2nd gen electric fan swap

Hi, I'm planning on tossing my belt-driven fan in my 1970 Trans Am and instead going with 2 electric fans. The radiator is 17" x 27.5", so I
guess 12-13" per fan is about as big as I can go.
I'm thinking about going to a junkyard to get some used fans though, as I imagine they'll be a lot cheaper than the new fans I'm seeing at places like Summit.
Does anyone have any tips on what sort of vehicles would have fans of this size? I guess this isn't such a Pontiac-specific question, but I'm not sure where else to ask.
Any other tips would be appreciated as well, since this is my first electric fan setup. FYI, I'm planning on buying an adjustable thermostatic switch to have the fans turn on somewhere around 160F, I will be using a fan shroud, and the reason I'm doing this is because after I got the engine rebuilt and took the old water injection (ugh!) unit off, the car gets hot enough to be undrivable in the city.
Thanks,
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Amrit
ICQ: 3173735
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After screwing around with generic electric fans on the vette I bought a Flexalite Model 295 setup for the T/A; a 4600 cfm dual 13 inch fan unit that comes assembled in a shroud. Installation was pretty easy and it comes with a VSC to modulate fan speed based on temperature. I added a Painless Wiring fan clean up kit for a 170 degree water temperature switch. The only problem with the water switch is it bypasses the VSC so the fans run at 100% speed. If you are going to run electric fans plan on upgrading the alternator to at least a 100 amps. But the most important thing to do is make sure the radiator is a 4 core and it's in good shape. All the air in the world ain't going to help a plugged radiator.
As far as performance, the wife and I made a total of 37 passes at Indy last year running the 100 shot and water temperature never went above 180 degrees.
Fans - $400 Alternator $125 Water Switch $25 New 4 core Modine factory radiator $200
If you don't want to spend the money, look for Ford (or Lincoln) big car variable speed fans at the junkyards. I don't remember which models but they seem to work for some people. You'll still have to upgrade the alternator and make sure the radiator is up to snuff.
Dave
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poncho462 wrote:

Thanks Dave. $550 is a bit more than I want to spend, so I'll take a look and see what I can find out about those Ford fans. I got the radiator recored not too long ago (and yes, 4), so I don't think that will give me any problems.
Are you sure I'll need a >100a alternator immediately, or is that just to allow for more electronics in the future? I just installed a stock replacement 63a alt a year or two ago, and hadn't planned on needing to upgrade so soon.
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Amrit
ICQ: 3173735
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Current draw will depend on the fan. My T/A has A/C so in the summer the 63 amp alternator wouldn't keep up. The Flexalite pulls 30 amps at 100 percent speed but the Ford fans may have a lighter current draw (that's the nice part of the variable speed fans). I'd find a fan and install it and go from there. The T/A voltmeters are fairly accurate so it should give you a good indication if the alternator isn't doing the job. I tried a Caddy 73 amp unit and it couldn't keep up with the dual fans. The voltmeter normally indicated around 14.5 but when the fans came on it went to 12 volts cruising.
If you look at some of the electric fan sites you'll see that they recommend over 3600 cfm or so for anything bigger than a 350 SBC. A Pontiac retains a lot of heat so you'll need the air flow to keep cool in the summer. I'm running aluminum heads and moly rings so overheating is a big no no. That's why I spent the money to keep the engine cool.
Dave
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poncho462 wrote:

I see. I'll keep an eye on the voltmeter after installing, then. I already have to keep an eye on the damn temp gauge all the time, heh.
Thanks again.
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Amrit
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Are you sure the shop correctly assembled the water pump and divider plate? A common problem with rebuild Pontiacs done by "shops"(especially ones that primarily do worthless Chebbies) is that they forget to reinstall the divider plate tubes and rubber O rings into the timing cover or the entire water pump divider plate all together.
My 455 HO runs 190-200 degrees all day long with the stock 19-1/2 inch flex fan and radiator shroud. When I bought the car somebody had installed an aftermarket 17" fan and it would overheat all the time.
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Dennis Smith
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Dennis Smith wrote:

The shop didn't handle accessories and such, so I'm the one that put the water pump on. I've removed the water pump and put it on a couple of times in the past, and haven't ever been left with any extra parts, so I don't think there's anything missing... ;)
But yeah, I'm confident that I've reassembled it correctly. I remember that I put the tubes and O rings in the way they work when I removed it. Should be fine, unless they were somehow in the wrong way from the previous owner (although I don't think it's possible to fit those in there backwards or anything)?
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