[footjoy]

I built a 40 ford coupe SBC with a walker radiator and a walker electric fan and shroud
The car ran cool and great no problems. Well I put a vintage air on the car and the car ran 210 which sbc didn't like.

I messed with everything and I called fan company and he asked what model I had I told him and he said they had changed the design. The old design did not let air out of the shroud so what they did on the new design was trim a inch off the bottom so the hot air could escape. I did that and the car never got over 185 the rest of the time I owned it.

So I am not saying to cut your shroud but it does make sense to back the fan up so the hot air can escape the shroud and have a flow through air.

Think about it, maybe your air is not escaping the shroud.

Greg

[Scarebird]

How close to the radiator was the fan? Maybe if you got too close you set up a rotor effect - essentially just stirring the air instead of pulling it through the radiator.

[Engine-Ear]

Originally Posted by Scarebird

How close to the radiator was the fan? Maybe if you got too close you set up a rotor effect - essentially just stirring the air instead of pulling it through the radiator.

Agreed - That is the term I was looking for!

[Old Tin Indian]

Engine-Ear.
Here's that book you mentioned earlier.

[rexs73gto]

The fan was about 1 1/2 to 2 inches away from the rad. the 1st time, & now it's out at the edge of the shroud & cooling fine.

[Old Tin Indian]

well, i've been doing some experimentation on this cooling system still, again, whatever. reclearanced the impeller to plate to about .045".
moved the coil spring on the clutch fan about 1/8" ccw (from another post)
and sealed the radiator to the shroud. after 45 minutes of driving in 91* weather, it still heat soaked to 210*. no change at all. what i did notice though and i forgot about it, was the trans cooler on the radiator. it's a big cooler too.
it covers a lot of the radiator. i'm wondering if the load on this cooler is affecting the cooling of the radiator. i never thought of this before.
i do have airflow at idle because i put a blue shop towel in the grill and it sucks it to the radiator. now i have to figure out what to do with the trans cooler situation.
tony

[rexs73gto]

The trans cooler could be an easy fix just by using a little cooling fan on it & running it to the under side of the car so the air going under the car will go through it & cool it as it goes by. I've seen a few of them under the car near the trans pan.

[chrisp]

Originally Posted by Old Tin Indian

well, i've been doing some experimentation on this cooling system still, again, whatever. reclearanced the impeller to plate to about .045".
moved the coil spring on the clutch fan about 1/8" ccw (from another post)
and sealed the radiator to the shroud. after 45 minutes of driving in 91* weather, it still heat soaked to 210*. no change at all. what i did notice though and i forgot about it, was the trans cooler on the radiator. it's a big cooler too.
it covers a lot of the radiator. i'm wondering if the load on this cooler is affecting the cooling of the radiator. i never thought of this before.
i do have airflow at idle because i put a blue shop towel in the grill and it sucks it to the radiator. now i have to figure out what to do with the trans cooler situation.
tony

Ditch the clutch fan & get a nice flex fan

[Old Tin Indian]

has anyone ever used a transmission cooler like the one pictured and with what results? i'm thinking of removing the hayden 18,000 lb GVW cooler on the front of the radiator and installing this new cooler pictured towards the bottom of the radiator to open up much of the surface area of the radiator to the airflow through the grill. i've done everything else. i'm hoping this works. this is the only thing i've never addressed because i never thought about it.
any thoughts are well taken.
thanks
tony

[Chicagogoat]

I would check the temp at the trans cooler when temps are running 205 or better with a good instrument like a T-couple type that you shove into the coils. See if the trans is overheating, those rad mounted trans coolers are the most effective for the street I gotta say. Have you tried running a flex fan? It's cheap enough and worth a try.

[69Farburd]

Originally Posted by Old Tin Indian

has anyone ever used a transmission cooler like the one pictured and with what results? i'm thinking of removing the hayden 18,000 lb GVW cooler on the front of the radiator and installing this new cooler pictured towards the bottom of the radiator to open up much of the surface area of the radiator to the airflow through the grill. i've done everything else. i'm hoping this works. this is the only thing i've never addressed because i never thought about it.
any thoughts are well taken.
thanks
tony

Tin, I tried using one of those and my trans got very hot. I think they say they are for racing only. I replaced mine with a Hayden mounted to the hood latch support about 1 1/2 inches in front of my AC condenser so the air could go around it. My engine temps stay cool (aluminum radiator) but I'm not sure what the trans temps are doing.

[Old Tin Indian]

I'm in the process now of deciding where I want to move my trans cooler.
I might try to go from the grill side of the radiator to the fan side. I've seen on a number of websites that this is the best place for it. But it looks like I only have about 1" between the clutch fan and the radiator. And that's with a 1" fan spacer on it. i have some measuring & experimenting to do.
But, rest assured if there's a problem, I'll find it. ( I always do)
Tony

[68blackbird]

So to break this down in simple terms. Tightening the spring will lower the temperature at which the clutch engages?

Rich

[rexs73gto]

If your fan is at 1 inch from the rad. it is to close & needs to be backed up away from it so the air will have a chance to flow through the rad. Having the fan that close we have figured out that the air is being trapped & pushed away from the shroud & not allowing it to be pulled all the way through the rad so it will cool. If you back up your fan so it is at least 3 inches away from the rad. you temps will come down & you will not have a hot car again. The air has to have room to be pulled all the way through the fan & not stopped at it.

[Old Tin Indian]

I understand what you are saying, even though I don't know why it works and I also understand what the turbo-prop guys are saying too. Make sure the fan is right into the shroud. But, the GM engineers are not fools. By placing the fan 1/2 to 2/3 into the shroud has to have it's benefits too. I've gone to several car shows this year and made it a point to look at this very thing. Almost all of the cars with shrouds, GTO's, Chevelles, Gran Sport's, 442's etc.. have the fan part way in the shroud. No overheating or running too hot. I'm running a 455 (w/about 100 hp more than stock) in my '67 GTO with the stock 400 timing cover, fan spacer and clutch fan. If I don't shut the car down after about an hour of driving, it just keeps creeping up. I don't let it get much beyond 220*. (obviously never ran hot w/stock 400. never over 185*)
I'm changing the trans cooler to a Derale 10000 series. Smaller but more efficient. I'm taking the Hayden cooler off of the radiator and putting the new cooler towards the bottom of the radiator, part of it behind the bumper on the grille side and exposing much of the radiator to good airflow, hopefully cooling it much better without the load of a hot trans cooler on it.
I'm also going to install another high flow thermostat and new anti-freeze.
Will keep all posted.
Tony

[Willshire]

I thought having the fan partially in the shroud, used the shroud as a kind of funnel, creating, not really a vacuum, but kind of. Like if you put a vacuum cleaner (or fan) around the end of the funnel small end you would suck in all of the air in the funnel cone but if you shoved it half way into the cone, you would only pick up the air in front of the vac hose and part of the funnel behind the hose would just be turbulent air?

Mine is partially in the shroud and my shroud is also spaced of the rad a 1/2". 180* all day long except at long lights lol

[Old Tin Indian]

the fan is pitched to pull air through the radiator from outside of the grille.
the shroud acts as a wind tunnel pulling air through the radiator cooling the fluid down.
some of the best shrouds came on the early 70's grand prix's & monte carlo's.

[70pontiaction]

Clutch-style fans pull the air pretty much directly thru them and straight back towards the engine, with a very slight spreading of the air column. That's why they work well when most or all of the fan is in the shroud. Old factory FIXED fans are usually this design.

Some flex fans (like the stainless-steel flexible blade style) work pretty much the same way - pulling the air mostly straight back towards the engine. They usually work well about 1/3 inside the shroud so that when they flatten out they are about 50/50 - half in and half out. AND they have a tendency to cut your fingers......

Other flex fans (like the semi-rigid fiberglass or plastic style) throw the air directly to the outside with only a slight pull towards the engine. This style would work well the way Rex describes his working - either outside (barely) the shroud or with a minimal amount inside. That way they would create a vacuum that would pull air through the shroud and radiator by removing the air just outside the shroud and pulling the air inside the shroud and consequently in front of the radiator back to replace the air they have removed.

My guess would be that if Rex had this style fan on the car with NO shroud, the air being 'blown' by the fan would move outward rather than towards the engine. That would be the first thing I would do if my car had a good cooling system that didn't seem to keep up - determine what my fan was trying to do and then figure out how to best help it accomplish the goal - in shroud, out of shroud, or 50/50.

It makes sense that if a rigid-style fan was contained completely inside the shroud, very close to the radiator, it could mainly cause the air to swirl inside the shroud and any cooling would be from the built-up force of the excess air in front of the radiator cause by forward movement of the car. This set-up would definitely run hotter when sitting still at a light, and would probably work fairly efficiently WITHOUT a shroud and close to the radiator.

So, I guess, out here in the real world, you may have to try several different setups to get the results you want. But, isn't that one of the challenges of our old Pontiacs anyway?

Side-note: I bought a GTO years ago that would run cool sitting but overheat as soon as you started driving. We discovered that it had a brand-new stainless blade flex fan made for reverse rotation on it.......running backwards.......ouch......

Fan kind of made a funny sound, too. Especially when you revved it up........

Of course, your mileage may vary.........

[robscar]

I used a trans cooler similar to that on my 67 GTO. I mounted it in the frame c channel. Used one of the cross member bolts for the front and might have drilled the other holes, do not remember. It worked very well. Get some quality hose and fittings from a hydraulic shop and you should be good.

[rexs73gto]

70, my fan is a flex fan made of the thin alum. with the steel center hub. It works very good where it's placed with it right at the very front edge of the shroud. Also I forgot to mention that the shroud is the type that closes off the entire rad. & the only opening is where the fan sits.