Hot Rods Fan Shrouds

I think I need to fabricate a fan shroud for my flathead powered car.
It doesn't overheat, but gets hot when Idling in slow traffic.
I have a mechanical fan, but it is farther away from the radiator core
than I would like, but because of the 4 core radiator, the other fan that
I have won't fit.
This is on a 32 Ford. I have a 39 fan on it currently and it's a bit far from
the core- about 4"s. The other fan that I have is 32 fan but it's too long, so
a shroud is now in order.
I'd like to know the proper way to construct one so that it's the right depth,
etc.
Thought I'd add: the radiator clean, block is clean, 50/50 antifreeze, 170 degree
thermostats, 10# cap.
Only gets hot, not boiling, in slow traffic when the outside temperature is
above 95 degrees (real often in Norcal). Gauges get to 225 degrees, would
like it less.
Thanks for any assistance
Jim

 

Jimmy, you know they are going to ask for pics!

 

Many factory shrouds are good to take "Qs" off of,they are basicly a box coving the rad. core back with hole that lines up with the fan,with a flair around the fan blade. I like that type best,as it can suck air flow across all the core,not just at the flair around the fan only
.
The fan blade with the right flair around the blade=only 1/2in. off the blade tips,can really help,plus it can as far back off rad as needed,as long as the flair dose not end before it;s pass the blade to rear.

 

That is the way I made mine. First a cardboard mockup, then the box fabed out of alum. The flare around the blade is a chromed piece from Speedway. See photo's, hope this helps. My 32 runs cool with this setup.

 

See my post.

 

10# cap seems a little much.Most only need 4#.

 

Teriminate your shroud at the center line of your fan, that is 1/2 of your fan should be exposed, for maximum efficiency. Also cover the whole radiator core on the other end. This is difficult going from round to rectangle, but that’s the only way to do it right. Sometimes you can modify an old shroud to fit easier than starting from scratch.

Bones

 

I held a piece of soapstone against the tip of the fan blade to draw a circle on my rad core to get a sense of how the shroud should look like

Sent from my SM-T350 using The H.A.M.B. mobile app

 

What radiator are you using. If it’s an original, a 4 lb max pressure is about max before you start popping solder joints.
Original style pumps?
Do you have an overflow tube on the radiator positioned low on the fill neck below the cap?
What’s hot? At a 95 degree air temp they will normally run up to 200-205 during idle. That’s still at operating temps.

 

I like to make them with a top, bottom, sides, and a ring for the fan. I use 1/16th" welding rods to mock them up, works well for me.

 

There have been a few fan shroud construction posts on the HAMB over the years. Two that I recall:

1. The guy used a galvanized garbage can that was the correct diameter for his fan, cut it down to the length he wanted, and fabbed mounting brackets. It had a nice rolled edge, downside is that it only drew air through the portion of the radiator that the diameter of the shroud spanned.

2. Another guy made a hoop of steel rod the correct diameter for his fan, held it in place with some wood wedges between the fan blades and the loop, stretched t-shirt material from the loop to the edges of the radiator, and then hit it with fiberglass resin. After it set up he removed it from the car and laid additional fiberglass matting over the t-shirtshroud to reinforce it.

 

Cookie sheets can start as a base. Some have 3/4" edges and a rectangle. Something to think about.

 

This one is on a radiator for a 1-1/2 ton Chev truck I have out here and someone hacked the tar out of it before I got it, in the take a torch to it rather than unbolt something line of thinking but it might give some ideas as it is about as simple as they get .

 

Here is what I did. First I tried a 15” fan then built a shroud using a 16” cake pan and made it in 2 pieces to make it easier to install and remove. Ride ran hot. Then swapped 6” pump pulley for a 5” and added spacer and a 17” fan I had laying around. It never got above 190-195 at a idle. It moves a lot more air even without a shroud. So now I’m fabricating another that will be 2 pieces to ease in simple maintenance instead of 1 piece.

 

I've seen a couple with just a ring like that around the fan and the rest of the radiator open around it. I'd think it would cut down on turbulence off the ends of the fan blades helping all of the air flow back from the fan.

 

Billm on the HAMB hammer formed one out of 22 gauge steel. He has an article on his website. http://myplace.frontier.com/~wgmumaw/shroud/shroud.htm

Dave

 

I want to thank all of you for your responses & suggestions.
Gives me lots of ideas & a lot to think about.
Thanks again
Jim

 

I used one of these: https://www.speedwaymotors.com/Walker-WS55A-Radiator-Fan-Shroud-Style-D-22-x-18-Inch,34435.html

 

Built by Ron Gagnon, from a commercial baking pan I gave him. It's now painted black.