroud vs outside the shroud. The fan looks like it is going to be about 2" or so inside the fan shroud while the back of the fan will have about .5 - .75" of fan outside the shroud. Im not going to be able to put the round circle part of the shroud around the fan because it would cover all of the fan. Lastly since I almost forgot to put this in post, how much clearance would you leave for the fan blades to clear the shroud. I was thinking the circle I cut in the shroud should be about 17" round which would give me a 1" clearance all around. The shroud is only 17.5" high so i wont have much shroud left on top and bottom.
Here are some pics showing what I am working with and hopefully it makes some sense to what I am trying to explain.
Let me know what knowledge your experiences have given you when working with these types of problems. And what do you think I should do. Is my plan a good one or will I need change my thought pattern to make it work?
Thanks Rod
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Your shroud built as you describe it should work fine. I built my own shroud for my 67 Barracuda and it fits about as you describe with my clutch fan. My car runs at the thermostat temp of 190 and I can watch the stat open and close on my mechanical temp gauge.
 
DesertRat
Did you have heating issues before you made your shroud or did you build a shroud right away and dont know how it ran without it? If it was after you had cooling issues how much difference in temps did the shroud make? Does your temps fluctuate when your in traffic now with the shroud on?
What engine are you running and has it been bored or modified?
Thanks Rod
 
Glad to see you're building your shroud with some depth to it. Too many people put a flat piece of aluminum maybe 1/2" from the radiator with a hole in it, & wonder why they are still having cooling problems.
I cant answer about the depth of the blades in the hole, but I think you should be fine. You do want some of the blade out, my guess is to "fling" the hot air outward instead of piling all up at the block, water pump, Alt., & A/C & P.S. if so equipped.
 
rod7515 said:
Im working on my 66 Dart with a 408. Still trying to get a better driving temp to keep car cool in all conditions so Im adding a shroud around the mechanical 15" steel fan I am now using. The shroud I bought is 2.5" deep. I will need to make some mounting brackets on the sides since it came with mounting on the top and bottom which is not going to work on the radiator I am using. My questions in trying to use this are as follows, how far shoulr the fan be inside the shroud vs outside the shroud. The fan looks like it is going to be about 2" or so inside the fan shroud while the back of the fan will have about .5 - .75" of fan outside the shroud. Im not going to be able to put the round circle part of the shroud around the fan because it would cover all of the fan. Lastly since I almost forgot to put this in post, how much clearance would you leave for the fan blades to clear the shroud. I was thinking the circle I cut in the shroud should be about 17" round which would give me a 1" clearance all around. The shroud is only 17.5" high so i wont have much shroud left on top and bottom.
Here are some pics showing what I am working with and hopefully it makes some sense to what I am trying to explain.
Let me know what knowledge your experiences have given you when working with these types of problems. And what do you think I should do. Is my plan a good one or will I need change my thought pattern to make it work?
Thanks Rod
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Is that a summit shroud / Looks a lot like mine, I split mine in the middle on the sides to make it unbolt in the middle. Got my 17'' fan about 1/2 in and half out 'maybe a little more in". 28x19 / 1 1/4 tube griffin crossflow.
If u tie ur engine down u could run w/ tighter clearance, mine is on a motor plate, w/ about 3/8-1/2" clearance at the most.
I could do a little more trimming and run a 17 3/4" fan , but the pass. side would be in the edge of the shroud.
Not needed yet , seem to have the cooling under control . I have a 14" booster fan in front , but it doesn`t come on set at 200.
I have a bunch of fans , a couple of clutches/one is a new jaguar short that is only 2 5/8" tall, a reg 3' clutch , a 14" elec. fan ,
if u need anything let me know , I may have it , and need to get rid of all of it . . Most of the stuff is new, or near new, I tried a lot of things top keep the 440/505 cool in Okla. weather , in the small engine bay----------
 
15" fan seems a little dinky sized IMHO. The performance small blocks of late 60s used an 18" fan, typically with a clutch. I used an 18" fan setup with a 1990 shaguar XJ6 clutch Hayden 2675. Since the diameter is bigger than sections of the radiator I had to make my own shroud. I used a homemade wooden buck, and an old cotton T shirt as a basis for it, then fiberglassed it, bracketed it.

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Famous Bob, yes it is a summit fan shroud. Looks like it should work ok,
Moparmat2000, it's obvious you have much more talent then I have!! That's a superb looking shroud! Is there a tread you did to instruct us on how to do it?
As for the 15" fan, it covers all of the up and down core and 80% often across core. The radiator core is only 17"x20".
Would like to know more about your fan shroud and how you made it !!!
Thanks Rod
 
moparmat2000 said:
15" fan seems a little dinky sized IMHO. The performance small blocks of late 60s used an 18" fan, typically with a clutch. I used an 18" fan setup with a 1990 jaguar XJ6 clutch Hayden 2675. Since the diameter is bigger than sections of the radiator I had to make my own shroud. I used a homemade wooden buck, and an old cotton T shirt as a basis for it, then fiberglassed it, bracketed it.

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That should cool!
 
FamousBob
I forgot to say I do have motor tied down with a solid tie down. I forget who I bought it from but it shouldnt go anywhere!
Rod
 
rod7515 said:
DesertRat
Did you have heating issues before you made your shroud or did you build a shroud right away and dont know how it ran without it? If it was after you had cooling issues how much difference in temps did the shroud make? Does your temps fluctuate when your in traffic now with the shroud on?
What engine are you running and has it been bored or modified?
Thanks Rod
Click to expand...
My build is a 273 out .040 with a Commando++ type build. I had the stock radiator recored to a 4 row X 7/16" configuration but during my cam break-in and watching the temperature gauge I knew right away I needed a fan shroud. I just measured everything up and fabricated my own using some of the advice on the issue found here on the forums. I did change from the stock 4 blade fan to a five blade clutch fan to help things out. For me the keys were standing the shroud box off the radiator at least 2" and giving the fan/shroud clearance the proper distance. I had no plans so I knocked out a drawing on CAD and went from there. The result keeps my car motor nice and cool in any ambient temperature. I could help it more by separating the transmission cooling from the radiator but it was not necessary in my case. Below are a couple photos.
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I had a thread on fabo that I put it in. After making the wooden buck, just stretch cotton fabric over the mold and staple it to the back. Then layer it up with about 4 coats of fiberglass resin. Letting dry and scuffing between each coat. When dry, pop it from the mould. You notice the mould has plastic on it to prevent the cotton fabric from sticking to it. Once you pop it out, flip it over and screw it down to a piece of plywood with screws thru the circular center part, now fiberglass the **** out of it on the inside. I used about 3 layers of 7781 thick weave fiberglass. Once that's dry, unscrew it from the plywood, and cut it out. You can then figure out a mounting system. I made pieces of 19ga steel sheet with fingers. I glued it in place w jb weld then drilled and installed countersink rivets in the tabs to also hold it, then bondoed over the heads to hide them. Where the hoses had to fit with u shaped cutouts, I filled those spots with JB weld, then ground out the u shaped notches.

The big key is making the wooden buck accurately so the fan is centered. The center circle I have measured 19.5" for an 18" fan. This gives me .75" clearance all around for engine movement. Fan is half inside the shroud to allow scavenging. The other piece to the buck I made in the shape of the radiator rectangle, taped a pen to the fan blade and rotated it. This gave me location of the circle for the fan. This was transferred to masonite board. I figured out the height and used 2x4 blocks to space out the round disc. Used all thread and nuts to assure the disc was centered until I screwed it down to the wooden blocks. You can see I used an old black pocket T shirt stretched over then wired and stapled to the back of the wooden buck to get the shape before putting fiberglass resin on it.

I am using same setup in my sons car, and will make another shroud, and mounting rails. I kept the buck and templates.

Pix of the buck.

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The small problem I see is that you have to use a solid bolt-on, direct drive to fit your fan with that aftermarket aluminum radiator.

Looks like there's no clearance for even the short Jaguar Thermal clutch fan. A buddy of mine had the same problem in his B-Body with 22 inch radiator. He convinced the manufacturer to offer the shorter Jaguar pump for Mopars, although even with that, he didn't have room. Eventually, he ordered a 26" stock brass configuration radiator, which also moved the core face forward of the fan back to the stock dimension of clearance. He then opened up his radiator opening to allow the wider radiator to fit the car, and it allowed enough room for the thermal clutch.

I built a steel shroud so that the fan is half way out of the circular portion of the shroud and allowed 1/2" to 3/4" clearance with the opening. It's works very well. I do have enough room to run the factory Magnum thermal clutch and 5 blade fan. They did make a fan with even more blades, but that makes the car sound like an airplane is about to take off.
 
I've got the shroud cut to fit the fan and I split it in half to make a top and bottom. Made brackets to tie it all back together and now I'll need to figure out I'm going to mount it to the radiator. I have a pulley kit coming next week to overdrive the water pump faster and hoping the lower pulley will clear the fan since the serpentine kit did not. With these 2 changes I'm hoping my overheating issue will be gone. I'll let you know how this turns out. Heres a few pics of shroud and how it should fit in car.
Rod
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Is your radiator from Engineered Cooling products? If so it will have radiator shroud mounting side flanges. You can make mounting tabs on your shroud out of the aluminum you cut out of the center of the shroud kit for your fan hole.

Fab em up, and pop rivet them in place, use body clip nuts on the flanges and regular SEMs body bolts. I have found with pop riveting brackets if you scuff the metal good at the bond joint, and use a bit of jb weld between the pieces then wet install everything the brackets shouldn't rattle loose over time from vibration. Use enough rivets and spacing when you make up the tabs. It's better to make the tabs bigger and have more surface area for the rivets and for the pieces to mate together. I'd make the tabs with 5 rivets each with staggered spacing.

I used 14-20 steel riv nuts or nut serts in the radiator flanges on mine, and used sems body bolts w the captured washers.

Hope this helps
Matt
 
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Matt, yes my radiator is an engineer cooling product. The problem I'm going to have is that the mounting that was on the radiator is just slightly inside the shroud now and I dont want to narrow the shroud. I'm just going to add some type of bracketry as you said using the aluminum I cut out from center. Just haven't decided how to go about it yet. Here are some additional pics that would not upload with my previous post.
Rod
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I know exactly what your dealing with, as I have the same type of radiator an ECP for 74 A body. Something like this. The aluminum brackets would work. Making them out of steel sheetmetal would be even better from a vibration cracking standpoint. 19ga steel sheet should be fine. If you do make them from the same aluminum as the shroud, make sure your bend is against the grain of the aluminum, NOT with the grain of the aluminum. If you bend them with the grain of the aluminum they will be weaker, and will crack and fail in short order. This is how I would make them and stagger pattern the rivets. If going this route use steel pop rivets not aluminum. 1/8" diameter ones should work if JB weld bonding everything. I play w aircraft aluminum structures for a living. Vibration causes lots of failure points in aluminum. Tuck the brackets inside the shroud like my pic shows so all you see is the staggered rivet pattern. If you make a template out of metal with your pattern you can duplicate it in 4 locations on the shroud to make it identical. Many smaller fasteners will have more strength than 1 or 2 larger ones in this application.

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Your rad flanges may already have holes in them, use auto body clip nuts, make your brackets to line up with those.
 
I finally got the shroud mounted up and it fits great to the radiator. I dont have any pics yet but will post some on Monday night once I get back home. Its totally sealed with black foam that you would use to mount a camper top to the rear of your truck.
A few questions about theory for cooling.
First during my search and experiments to make my car run cooler I started with a 195* thermostat, then to a 180* then a 160*, then tried no thermostat and with each test once it was on the road would range up to about 200* or less and in traffic it would go up to 220* plus and very quickly I might add. All of these tests were done at between 75*-80* outside temps.
After I installed the 15" 5 blade fan and shroud and I test drove the car Friday afternoon when temps were just about 94* outside and the car ran at 185*-190* while driving on the open road. Once I would stop in traffic it would go to about 210* but when I started moving again would drop back to 185* or 190*. And it wouldnt go up as fast or as high as in previous tests. I have the 160* thermostat in the car now however I am going to change it back to a 195* on Monday and try it again.
Im thinking that with the 160* once the thermostat opens it stays open and the coolant doesnt stay in the radiator long enough to cool therefore the coolant temp continues to go up while the thermostat stays open. Im hoping that the 195* stat will allow the coolant time to cool in the radiator before the thermostat will open and close.
Am I off base on this theory?
Also my fan is all but inside the shroud, maybe a 1/4" is outside. I have no room to bring it back because I am not using a spacer at all. The only way I could get the fan to be partially out would be to cut the shroud down which would mean the shroud that is now about 2.5" deep off radiator would be 2" or less deep. It would also be a ***** to cut it down. How Important is it to have the fan outside the shroud? I can remember many cars in my younger days (mostly GM's) that the fan would be totally inside the shroud but the shroud would be 4-6 deep. Some Monte Carlos would have a long tunnel as part of the shroud. I remember having to replace water pumps on them when I turned wrenches for dad in the late 70's and 80's.
I would like to have another 10*-15* more drop in my running temp. Maybe a 180* thermostat.
I think Im on the right track!
Looking forward to your thoughts.
Rod
 
I bought a shroud off a dodge truck at pick n pull for $5. It adapted pretty easy to my 69 Barracuda. It’s not perfect, but looks & works pretty good.
 
rod7515 said:
Im thinking that with the 160* once the thermostat opens it stays open and the coolant doesnt stay in the radiator long enough to cool therefore the coolant temp continues to go up while the thermostat stays open. Im hoping that the 195* stat will allow the coolant time to cool in the radiator before the thermostat will open and close. Am I off base on this theory?
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two things, the thermostat is to keep the engine at a minimum temp, not cool it off. you want to run the liquid though the radiator faster rather than slower. yes the stuff in the radiator cools more if it's in there longer, but the stuff in the motor is getting hotter at the same time. a crappy thermostat is already a restriction. since your going back in anyway, get a stewart
 
rod7515 said:
I finally got the shroud mounted up and it fits great to the radiator. I dont have any pics yet but will post some on Monday night once I get back home. Its totally sealed with black foam that you would use to mount a camper top to the rear of your truck.
A few questions about theory for cooling.
First during my search and experiments to make my car run cooler I started with a 195* thermostat, then to a 180* then a 160*, then tried no thermostat and with each test once it was on the road would range up to about 200* or less and in traffic it would go up to 220* plus and very quickly I might add. All of these tests were done at between 75*-80* outside temps.
After I installed the 15" 5 blade fan and shroud and I test drove the car Friday afternoon when temps were just about 94* outside and the car ran at 185*-190* while driving on the open road. Once I would stop in traffic it would go to about 210* but when I started moving again would drop back to 185* or 190*. And it wouldnt go up as fast or as high as in previous tests. I have the 160* thermostat in the car now however I am going to change it back to a 195* on Monday and try it again.
Im thinking that with the 160* once the thermostat opens it stays open and the coolant doesnt stay in the radiator long enough to cool therefore the coolant temp continues to go up while the thermostat stays open. Im hoping that the 195* stat will allow the coolant time to cool in the radiator before the thermostat will open and close.
Am I off base on this theory?
Also my fan is all but inside the shroud, maybe a 1/4" is outside. I have no room to bring it back because I am not using a spacer at all. The only way I could get the fan to be partially out would be to cut the shroud down which would mean the shroud that is now about 2.5" deep off radiator would be 2" or less deep. It would also be a ***** to cut it down. How Important is it to have the fan outside the shroud? I can remember many cars in my younger days (mostly GM's) that the fan would be totally inside the shroud but the shroud would be 4-6 deep. Some Monte Carlos would have a long tunnel as part of the shroud. I remember having to replace water pumps on them when I turned wrenches for dad in the late 70's and 80's.
I would like to have another 10*-15* more drop in my running temp. Maybe a 180* thermostat.
I think Im on the right track!
Looking forward to your thoughts.
Rod
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I believe your theory is correct. I’m running a 190 degree stat. I drilled a 3/16” bleed hole in it. My car runs at 185-195 at cruise and 190-200 in town in 85/90 degree summer weather. Parked and off it climbs to 210 and as soon as it starts drops to 190. I also use a 7# cap and an overflow capture/reuse tank.
 
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