I have put a 17" flex fan on my car with a 2" fan spacer. My buddy has a 1980 Impala sitting in the back of his property that I can basically take anything I want off of. So I was looking at the fan shroud. I noticed a couple of things. The upper mounting pattern is the same as my car, and the shroud is pretty deep. I have removed the upper piece, and done a test fit on my car. I found that the shroud would physically fit if it was not so deep. I can cut an inch or so off of the back of the shroud (there is plenty of room) and if would clear the accesory brackets.

Question: Would this be an efficient setup? I notice on many older stock Chevys that the fan is right on the outer edge of the shroud, not 2" inside....

I am thinking it will work fine, just looking for some opinions I guess.
Thanks

 

There's no reason it wouldn't work, as long as the hole on the shroud has the same center as the fan. That is, if the radiator isn't up higher or down lower in the one car than the other, compared to the fan on the engine.

Doesn't much matter how far into the shroud the fan is.

Your cooling sysem will be vastly more effective and will consume far less power off the engine if you get rid of the "flex" fan and put a good-quality new thermostatic fan clutch and the stock fan back on it. That thing is probably costing you 6-8 RWHP.

 

I think i am going to yank the clutch fan off the impala also, we'll see how everything works...

edit: IIRC my buddys clutch fan setup pulled WAY WAY more air at idle then my flex fan. this is normal, correct? and at 2000 RPMs the cltuch setup pulls way more then this flex fan of mine too.....

 

Well, I could not get the shroud to work. After after removing my head from my ***, realized that I cant take the clutch fan setup from the Impala due to my CCW waterpump.

 

Details...

Is your "flex fan" reverse rotation?

Yes it is normal for a good quality fan with stiff blades to pull more air than a flex one. However, with a thermostatic clutch, it will only pull air when the air passing through the radiator is warm wnough to require cooling. Unlike a continuously connected flex fan, it disconnects itself when there's no cooling work to do... like when cruising down the highway or when the motor is cold. Then when it gets hot, it blows air like a mother.

What about the shroud? Does it line up? That at least could maybe still be useful.

 

Yup, my flex fan is a reverse rotation. Part number 17617 on this page. I chose a Derale Heavy Duty one, because of a member on ChevelleTech who had talked to some engineers at Derale. Although I love HP (who doesn't) I don't think I mind losing a little bit to this fan. I needed a fan and was broke at the time. I have a couple of friends who have thermal clutch fans, and both of them will start up their cars in the morning and the fans will be pulling away. The shroud will only work if I drilled new holes and cut away so much material that it would defeat the purpose. So it looks like a will be buying a 3rd gen F-Body shroud (no big deal I got a deal already) and keeping my 17" Flex Fan for the time being. I currently have a 2" spacer, how far away from the radiator should the front of the fan be?
Brady

 

The typical clutch fan will let go after a minute or 2 of locked-up operation when cold. They about always do that when they're working right: roar like hell for a couple of minutes, then suddenly shut up. You'll also notice, their engine RPM goes up when that happens; a demonstration of how much power a fan can consume.

With a shroud, it doesn't matter so much how close it is to the radiator. It will actually work a little better back away from it. Without a shroud, you have to locate it as close as possible, so that there's no air coming in from around the edges of the fan, but rather it all has to go through the rad to get to the fan. The shroud takes care of that. So, I'd recommend doing away with the spacer once you get the shroud in there.

 

Does the spacer put any extra strain on the water pump bearing? I will see how the fan's location is compared to the shroud with and without the spacer when the shroud gets here.
Thanks
Brady

 

I've got a thirden fan shroud if you want it. It may be easier to go junkyard though.