electric fan 40 ford what cfm

I would be more concerned with how many amps if you are using a 6vt or 12vt generator. If you are running a 12vt alternator look one the comes closest to matching your radiator size. Contact some of the manufacturers tech people and vendors. They will be glad to help you pick the right one for your car.
 
You have to consider the amperage on your system, a fan can pull from 25 to 40 amps, do you have a large enough alternator to supply it? I went with a be cool, made in Italy.
 
If the electric fan don't push enough air to improve cooling it can also block cooling air that is comming in from forward motion and the original fan. I went on a short tour Thursday and returned today and visited a guy with a 36 that had cooling problems before installing Skips pumps. He didn't have all the equipment needed to do a good test. I put a $10.00 Lasko box fan from Wal-Marts on my 35 roadster hanging from a wire from the grayhound against the grill on Wedsday afternoon at 4.00 PM. It was in the 90s and I ran it at a fast idle for 45 minutes and the temperature stablized at 164 on one side of the head on the hump behind the water pump and 167 on the other side. This was so I would have a idea of what the temperature should be on the 36 under the same conditions. We got to the 36 about 2:00 PM on Thursday after eating several dozen crabs and a few pitchers of cold beer, put the same fan on in the same position as was on the 35 and ran it for 30 minutes and the temperatures were pretty much the same as the 35 and not moving up and it was well over 90 out. This car had a 6 volt electric fan on it also that was NOT running during our test. I left the car running after the test, removed the electric box fan from in front of the grill to see what the 6 volt fan would do to help the cooling. The 6 volt fan was no help compared to the box fan which is not a big fan. The temperature started to climb in minutes with the 6 volt fan running and we shut it off in 5 minutes as the temperature got up in the 178 range and raising. I would say forget the electric fan unless you have the battery power to run a large one. The box fan simulates the air pushed through the radiator when driving down the road. None of these old Fords want to Idle for long periods of time in 90 degree temperatures, the stock fans don't provide enough air but when moving the air comming from forward motion does a good job. My 39 convertible never got over 180 in the 150 miles on Thursday and another 150 miles today in the mid 90s. The only cooling improvements being a 4 lb pressure cap and Skips pumps. G.M.
 
Well, heres what I'm running, a GM 100 amp alternator, a Ron Francis circuit box, a 40 amp Spal pusher with no shroud, an aluminum Griffin radiator, a trans cooler to keep trans heat transfer into my radiator to a minimum, a 180 thermo stat, a 50/50 mix of Prestone for aluminum radiators, engine is a 351 W has air conditioning, engine idles at 1100 rpm, has a healthy cam, has an electrical auto thermostat that turns it on at 180 at the drivers cylinder head port, has a temp gauge under the hood, has a temp gauge in the dash, has an in car by pass switch so if I see trouble I can respond, I can let it idle for 45 minutes at 1100 rpm in this schweaty weather we are having and it never goes over 180, The radiator is not coated or painted. This system is copied off my buddies outlaw 600 inch hemi ford, she runs pump gas and a 500 shot of nitrous, easily 1500 hp, stays as cool as a cuke in 95 degree weather. He runs the aluminum radiator and the pusher.
You need to look at your system as a whole, sure you could have a 12 volt system but you may only have a 50 amp alternator. Too many guys look at a car as a bunch of single independently operating systems, thats a mistake, you have to look at a car as a group of integrated systems that operate as one unit, a machine. It makes it difficult to give some one advice towards a cooling system without knowing their car.
In all honesty, if you have a stock engined car, a good quality radiator that has been properly maintained, a well fit fan shroud a quality fan, and a system maintained to the manufacturers specs, you should not need an electric fan, but if you have modified anything you may need to address other items as all are affected. That said, a "12 volt system" doesn't give us much to work with, so what do you have?
 
have stock motor with 12 alternater have electric on car now temp runs 3 quarter on gauge do not no cfm think it is to small is 3 quarter normal on 40 ford
 
First you need to determine what temperature it is when the gauge reads 3/4s. These stock engines should run in the 170 to 180 range when it's in the mid to upper 90s outside. This is driving down the road at speeds to 75 MPH with the stock fan. They will run a few degrees cooler in the 50 MPH range. The temperatures need to be taken on the head at the hose outlets with a laser pointed thermometer then you can compare that temperature with the gauge. The gauge temperature is only one side of the engine and radiator temperature is a mixture of both sides. The block is 2 seperate cooling systems and not connected inside, only in the radiator so it is important to know what each side reads and they should be within a few degrees of each other. I drive a lot times for distances of over a 1,000 miles in 2 days at 65 to 70. The only problem is in 90s temperatures, the temperature will get up over 200 in about 10 minutes of idleing if you get stuck in traffic. As soon as you get moving the temperature will drop right back down in the 175 range in 1/2 mile. I see no need for an electric fan on my 35, or 3- 39s I drive. I use Skips high volumn pumps and either a 4 lb pressure cap or Skips 3 Lb pressure valve on all my drivers with the coolant filled up near the top of the filler neck. I just drove the 39 convertible 1,200 miles in 2 days with the temperatures over 100 and as high as 110 both days and the coolant is still up at the top of the neck. There are 3 things that improve the cooling on these engines. A larger amount of water (filling the system), more water flow or more air flow. Any one of these will improve cooling. On my 39 P/U I have a stock radiator, Skips pumps, 4 lb pressure cap, industrial (quiet) 6 bladed fan and a fan shrowd. I ran this at a National Ford V/8 show at a fast idle for over 2 hours when it was over 95 degrees and it never got to 180 and if I raced it up a little once in a while the temperature came down a little. You also need a wetting agent in the coolant to remove hot spots, we use 2 gallons of perminant anti-freeze, 2 bottles of Purple Ice and a large bottle of Barrs aluminum stop leak in all old Fords. Someone needs to make a GOOD replacement fan and with a pressure caps and more water circulation these cars can be driven anywhere, anytime. When the engine is cool it is cooler in the car, the engine burns less oil and the oil don't get black. G.M.
 
How hot is hot? After reading this post I'm going to go along with GM on this. It is very difficult to address heating issues if the sole basis of a temperature reading is made using stock range style gauges. There is nothing to relate them to, how cold is cold , how hot is hot? Without doing some scale comparison via thermometer or heat scan gun your vehicle could be operating perfectly fine. If it is not boiling over you know that it is less than 212*. Your stock crank driven fan should be adequate even for temps in the 90's if you have a good clean radiator. Before you go spending a bunch of money on retro fit fans calibrate the reading on your dash gauge with a digital reading gauge to determine the actual temperature.
 
I run a 2700 Cfm fan on my 53. If you have A/C the minimum that is recommended is 2000 cfm. I only use the fan with the a/c on if I get stuck in traffic and keeps the temp around 170. Normal running with a/c on is 160. I gave up on fan relays, now use a 50 amp toggle switch. The car is 12 volt and I use a 100 amp alt
 
Have a 48 with 8ba engine all stock rebuilt with reds headers and exhaust 180 stats. runs 180 on hot days ie 90 plus idles about 5 deg. same temp. before engine change ran hot and got hotter the more it ran all my trips wree 6 mile or so one way. When i changed the engine i rebuilt the original 8ba pumps and had the rad recored same sizeetc. but the rad shop told me the new core was a better design,i guess they were right. So what Dick Sapadaro says about "a good rad" is real important! It also has the original fan 4 blades
 
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I think you are running a 12-volt alternator - if you are running a stock gauge, do you have a reducer for the gauge? If not, you are showing 3/4 hot when you are probably running quite cool.

On a temp basis get a small pair of mech or elec water temp gauges and install - see what temp you are running and then determine whether you are running hot.

Same thing happened to me and this is what it was.

Keep us posted on your progress ....
 
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