fan shroud

[1966FLEETSIDE]

when i got my 66 it came without a fan shroud.it has a 327,do i really need one?it still has original harrison radiator.i live in cool country kinda by the coast where it doesnt get hot often .but just concerned.

[LVPhotos]

It makes the cooling system more efficient. But if it's not getting hot to each his own. I don't have one with a 406 small block in the desert. Plans for electric fan soon though.
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[64shortbox]

In the era our trucks were built most cars & light trucks didn't come with fan shrouds unless they had A/C. My 64 C10 has a 350 and Vintage Air installed and the only time it gets very warm is if I'm sitting in traffic or a long drive through line with the A/C on. I live in the California valley where the temps are near triple digits most of the summer. I am in the process of adding an electric fan from a Lincoln MVIII to make sure my truck stays Super Cool during the summer months.

[Rufton]

I don't like shrouds. I'd install bigger fan before shroud. Different strokes.

[jrobertop88]

I second 64shortbox, I also have a 350 without a shroud, and it does get hot on me when sitting in traffic for a while. Also thinking of putting in electric fans or maybe make my own...
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[Captainfab]

If you have a fan shroud, I would keep it in there. I see no reason to remove it, and a few reasons to keep it.

[Rufton]

I went to the effort of installing fan shrouds on two cars; feeling proud.
Temp gauge appeared to stay the same.
Soon after, car 1 fought back and I needed to work on H2O pump.
Was a pain installing factory correct shroud, so up in the attic it went.
Later I did maintenance on car 2 and I left that shroud off as well.
Back to square 1.

I have a lame theory that no shroud helps reduce underhood temps; that's my theory and I'm sticking too it unless global warming wins the battle

[HOTFUN]

All V8 models in the trucks had a shroud from the factory.

[63burban4x4]

the shrouds were not all round metal, as you might think. My 63 (original 283) had 3 straight metal pieces bolted to the inside of the radiator support from the factory. Someone here probably has a picture. I think maybe that style came along in 63?

[tincan1966]

Very seldom are fan shrouds installed or fabricated correctly. When used as designed they greatly increase the efficiency of the cooling sytem. The fan should only be approximately 1/2 way inside the shroud, with about 3/8" clearance around the fan. Also the shrouding or baffles in front of and on the sides of the radiator, that direct air thru the core, are as important. Stay away from a "flex fan"- they are most effective at coming apart, regardless of the HP gains they like to claim. My thinking- if your fan is restricting HP you can feel, your engine was junk to begin with.

Simply attaching a electric fan that runs all the time won't help, much either, you still need a way to direct air efficiently thru the radiator to cool properly.
Temperature that goes up and down, in cycles is not working correctly, either. When correct, temp will rise slightly above the thermostat temp, drop slightly after t-stat opens, then maintain a temp around 5 degrees of the t-stat specs.

In my '69 C30 I ran and aluminum replacement for the 4 core OEM radiator, w/ factory shroud, 17", 6 blade steel fan w/ thermo clutch and 180 t-stat. Never ran over 190 degrees w/ AC on, idling with a 427 BBC.

There's no reason a small block in these trucks should ever run hot with the amount of underhood space and airflow. Properly set up and properly tuned, you should have no problems.
When these trucks were built new they were not run like they are today, either, trying to run 70 mph. Leaded fuel, also helps cool the engine internally, by adding lubricity in the cylinders.

[Rufton]

I've worked on car w/ approx proper fan/shroud set up. First I had to fight shroud. Then I had to remove radiator for fan bolt clearance; maybe bolt/core wasn't OEM? My cars run fine on hot July days; YMMV.

Perhaps I'm Johnny out of step but I prefer working on no fan shroud cars.

Feel free to ignore my post

[tincan1966]

I misunderstood the post- I thought it was about cooling efficency, not easy of working on it.

Do you leave off the hood and fenders too, so you don't have them in the way?

Sorry I posted useful advise on properly/safely repairing vehicles.


Very few here seem to appreciate the years of knowledge on this site, that are trying to help people make safe, reliable repairs.

[Trsmotrhed]

Originally Posted by tincan1966

I misunderstood the post- I thought it was about cooling efficency, not easy of working on it.

Do you leave off the hood and fenders too, so you don't have them in the way?

Sorry I posted useful advise on properly/safely repairing vehicles.


Very few here seem to appreciate the years of knowledge on this site, that are trying to help people make safe, reliable repairs.

X2 with ya here. I almost have stop posting for this same reason.
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[Rufton]

Originally Posted by tincan1966

I misunderstood the post- I thought it was about cooling efficency, not easy of working on it.

Do you leave off the hood and fenders too, so you don't have them in the way?

Sorry I posted useful advise on properly/safely repairing vehicles.


Very few here seem to appreciate the years of knowledge on this site, that are trying to help people make safe, reliable repairs.

You are correct. That's why I said I'm Johnny out of step.
I just choose to be wrong on this issue.
Maybe I need to see Dr. Phil regarding shrouds

[mikie 1954]

When I was in high school I had a 64 chevy that came with a 283 v8 and no shrould , it would over heat if you let it idle very long. I now have a 64 gmc that had a v6 that I replaced with a 350 v8, it to will over heat at idle so I put a shroud on both and no more overheating.if you think that replacing belts , water pump, pulley , ect is that hard with a shrould wait till you have to replace the motor due to overheating.
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[T Smith]

Originally Posted by tincan1966

I misunderstood the post- I thought it was about cooling efficency, not easy of working on it.

Do you leave off the hood and fenders too, so you don't have them in the way?

Sorry I posted useful advise on properly/safely repairing vehicles.


Very few here seem to appreciate the years of knowledge on this site, that are trying to help people make safe, reliable repairs.

I'm with ya on this!




Another important detail is having the side seals to the core support too, this brings in cool air from outside not just recirculating hot air from the engine compartment.

[Captainfab]

Another important thing to look at in the cooling system, is the condition of all the fins in the core of the radiator. If the majority of the fins are benmt over from careless handling, then the air can not get through the radiator, regardless of a shroud or the side seals. A radiator plugged with dirt and bugs will not allow air flow either, hence overheating will be an issue.

Many years ago, I had a '65 Impala with a mild 327, that had a serious overheating problem. I had a hard time making it home from work without overheating. After way to many times of that, I stepped back to look at my situation. Knowing that my engine, radiator and lack of a shroud, was not that much different than what was original to that car, I looked to see what was different. I discovered that most of the fins in the radiator core were bent over from many years of handling. So being basically broke, I could not afford a new radiator. Having more time than money, I spend a few hours with 2 small flat blade screw drivers, straightening all the fins on both sides of the radiator. I also blew all the dirt and bugs out of the core. I reinstalled the radiator, removed the flex fan I had installed (yeah I know) and installed the original 4 blade steel fan, with no shroud. The engine ran consistantly at 180-185 and never overheated again.

I'm not saying this to discount the importance of a fan shroud, but to prove my point of the importance of the condition of the radiator core fins in the cooling ability of the system.

[66customcamper]

I've had my truck 18 years or so and have never had an overheating problem without the shroud, BUT one reason I kinda would like to have one is to keep the cats away from the fan. Couple of them have gotten whacked pretty bad but luckily didn't kill them. It's an awful sound though. Now I pop the hood before I restart a warm engine when it's cold out.

[Sharps40]

My 64 had a plastic one from the factory...the 65 I6 did not. Both have a set of air dams between the radiator and cross mount to channel air in to the core and prevent it from going around.

The shroud, when installed correctly, moves more air thru the core at idle/slow speed when you need it most. To work correctly, the gap between the blade and shroud must be pretty small and the shroud must cover about 1/2 the thickness of the fan blades.

Too big a gap between the fan blades and the shroud significantly reduces the amount of air the fan can pull thru the core at low speeds and if the blades are not partly covered by the shroud ya get the same lack of suction.

Its a best practice to have more cooling capacity than you really need...sort of builds redundancy into the system/allows it to perform w/o failure in the worst of conditions. Saves ya a valve job or cracked head and other nonsense like a long sit on the side of the highway later.

[cortcomp]

There are a lot of factors that go into cooling (and there are a couple good flex fans too, but not the crap ones you normally see). Shrouds are important, as is running a thermostat (some leave them out, and that can actually cause overheating as well as never getting warm). Also contributing is timing, as well as carb and timimg setup. Slapping a smog era lean carb in with a smog hei unit in a motor with some oomph can cause heating issues too. Just fixing the timing on my rebuilt 455 brought temps down from 210 steadyz regardless of ac/outside temps/idling or cruising, down to 170 no matter what, rock solid. I know i tend to pour over the details, but addressing mixture, timing (initial, total, and curve), shroud, fan type, clean radiator and other details should garauntee that most any moderate motor will run cool. Now, not everyone is running a clean, rebuilt mild motor, i get that...but if you're starting with a solid motor withput a ton of hp, you should be able to keep your motor decently cool with factory parts, without electric fans, crazy expensive radiators, etc.
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[Rich 5150 69]

Originally Posted by 1966FLEETSIDE

when i got my 66 it came without a fan shroud.it has a 327,do i really need one?it still has original harrison radiator.i live in cool country kinda by the coast where it doesnt get hot often .but just concerned.

As long as you don`t wander away from the coastal coolness you shouldn`t have an issue, other wise run a shroud, here in the north valley at 110 temp that will be here saturday mine will run at 180, 6-blade fan, three row aluminum radiator, with the factory shroud...

[Brad54]

Remember, during these same years the bean counters at Chevrolet figured they could save $4 per car by leaving the front sway bar off of Corvairs. That didn't work out so well. The Corvair came out in '61, and by '64 they all had sway bars.

Does anybody REALLY think they'd have installed fan shrouds on vehicles if they weren't absolutely essential? Especially on vehicles that were only used as work tools back then like our trucks; vehicles that were on the farm or the work site, idling on hot days.

-Brad

[tincan1966]

Originally Posted by cortcomp

There are a lot of factors that go into cooling (and there are a couple good flex fans too, but not the crap ones you normally see). Shrouds are important, as is running a thermostat (some leave them out, and that can actually cause overheating as well as never getting warm). Also contributing is timing, as well as carb and timimg setup. Slapping a smog era lean carb in with a smog hei unit in a motor with some oomph can cause heating issues too. Just fixing the timing on my rebuilt 455 brought temps down from 210 steadyz regardless of ac/outside temps/idling or cruising, down to 170 no matter what, rock solid. I know i tend to pour over the details, but addressing mixture, timing (initial, total, and curve), shroud, fan type, clean radiator and other details should garauntee that most any moderate motor will run cool. Now, not everyone is running a clean, rebuilt mild motor, i get that...but if you're starting with a solid motor withput a ton of hp, you should be able to keep your motor decently cool with factory parts, without electric fans, crazy expensive radiators, etc.
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X2!! That is what I was saying in my post about "properly setup/installed and tuned"

[chevyrestoguy]

I am a big supporter of using the factory radiators, clutch fans, and shrouds.

GM had their act together back in the day, and too often, I see guys that are too quick to change out the factory stuff and replace it. I also see guys install their fans incorrectly by placing them too deep in the shroud. Yeah, it looks cleaner, but the fan blade needs to be half-in/half-out in order to work at it's most efficient. Guys pull their clutch fans off because they think that they're robbing horsepower. They remove the thermostats or put in one that's colder than it should be. They remove the shroud, a big no-no.

I highly suggest that you make every attempt to make the cooling system as efficient as possible by using a shroud, and if possible, a clutch fan and the right thermostat. Your engine will love you for it.

[Rich 5150 69]

Originally Posted by chevyrestoguy

I am a big supporter of using the factory radiators, clutch fans, and shrouds.

GM had their act together back in the day, and too often, I see guys that are too quick to change out the factory stuff and replace it. I also see guys install their fans incorrectly by placing them too deep in the shroud. Yeah, it looks cleaner, but the fan blade needs to be half-in/half-out in order to work at it's most efficient. Guys pull their clutch fans off because they think that they're robbing horsepower. They remove the thermostats or put in one that's colder than it should be. They remove the shroud, a big no-no.

I highly suggest that you make every attempt to make the cooling system as efficient as possible by using a shroud, and if possible, a clutch fan and the right thermostat. Your engine will love you for it.

As shown