What would you guys recommend to seal the gap between the radiator and shroud? It is about 1-1/2 inches. I would like to use some of the material that they use on the newer cars to cover the area between the grille and the core support. I can't find any where to buy it. It's probably because I don't know what the material is called. Or I could try to make something out of sheet metal.

I tried to add a photo, but the forum wouldn't let me. It kept saying the the attachment was too big. I even compressed the image to 110 kb and it still tells me it is to big.

I guess it did add it.

sheet metal might be pretty easy to fab/bend/cut/drill holes in. You might Google your Q on the other material you mentioned & see if something relevant shows up.

I would likely just use sheet metal too. Fiberglass might give it a cleaner look if done correctly.

I would simply re-bend the shroud brackets to where they attach to the rad support. If i couldn't re-bend them, I'd toss them out and bend new brackets to get a tighter fit. There should be no reason at all to use fill material.

and by the time you all of the above you have bought and used the right shroud for that rad. is that a Champion? look on their site or Summit. you'll be hard pressed to get a stock/repro shroud to fit anything but a stock radiator.

what about the seal that would have been mounted to the underside of the hood, is that still there?

I tried several variations of a shroud on my car with undesirable results, then I made this aluminum shroud out of the kit that came with the Northern radiator and my cooling issues vanished, I can cruise all day when it's 95 degrees out.

Rather then filling the gap, the shroud needs to be closer to the rad. The fan blade should be 1/2 inside the shroud, and 1/2 way outside the shroud. Your fan appears to be completely inside the shroud, and could cause overheating at highway speeds (might be the angle of the picture though). Gene

Ding ding ding I do believe we have a winna

Look close between the radiator cap and power steering pump cap and you can see a fan blade. It is a flex fan and it is about 1/2 inch out of the shroud.

Just me I would toss the flex fan & use an MP thermal clutch fan with the most blades you can locate

Here's how I ended up closing that gap on my champion radiator with factory 22" shroud. I used some aluminum flat stock and some pop rivets.

The clutch fan I've got right now is a little deeper in the shroud than ideal. I'll likely switch to a fixed fan this summer as the clutch fan doesn't seem to cut it when stopped for a while. I may try a better water pump too.

I'm wondering it it is a water flow prob or airflow (or a combo of both). what is the pulley ratio? can you feel or sense good airflow at idle. I've seen some C bodie setups that have a tornado of air flowing

The water pump is in good condition, but just a stock replacement- not sure which one though.

Not sure on the pulley ratio. I could measure though. I didn't realize they made different diameters.

It seems to blow a bunch of air at idle. The cooling systems stays cools when driving, but even in the colder winter weather, temp starts to creep up when stationary. I've got a fixed fan on hand, so I'll likely toss it on when the weather warms up to give it a shot.

Part of your cooling issue is the fan is too deep in the shroud. This really hurts efficiency. As stated earlier a 50% or so immersion into the shroud will help improve your airflow.

Unfortunately, that can't happen without some major surgery. Wish it was different, but oh well. I'll make do.

I had a problem cooling my 65 Barracuda Formula S and could not figure it out for a long time. Then one day I decided to check the coolant (anti-freeze) concentration. It was almost 100% green antifreeze (Prestone makes a hydrometer like gadget that checks this). When I dropped the concentration to 50/50 things cooled down. I know it is a long shot, but it worked for me.

Mopowers, that is the way I'm thinking of doing mine. Thanks for the pictures.

And if you do it the same way Mopowers did his, you will also have overheating issues.

The shroud mounting method needs to be corrected. The Mopar Rad mounts the shroud slightly towards the front of the car, and the shroud has the cut out to clear the rad core. Any factory fan setup will place the fan at the same location. The only thing you could do is maybe cut a solid mount fan spacer in 1/2, if you have the required distance to use one.

Modifying the fan shroud so it sets at the correct location in relation to the fan is an easier, and a correct fix. Gene

You really think moving the fan 1/2" back relative to the shroud would make that much difference? I didn't realize it was that critical.

Just went out and looked. Looks like mine is about 2/3 in the shroud and 1/3 out- again not the ideal 50/50. I can probably get another 1/4" with spacers between the fan and clutch, but I highly doubt it would change much. I don't have a crazy overheating problem. The temp just climbs a little at traffic lights. May be the pump, or the fact that it's just a 17" fan, or combo of everything. Unfortunately, these Champion radiators have a poor design when it comes to mounting a stock radiator.

I can say that it cools quite a bit better than the 22" stock radiator I had before that was re-cored with a 4-row core. Of course, I didn't have any shroud on that one. Oh well, I'm pretty sure I'll be able to make this setup work one way or the other. Thanks for the ideas.

Like every design, there is always room for adjustment.

Personally, I would prefer the fan 2/3 out, rather then 2/3 in.
The shape of the fan and the shape of the shroud place the best distance at 50/50 fan in/out.

If the fan is in or out too far, it can either allow too much air to not be effected by the fan to pull air through the rad at low rpm, or it may reduce the amount of air that can pass by at higher vehicle speed, or higher rpm, or it may do both. Exactly how much too much is will depend on the car, the fan, the radiator, the fan shroud, and how many air "leaks" are involved.

Lets see if I can paint a picture of the whole air flow deal.

Picture the radiator support on your car as a solid wall. If you move that wall forward, all the air has to go around the edges of the wall. Now, we cut a square hole in the wall (opening for the rad), and move the wall forward. Now, some of the air hitting the wall, can go through the opening (and through your rad), and some of it still goes around the wall. Once the air has passed through the wall, it sort of just bellows out and moves away.
For fun, lets put sort of a funnel in front of the hole in the wall (the front of the hood, the fenders and headlight area, and the front bumper). When we move that wall forward, now all the air that enters the funnel has to go through the hole in the wall opening (rad opening) or it backs up until it can overflow the sides of the funnel. If the funnel isn't sealed to the wall very well, we will loose some air flow through those seals as well.

Well, we can't just leave well enough alone, can we? Lets all a tunnel and another wall (the inner fenders, hood, and the firewall). When we restrict the area where the air can flow, the air tends to move faster then the air outside the restrictions. fortunately, our tunnel still has the bottom open, until we stick a rather large rectangle block (the motor exhaust, frame rails and suspension) there. The restricted space around the bottom now will restrict the amount of air that can pass through our hole in the wall, but what passes through is moving pretty fast (and takes the heat away with it). The faster the wall is moving, the faster the air passes through our hole in the wall. Life is good!

It all works pretty slick until the wall stops moving. Now we have to create a way to get the air moving. Introducing the fan. If we mount that fan inside the tunnel (behind the rad) and pull the air through the rad, the tunnel effect still works pretty well, because the air still has to pass through the hole in the wall to get pulled through. If we mount that fan out in the funnel, and there is no air trapped there, is sort of directs the air through the hole in the wall, but a large amount can just circle around the fan. It still works, but is way less efficient then pulling the air from inside the wall.

So, the fan by itself helps a bunch, but what if the motor creates a lot of heat, and/or is larger or there are headers and other stuff restricting the air that can pass out of the bottom of our tunnel? If we surround the fan (fan shroud), and seal it to the rad and to the hole in the wall, we can really pull some air into our tunnel and force it back out the bottom. We dramatically increase the efficiency of our puller fan.

This fan and shroud may be great when the wall isn't moving, but what happens when the get the wall moving? The fan and shroud can become the restriction, if the fan can't move the air fast enough. The very thing that makes it work so well when the wall is not moving, causes problems when the wall is moving, and the faster the wall is moving, the bigger the issue the fan and shroud become. At some point, the fan blocks all the air it can't move, and the heat starts to build. Somewhere we need to make concessions for the fan and shroud efficiency, because it still has it work if the wall is not moving.

Some of the compromises made are the difference between the blade diameter and the shroud opening. They (those way smarter then me) can determine how much difference those two diameters can be to fit their design perimeters. They can reshape the edges of the blades, and reshape the edges of the shroud. They can change the position of the blade in the shroud, or they can make provisions in the shroud that allow higher velocity air to pass through the shroud (some front drive car have neat little doors that can lift open to allow air to pass through the sides of the shroud, away from the fan blade). The largest problem is that they made their designs to fit a set of standards that may, or may not agree with our set of standards, and on top of that, we have probably altered the components they based the designs on.

Everything on an automotive cooling system is a set of compromises. The motor creates heat, and a certain level of heat needs to be maintained for the motor to function at its best performance level. We have to dissipate that heat when it reaches a certain temp, and we generally do that through heat transfer into coolant, and then from coolant transfer through moving air, and we have to do that through vastly varying outside air temps and conditions. We have simply covered some of the air flow part of this complex process. Gene