[Carmine]

Hi everyone. I'm in the process of installing a 7 blade fan, new fan clutch and new radiator in my '71 GTO. I bolted the fan clutch and fan to the water pump to see how it might fit against the shroud. The shroud came with this car and when I was cleaning it, I noticed a previous owner had butchered the hell out of the bottom. This guy made me look like a beginner. I don't know why he did it, because the Mickey Mouse fan that was on it, was only 17" with plenty of room all around. I put this shroud into the framework and the depth of the blades into it, was good. About half in/half out. I spun the blade. Not hitting or contact. I noticed on the sides, the space between the blades and shroud was about 3/4"-1". I guess that might be good. The space at the top is where I think a problem might be. The distance between the tip of the blade and shroud is 2 3/4" to 3". I can't see how this is can be good or factory. Isn't this too much gap between everything?? Shouldn't it be fairly equal between the blades and shroud all the way around?? The shroud seems to fit fine. All the bolt holes line up. I don't mean to impose, but if someone could steer me correctly with an answer asap, I'd greatly appreciate it. If I need a new shroud, I'll order right away from Ames. I'd really like to get this car up and running soon. I've been fooling with it since Feb. Driven it twice and it's almost August. Really starting to annoy me big time. Sometimes I think about putting it out front with a fore sale sign and start again. Of course I would want one done like this was suppose to be LOL. Many thanks, Carmine.

[Carmine]

Maybe someone could take a look at the distance between their fan blades and the shroud. See if it's the same distance all the way around; especially at top. I don't necessarily need measurements. Just some idea of distances. Thank you, Carmine.

['ol Pinion head]

Can you post several pics of your fanshroud? A good pic of the drivers side top & passenger side looking from AC compressor area to the radiator tank would be best. Good chance it's not original, but some other auto manufacturers that has been hacked up to fit, unfortunately, have seen this before.

[Carmine]

Originally Posted by 'ol Pinion head

Can you post several pics of your fanshroud? A good pic of the drivers side top & passenger side looking from AC compressor area to the radiator tank would be best. Good chance it's not original, but some other auto manufacturers that has been hacked up to fit, unfortunately, have seen this before.

I do have one pic of the top area with focus on the fan blade and shroud. You can see quite a gap there. The side pics didn't come out good at all while in the car. Will take additional pics of it outside the car. I know you'll take my word for it, that the blade is about 3/4"-1" away from the shroud, on the sides. Measured several times. I think this is good allowing for slight engine twisting. I will post pics later. I have a suspicion that this shroud might be out of a full size Pontiac and they butchered the bottom to make it fit. Even though everything lines up properly and it looks like it belongs there, has to be a reason they did this, Carmine.

[72LuxuryLeMansLa.]

Originally Posted by Carmine

I do have one pic of the top area with focus on the fan blade and shroud. You can see quite a gap there. The side pics didn't come out good at all while in the car. Will take additional pics of it outside the car. I know you'll take my word for it, that the blade is about 3/4"-1" away from the shroud, on the sides. Measured several times. I think this is good allowing for slight engine twisting. I will post pics later. I have a suspicion that this shroud might be out of a full size Pontiac and they butchered the bottom to make it fit. Even though everything lines up properly and it looks like it belongs there, has to be a reason they did this, Carmine.

Carmine if that thing is "butchered order a new one. Give me a few minutes and I'll get some measurements from my car.

[72LuxuryLeMansLa.]

My fan is about an inch bottom and sides with about two inches top side. This is a '72 LeMans with clutch fan and Replacement shroud that was exact to the original. I ordered it from Ames. It pulls so much air at idle that if I have the hood up and fender covers on to work on it, I have to weight down the passenger side cover because it will get blown off.

[Carmine]

Originally Posted by 72LuxuryLeMansLa.

My fan is about an inch bottom and sides with about two inches top side. This is a '72 LeMans with clutch fan and Replacement shroud that was exact to the original. I ordered it from Ames. It pulls so much air at idle that if I have the hood up and fender covers on to work on it, I have to weight down the passenger side cover because it will get blown off.

OK Karl. Thanks. I did order a new one from Ames. Going to be interesting to see how the new one lines up, Carmine.

[Carmine]

Here are 4 pics of the fan and shroud. In the one pic, you can see the distance/gap at the top between the blade and shroud. The other 3 are of the shroud. The one will show the cut away bottom. On the lower passenger side corner, someone apparently put a piece in using rivets and fiberglass. You might not be able to see it. Crappiest job I've ever seen. Thanks for looking, Carmine.

[judgeman6970]

Stock GTO clutch fan is about 19.5" diameter(I believe)? What are you using? Also, you might want to check/replace your motor mounts. They're cheap, and they really help keep the fan from being too close to the bottom of the shroud.

[Carmine]

My fan is a 7 blade one that came off a Judge. Don't know the year. I believe it measures 19" or so. The shroud opening is 21". This should allow about 1" on the circumference between the blade tip and shroud, which would be about right. I'll check the mounts, Carmine.

[lust4speed]

Fan diameter looks small. Take a measurement from blade tip to tip. An A/C fan should measure 19.5" while a non A/C fan is going to come in at least an inch smaller.

Not apples to apples, but on my son's '65 2+2, there was a small section missing from the bottom of the shroud when we purchased the car, and overall condition of the shroud was a little tacky. So we purchased a new one just to improve the looks. The new shroud had the car running 10° cooler in traffic. Wouldn't have believed a small strip missing would have made that much difference, but it did.

[android 211]

My 72 TA had a chunk missing from one corner of the fan shroud. I got another shroud out of the junkyard and replaced it. The car definitely ran cooler afterward. the missing section was about 5 or 6 inches by 5 or 6 inches. I think they cut it because it made it easier to remove.

[Carmine]

Originally Posted by lust4speed

Fan diameter looks small. Take a measurement from blade tip to tip. An A/C fan should measure 19.5" while a non A/C fan is going to come in at least an inch smaller.

Not apples to apples, but on my son's '65 2+2, there was a small section missing from the bottom of the shroud when we purchased the car, and overall condition of the shroud was a little tacky. So we purchased a new one just to improve the looks. The new shroud had the car running 10° cooler in traffic. Wouldn't have believed a small strip missing would have made that much difference, but it did.

You had me wondering, so I just measured the 7 blade fan and old shroud. The fan is 19.5" long. The shroud measures 21" across and it's hard to tell exactly vertically because some is missing at the bottom. It's presently 22" but could have also been 21" at one time.
Went to a car showed yesterday, over 300 cars, and there were a few GTO's. There was a '71 there with their hood closed and no one around. Waited for them to come back and they never did. Next closest was a '68 and that shroud is different from mine. I noticed that his factory appearing fan was much smaller then the shroud opening. Without measuring, I think there was at least a good 1.5" or better between the blades and shroud. The fan also seemed to sit outside the shroud a little more then I've seen. Spoke with the owner and he said what you see is the way the car came from the factory. Hmmm.................The other GTO's were pretty much '64 and '65 years. I did see some other GM cars, late 60's-early 70's, namely Olds and Chevys, which had shrouds and clutch fans. In re. to fan depth inside the shroud, many were half in/half out, but I saw several that were much too deep or too far out in my opinion. Everything gives the appearance of being factory. I also saw a few shrouds that have what I describe as a hump at the top; similar to mine. Their top fan blade was a distance away from the shroud, like mine, and the sides were much closer, again like mine. Saw this issue mainly on the plastic shrouds, not the steel ones. I walked away from the show wondering if I'm trying to reinvent the wheel. Maybe what I saw is the way it's suppose to be. Possibly other then the repair work on my old one, that's the way it's suppose to fit the fan. I'll know for sure later this afternoon. A new one is due to arrive from Ames. I'll certainly compare it to my old one. Hope to install everything tomorrow and give it a try, Carmine.

[Carmine]

The new shroud arrived late this afternoon. I'll be installing it tomorrow. I did compare it to the old one. It's identical except for the bottom where a part of the old has been cut out. Since they are identical, the only thing I can think of, is maybe it was cut to allow easier installation?? Not sure what else it could be to prompt this. I presently have the fan blade bolted to the fan clutch and the fan clutch, bolted to the water pump. If I'm correct as to why the bottom of the old shroud was cut, is the shroud installation of the new, going to be difficult?? I'm sure others have put these together. Are there any trade secrets that can be shared?? Should the fan blade be taken off, shroud installed and blade put back on?? I haven't tried to test fit the new one yet. Any suggestions or experience would be greatly appreciated. Thank you, Carmine.

[lust4speed]

Normal procedure is to remove the fan clutch and fan as an assembly from the water pump. It's easier to slide the shroud in its general location and then install the fan assembly on to the water pump. After you get the bolts for the fan assembly tightened, you can then properly locate and secure the shroud.

Usually there is some adjustability in locating the shroud, and now is the time to center the shroud up to the fan. You also are better off allowing for more space at the top of the fan since the engine lifts on acceleration. I've had to use a round file and oblong the shroud holes on the earlier shrouds for a better fit, but that probably won't be a problem with later ones.

[Carmine]

I installed the new shroud and radiator today. I must have gotten extremely lucky because I didn't have to remove the fan. Bolted everything in and quite honestly, not too much has changed from the old shroud to the new one. The distances between the fan and sides, bottom was about the same as before. Surprisingly, so is the distance between the top blade and the shroud. I thought a new shroud might close this gap, but it didn't happen. It's obvious to me now, that this was all engineered this way and it's time for me to move on from it. Nothing is going to change. I do have a complete shroud now which is good.
Took the car for a ride to try out the new system. It was near 90 and humid here. I was a little disappointed with it. It reached operating temp. of 195 degrees and pretty much stayed there. I ran it hard a few times with higher speed and rpm's. I was hoping that the temp. would be about 180-185, but it didn't happen. I returned home and had the upper radiator hose leaking so I fixed that. I then started the car and let it idle and check for further leaks. It idled for maybe 10 minutes or so, and the temp. stayed at about 180 degrees. This is fine with me, but should the driving temp. be 195 degrees?? I thought it should be less. What operating temp. should you really start to become concerned about?? Thank you, Carmine.

[lust4speed]

Next you might want to pull out the thermostat and go for a drive. Have to dispel the Chevy rumor before going on - several of us have proven to ourselves that at least with a Pontiac engine, running a good working thermostat and no thermostat will give the same results. No better and no worse, and removing the thermostat for a test drive lets you know whether your current thermostat is functioning below par. While the thermostat is out, it's a good time to drop it in a pan of water on the stove and test when it opens up using your wife's cooking thermometer. You will be looking for initial opening and when and if it opens fully.

Another thing to check if you are using a fan clutch is the cut-in speed. I had purchased a new Hayden Severe Duty clutch fan and my temps were actually a little higher than with the old clutch unit. I took it back and exchanged it for another, and this time the engine temps were much cooler. Just another example that we can't really trust any new item anymore.

Last item is that the older shrouds produced best results with the fan just 2/3 inside the edge of the shroud with 1/3 out, but the later cars with the longer shrouds should have the fan totally inside the shroud.

[Carmine]

OK Mike. Something to look at. Thank you, Carmine.

[ZeGermanHam]

Others here with more knowledge will chime in, but I consider things to be A-OK if coolant temps are in the 190 range or lower. To me, 195 seems like nothing to worry about.

[72LuxuryLeMansLa.]

Originally Posted by ZeGermanHam

Others here with more knowledge will chime in, but I consider things to be A-OK if coolant temps are in the 190 range or lower. To me, 195 seems like nothing to worry about.

Actually in 1972 the Manual calls for a 195°F thermostat.......