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Old 11-22-2008, 01:43 PM
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Radiator to shroud clearance??

In my '46 Chevy Panel I've got a 350 sbc and a 4 core alminum radiator with a 2750 cfm 17" electric fan. It is mounted by three brackets that I made but I want to put an alminum shroud around it. With the brackets the fan is mounted almost tight to the radiator and I need to pull it back alittle when I mount it to the shroud to get better air flow. As close as I can figure I can only move the fan back 1/2" from the radiator any more and I get to close to the water pump pulley. Will this be enough clearance to get the full air flow effect of the shroud?

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Old 11-22-2008, 02:44 PM
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A properly designed shroud is one that lets all of the air that goes through the radiator go through the fan .....just think of the shroud as a funnel.... taking all the air that goes through the radiator core and funneling it to the fan. To work properly the fan needs to be in the rear opening of the shroud.
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Old 11-25-2008, 08:03 AM
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Here is what I made up. Had a sheetmetal shop bend the aluminum box($37), cut a hole for my fan and mounted it to the radiator. I do not have the car together to see how it will work. I was told if it runs warm going down the road I might have to drill a few vent holes in the shroud to help air flow.

[IMG][/IMG]

[IMG][/IMG]
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Old 11-26-2008, 07:46 AM
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47 Chevy, Thats exactly what I'm planning on doing thanks, How much clearance do you have from the core to the shroud? My fan is mounted high center and I'm concerned about drawing the air up from the bottom portion of the rad.
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Old 11-26-2008, 08:11 AM
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[IMG][/IMG]



My fan is mounted in the center of the shroud, that is where it fit the best. The shroud is about 1 inch from the core. I did have to mount the fan on the frontside of the shroud to have clearance on the waterpump, that did reduce the fan to radiator clearance by about 3/8". I will try to get better picture today.

Last edited by 47chevy; 11-26-2008 at 12:05 PM.
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Old 11-26-2008, 05:10 PM
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it should be fine at 1/2 inch from the radiator.
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Old 11-27-2008, 12:20 PM
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JMO IME
The face of the shroud needs to be as far from the radiator core as reasonably possible, even if that means offsetting the fan to one side or toward one corner to avoid the pump shaft for additional clearance. Two smaller fans side by side usually move more air and eliminate the shaft clearance problem.
A distance of 1 1/2 inches should be considered minimum for unrestricted airflow, as well as a "funnel design" if possible which enhances airflow at speed.

Above 30 mph no fan should be required, so if overheating occurs as road speed, then relief holes that automatically close with rubber flappers might be necessary to get enough airflow through the radiator.

For superior cooling a high pitch mechanical fan is much preferred,
especially with a thermostatic fan clutch.
4 inches of clearance is needed to get a fan clutch in there, depending on the applicaton. Looking at those pictures, I would use a thermostatic fan clutch.

An electric fan with 2700 cfm free flow will NOT cool a decent 350 engine unless you have a humongous radiator and a high flow water pump.
Air Conditioning will probably be out of the question.
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Old 11-28-2008, 10:22 AM
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Here are some of the issues that I was facing on my project. Yes I tried to use the original fan, moving the engine up or down was also explored. I think the mechanical fans cool better but there is sometimes that its is almost impossible to use them. I could have used the factory intake tube, which would of solved the fan hitting it but then it was in the way of the radiator hoses and was too long.


Here is the mechanical fan with the original radiator. The blades hit the lower outlet and the intake tube.

[IMG][/IMG]

[IMG][/IMG]

Here is the brace, with this setup I do have barely enough room for everything. I hope this will work, if not back to the drawing board.

[IMG][/IMG]




Quote:
Originally Posted by ScoTFrenzel
JMO IME
The face of the shroud needs to be as far from the radiator core as reasonably possible, even if that means offsetting the fan to one side or toward one corner to avoid the pump shaft for additional clearance. Two smaller fans side by side usually move more air and eliminate the shaft clearance problem.
A distance of 1 1/2 inches should be considered minimum for unrestricted airflow, as well as a "funnel design" if possible which enhances airflow at speed.

Above 30 mph no fan should be required, so if overheating occurs as road speed, then relief holes that automatically close with rubber flappers might be necessary to get enough airflow through the radiator.

For superior cooling a high pitch mechanical fan is much preferred,
especially with a thermostatic fan clutch.
4 inches of clearance is needed to get a fan clutch in there, depending on the applicaton. Looking at those pictures, I would use a thermostatic fan clutch.

An electric fan with 2700 cfm free flow will NOT cool a decent 350 engine unless you have a humongous radiator and a high flow water pump.
Air Conditioning will probably be out of the question.
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Old 11-28-2008, 06:16 PM
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challenges!!!!!

Nice cold air intake. Most people just stick the Mass Air and filter straight out the front.

Moving the lower radiator outlet might be a possibility.

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Old 11-29-2008, 09:46 AM
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Quote:
Originally Posted by ScoTFrenzel
challenges!!!!!

Nice cold air intake. Most people just stick the Mass Air and filter straight out the front.

Moving the lower radiator outlet might be a possibility.

Had no room for a front exit air filter, moving the radiator outlet was done. It still did not have enough room. The radiator is a PRC unit. I know that there are several that have installed the ls style engines in old cars and something better has to be out there.
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Old 12-02-2008, 01:11 PM
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OK 47 now we are getting to strange, the radiator in mine is a PRC also. It has been cooling mine great for two years now I just want a better look around the fan and radiator.
This is what I came up with for my final mesurements today. The shroud will be 1 1/4" from the core and with the fan mounted on the inside like yours it will be minus 3/8" so the fan will be 7/8" from the core. And I will have to remove a couple of unused mounts from the fan for a cleaner look. It will be a little while before I get it all done but I will let you know how it comes out.

David
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Old 12-02-2008, 01:32 PM
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Looks like you have some room between the radiator and grille, so what's the problem with making some "Z" brackets and moving the radiator forward?
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Old 12-03-2008, 08:15 PM
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Quote:
Originally Posted by techinspector1
Looks like you have some room between the radiator and grille, so what's the problem with making some "Z" brackets and moving the radiator forward?
That is exactly what I did on my Plymouth to get this in.
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