Best gap between fan & radiator?

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clhyer

clhyer

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Evening folks,
I plan to make a fan shroud, but before I tackle this project I wonder if there is a "best gap" between the fan and the radiator. Presently, I have about 1.75" there. There is a 1" spacer between the water pump and the fan. Could that come out? Is there a need for that spacer? The gap between the fan and the PS belt is just over 2". There has to be enough room for a thermal clutch, but darned if it isn't tight in there already to put this fan on/off.
Thanks,
C
 

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Gap between the fan and radiator isn't what's important. What is important is that the fan blades are at least partially inside the shroud.
 
Yes, my research says the fan should be 1/2 inside the shroud. That means I want my fan in the right spot so I only do it once:cheers: I would like to put the fan clutch on, would it fit in the space I have now?
Thanks,
C
 
1968 is right if you are talking spacing with a shroud, with out a shroud you want it as close as possible with out risking it hitting the radiator.
 
1968FormulaS340 said:
Gap between the fan and radiator isn't what's important. What is important is that the fan blades are at least partially inside the shroud.
Click to expand...
Si.....and that the shroud is sealed up tight to the radiator otherwise the air is going to take the easy path......
 
clhyer said:
Yes, my research says the fan should be 1/2 inside the shroud. That means I want my fan in the right spot so I only do it once:cheers: I would like to put the fan clutch on, would it fit in the space I have now?
Thanks,
C
Click to expand...

Replace the spacer with the fan clutch and see where it's at before you build the shroud.

Fan half in/half out of the shroud is optimum.
 
Take the spacer out and add your thermal clutch, but the fan must be just inside the schroud like mentioned about, it makes like a wind tunnel that way.
 
I suspect that if the fan blades are too close to the rad core, the fan probably won't be very efficient. I certainly would not want it closer than you have now. Additionally, you don't want it so close that a very agressive stop doesn't move the engine enough to whang the fan into the core.
 
The thermal clutch fan is almost the exact same height as your spacer and can be swapped directly in. I did this on my 66, which never would have come with the thermal fan, but I swapped it right and just eliminated the spacer. Heres a pic of my setup with the early A metal shroud. I believe i have just over an inch between my fan and radiator!! geof
 

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HA! I think I got ya beat! Try 3/8" of an inch from my clutch to the radiator!!! It is CLOSE!!! I have the Schumacher poly lock engine mounts, so the engine doesn't move at all. Seems to cool okay, stays at 180 while driving. At a stop light it'll creep to 190.

This weekend I did have an epidemic: I was driving to the ocean to get away from the heat, but little did I know, it was presidents weekend. On the way there was traffic, stop and go, 5-10 MPH tops for 15 miles. Half way into it, I glanced at my mechanical temp gauge, 230 degrees!!!! I immediately pulled over, waited for it to cool down to 180, and continued on home with no problems as traffic picked up.

I think I wanna install a shroud now, like Autoxcuda did in his thread. Don't want that to happen again.



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we used to try and get the fan about an inch from the rad.
..but i think clutch fans turn at about 80% of the pulley speed and may not always be best for cooling at low speed or idle.
flex fans are better...a lot of guys won't use one though.
 
Thanks folks for all the info and pics!
C
 
One danger of "too close" is if you drive in deep water, the fan blades can be pulled forward into the fan. That was on Car Talk.
 
There is a cool DIY fiberglass fan shroud project somewhere out there:
make a center mark on your radiator from the fan, take fan diameter and make a ring from out of something like cardboard 1" larger and exactly the distance from the radiator to the middle of your fan blade width. Eg. Sort of a 18 X 3.5" tall tube. Remove radiator, place wax paper over radiator sides or something that wont stick. Place form on radiator centered on mark and then drape fiberglass cloth over the entire radiator so it looks like a tent. Cut to size and stretch it a little so its taught over the form. Add resin and a few more cloth resin layers. let it set up. Now you can remove it off the radiator (wax paper) and youll have a rigid for fitted shroud. Just cut form out and paint flat black. there you go, a shroud. fan should be 1/2 out of shroud and have 1/2" clearance all around. OR you can make a sheet metal box with a fan circle cut out. It doesnt seal up to the radiator sides well without some sort of AL tape, but looks nice on a rod.
 
The answer is easy as pi!

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Ricenuker, that is the project I was thinking of doing.
Once again, thanks everyone!
C
 
I have started the process/experiment of making my fiberglass fan shroud. Lots of 3 steps forward, 2 steps back... or maybe it's one step forward and 2 steps back.
Anyhow, I have the first coat of resin on it today...
I have taken lots of notes and pics. If I am successful with it I will post the how-to.
One thing I have found out for sure, label everything!!! R-L, "up" and fan side, radiator side. You can see in the pic, not only is the wood scrap labeled R & up, but the cardboard it is on top up is also labeled R and "up".
C
 

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