Projects Help me build a fan shroud

I'm trying to build a fan shroud for my 49 chevy with a 235, stock radiator, and stock fan. I have added an AC unit and mounted the condeser in front of the radiator. I'm going to use the procedure that 4t64rd wrote in This Tech Thread.

I went out today and measured the radiator and the clearances that I have and drew up this diagram.



The stock fan is 16" and I thought I needed about a 1/2" clearance all around. So the Red is the fan, the Yellow is the half inch clearance and the Black is the radiator.

If I measure from the fan to the fins on the radiator the front most part of the fan blade is 1 1/4" and the back is 1 3/4". If I measure to edge of the radiator support, then the fan clearances are 3/4" and 1 1/4".

Here are my questions:

1. How much of the fan should be inside of the shroud and how much outside?

2. Should the bottom be open to allow excess air to escape when speeding down the road? I saw one shroud that had a flexible material on the bottom that allowed the excess air to escape.

3. Is the 1/2" clearance enough?

Any other ideas, tips, tricks, or suggestions are welcome.

Thanks, Bill

 

1. half in and out 2. no 3. yes

 

I'd go 1 inch around if ya could,,rough road or something like that vibration and all it could flex or move,,JMTC


what about an early 60's Impala shroud ?? That might work with some fabbing .

 

The clearance around the fan is subject to how much you engine can move in the chassis. If you have flexible engine mounts you could torque the engine into the shroud and cause a real mess. Also consider a seal around the mounting face so that your fan can and will draw all of it's air through the radiator instead of around it. After adding a 'tight' shroud to my 53 Ford I dropped almost 15 degrees even on the hot days. I have never ran above 185 at anytime now. Shrouds work!!!! I see many cars without them and don't understand why...

 

1. I've always set up a shroud so that 2/3 of the fan blade is inside the shroud and 1/3 outside and never have had a problem.

2. No

3. Yes

 

http://www.jalopyjournal.com/forum/showthread.php?t=380196&highlight=fan+shroud+tech

 

I'm putting a 401 nailhead in a '50 chevy. Ordered an custom built aluminum radiator for it and built my own shroud out of 18 ga aluminum. Here it is. It will have 3/4 inch clearance around the fan and the fan will be 1/2 in and 1/2 out of the opening.