The Stovebolt Site Forums The Shop Area Engine Shop Electric cooling fan question

Hi everyone, am replacing the 250 inline six in this truck with a stock 400 small block chevy.

http://rides.webshots.com/album/556276729WcbaUB

The guy that built my radiator said that the radiator would cool a 454 big block so Im good on that account.

I plan to run an electric cooling fan along with the belt driven one.

My question is - Do electric fans work better on the outside of the radiator or behind the radiator on the inside?

Any suggestions or favorite name brands anyone would recommend?



Thanks for the help:

I dont see how you could put an electric fan on the engine side and still keep the engine mounted fan. I've also heard that you dont want two fans, one inside and one outside, they suppossedly dont work well together. Keep the engine mounted and get a shroud, or lose it and put a good electric fan on. I think its better if they pull through the radiator like original, but I dont know from personal experience. I'm sure someone who has done this can give more insight. Good luck.
Jeff

I plan to run an electric cooling fan along with the belt driven one.

Why?

Mount fan such that as truck is going down road the fan does not reverse rotation when the motor starts. Pretty hard on motors.

Dan Bentler

I plan to run an electric cooling fan along with the belt driven one.

Why?

Thats a good question,

When its 80F here and I take the truck on the hi-way and do 60 MPH I have to really push the little 250 hard because of all the wind resistance that the truck has (they weren't very wind resistant in the teens) , thus by working the engine so hard and the restriction of the front bumper to the radiator my temperature slowly starts to rise to about 200F with a 190F thermostat.

My theory is that the 400 wont have to "work" the way the 250 does at 60 MPH and that by putting an electric fan in front of the radiator that it will help scavenge more air into the radiator core on those occasions when it is a hot sunny day.

I have about 10 inches of space between the front bumper and the radiator to scavenge air.

Im also considering on putting vents in the firewall to blow hot air into the cab -I always thought that the hot-rod Model A guys took off the side panels to the hood to show off their V-8 engine, which they did but it also enabled more air flow through the radiator.
The narrow hood makes it difficult for the air travelling through the radiator core to escape the vehicle.

All in good fun though, nothing stimulates the mind like an honest challenge.
Here s better photo of what Im working with, I hope that I dont have to "open up" the front bumper.
http://community.webshots.com/photo/fullsize/2229304100099716915TmVnzC

Hope everyone had a Happy Thanks Giving.


Its only a gambling problem if you lose

Above 40 mph fan choice is easy - you don't need one at all. If it runs hot at 60 the problem is water circulation.

I thought you were serious until you wrote, "Im also considering on putting vents in the firewall to blow hot air into the cab".

There is a reason they call it a fire-wall.

You will read everywhere that pusher fans do not work as well as fans pulling from behind the radiator. GM doesn't seem to agree with that.
My '87 Vette has an auxilary pusher fan directly in front of the regular fan. It was optional or standard on Z51 optioned cars.
My '67 292 has the original 4-blade fan and no shroud. When I installed the AC I simple added an electric pusher fan that came from a '94 Cadillac deVille.
Look in the wrecking yards. You will find everything from Mercedes to mid '80s GMs with pusher fans.

I used a Flex-a-lite " pusher" type electric mounted on the outside of the radiator, and kept the belt drive fan on the inside. I am running a 327 SBC, and there is not room for both on the inside. I am using the stock '40 radiator which I had rebuilt. The electric fan is on an adjustable sensor so it doesn't kick on until 190*. Cooler months / evenings, electric hardly runs. In the summer, especially in traffic, electric is a must - keeps things under 200* at 80*F in stop & go traffic. Only issue I have is if I run the truck on the freeway ( stays cool ), then come off the highway into bad traffic - she heats up pretty fast, and even electric fan has trouble keeping cool.

Why run an electric fan? Its "my" opinion that prior to 1955 most of us that run a V8, our engines set lower in the frame and, depending on the bottom radiator connection, we are not able to run a bigger mechanical fan. I ended up having to use a 14" flex fan.
Its just not enough when in traffic or parades. Like Bruce says, runs nice and cool on the highway but once in traffic it heats up. SO, I put a small pusher fan on my 37. It helped but no cigars when in hot waather and traffic.
Next, I decided to go aluminum. Put it on and even without the electric it does run cooler but still, after a short time it will start climbing as it did in the Vetrerans parade a couple weeks ago.
So, I will either reverse the blade on the small fan I have and make it a puller...I have just BARELY enough room for a 12/13" electric, OR I'm leaning to buying me a high CFM puller fan and do away with the mechanical fan. I'll decide this winter!!

Ive got some options and a little room to work with as well, whether I go with one fan or two.

I just dont want to have to "open" the front bumper, no big deal if I do though.

The fire-wall vents would be put in place to allow air going through the radiator to escape the vehicle, narrow hoods can be a bit claustrophobic, similar to setting the engine in a box and not allowing air to escape, I dont think Ill have that problem with the 400 V-8 because there is such a long distance between the radiator and engine that should allow air to escape after passing through the radiator.

Something else that Ive thought of many times with is that with the integrated cylinder head that my 250 has, the sending unit is in the thermostat housing and would be for an idiot light, I would guess. I dont think this is as accurate of a reading as senders placed in the cylinder head with actual gauges.

If all else fails then Ill do what they taught me in Australia,
Sit down and open a cold one.


She'll be alright mate

you have a belly pan under that truck? how do you think the air that comes in the front opening gets out of any later vehicle that doesn't have the hood side louvers you have??? early rodders didn't leave off the hood sides for better engine cooling, they did it so you could see how cool the driver was

Bill

MMMmmm, would it ake any difference to just leave the inner fenders out?? Just a thought.

Either leave the inner fenders out or put more louvers in them, Alvin.

I have been fighting heat in the cab during the summer months. Of course, it's fine in the winter and I don't even need a heater. In the summer, my a/c can't begin to cool the cab unless I'm on the highway. It's a real problem.