Ok I will give the mechanical fan no shroud with the aluminum radiator a try. I am thinking also good at highway hot at low and idle speed. At the electric fan is a 2400cfm fan
Good, that should tell us which radiator is more effective.... a lower highway temp will be the indicator. If/when it's hot at slow and idle speeds, the fan/shroud setup will need to be improved.
So what’s the distance that the mechanical fan should be away from the radiator surface if you run a shroud to get hood air flow at highway speeds
Without shroud, it should be close, about 1". With shroud, it just needs to fill the shroud opening. At highway speeds, distance shouldn't matter.... the mech fan is mostly needed when vehicle speed is slow.
Please get get a proper shroud also! After seeing the photo below, I wonder if the car had a shroud originally? If not, then perhaps you don't need one? I also searched around and found a thread on teambuick.com where Tom "telriv" who probably has forgotten more about nailheads than I will ever know, gave the following advice. "Too little timing is just as bad as too much timing. With most stock NailHeads total timing should be about 30*-34* total mechanical. Add another 10*-14* vacuum advance & timing issues related to cooling should be irrelavant. One thing many forget is that the coolant can flow TOO fast & not have time to transfer the heat. In this case a restrictor needs to be installed. This could be as simple as a big washer in the upper hose to slow down coolant flow. Try different size openings in the washer. I use 5/8ths. of an inch. Just more thoughts." FYI
That is inadequate...you need at least 3000 cfm, but that is no guarantee. The original setup is usually the best
Like my previous posts. The original set with the condersor over heated and idle and low speed. The issue is either cool at low speed with the electric fan over over heat at highway. Or open up shroud or no shroud and cool at highway speeds and over heat at idle low speeds. Here is the mechanical fan I swap For the original. 6 blade 20”. The problem is the radiator is like 20” tall but the water pump center is not the center of the radiator. The pic with the fan on top of the aluminum shroud shows the size to the radiator core.
I will I have the electric fan and shroud out and putting the mechanical fan. It may be a few weeks have to travel for work for a while.
So you have similar results with that 6 blade 20" fan? In the pic it looks too far from the rad, it should be close.... 1" to 1.5" from the rad to be effective w/o a shroud. I have 7 blade fans on 2 of my GS's.... one is a fixed GM fan, the other is a clutch fan from 80's GM cars. No shroud on either, no overheat problems. I once had a flex fan with a shroud and it ran hot... poor fan design. The 1980's clutch fan setup I have (Regal V6 clutch with Caddy fan) has a lot of twist in the blades. I bet it moves a lot of air at slow speeds. Clutch allows it to slip on the highway for low drag. I'd highly recommend something similar... should be fairly easy to find in a junkyard. Fan design makes a difference!! Water pumps... std uses a 3 blade impeller, A/C versions use a 5 blade impeller to move more water. A/C setups also have different size pulleys to spin the water pump (and fan) faster. I still think your problem is not enough air flow at slow speed, but increasing water flow might be worth considering. A smaller water pump pulley would spin your fan a little faster for more air.
I used spacer so when installed it was about 1" away. I was showing the height of it where it is higher then the top of the radiator. What dia are you running on the fan and what is the height of the radiator core. Center of my water pump is about 2" higher then the center of the core. So I talked to another guy with a 60 with a aluminum radiator running the original 4 blade fan and no cooling issues. I am going to try the original 4 blade with the aluminum and no shroud to see what happens. Next I am going to pull the water pump to make sure the impeller is in the right position. I have a quote to install a 5 vane on it. He is thinking it may be a water flow issue. I can keep it cool at low speeds with the electric fan and the aluminum shroud but over heats at highway speed with that setup. Thanks
Devin posted a link to a great article on engine cooling in another thread, it's a good read, lots of tech info. https://www.enginebasics.com/Engine Basics Root Folder/Engine Cooling.html A couple of excerpts which apply to your situation: >>>> - IMPROVEMENT RULE # 1 -Anything you can do to increase the coolant flow rate, within limits described, will improve heat transfer and cooling performance. *** Going to the 5 vane water pump and/or changing the water pump pulley should increase your flow. -Improvement Rule #2- Anything you can do to improve airflow through the radiator core will help. Anything that blocks or slows airflow, either before or after the radiator, will hurt. *** Your A/C condenser obviously decreases your air flow. -IMPROVEMENT RULE- #7 Adding a row of tubes may help, but it may hurt by increasing cooling air restriction and reducing the coolant flow rate in the tubes. If the cooling airflow has been increased over the original installation, adding a row or two will probably help in this situation. Increasing the number of rows beyond 4 in a louvered fin core will almost always hurt. -IMPROVEMENT RULE- #8 Adding two rows of tubes without increasing the coolant flow rate (Bigger pump or turning the old pump faster) will probably reduce performance because of low coolant flow rate in the tubes. Reducing the tube size or going to dimple tubes may help. Increasing the coolant flow rate will surely help. <<<< And back to earlier discussion.... - is your vacuum advance working? If not, you have retarded timing at idle and low-load highway speed. - My blue '66 has a 22.5" x 19" high radiator core. It's narrower than the later 68-up GS's, making it somewhat of a challenge to keep cool. The late model clutch unit with 18" fan did wonders, even without a shroud. Welcome back!
What kind of car is this in? Some of these old cars just don't flow air very well through the engine compartment. (Edited - I see it's a 60 Buick. Same problems may apply.) I have just been through basically the same problems as you with my 49 Buick with 455 and have had similar problems with my 49 Chev/ 350SBC. Getting air through the radiator is only half of the equation. You must get air OUT of the engine compartment. With a 4 row radiator and electric fan, there is not air flow, in all likelihood. I had a 4 row Walker copper/brass radiator and Cooling Components fan. I ended up making a shroud and installing a 15" flex fan which cooled me down as long as I was movind. At a standstill, however, it would just keep getting hotter and hotter. I ended up with two small 5" puller fans in the top of my shroud and two 5" pushers in the inner fender to pull the hot air out. Also, if you have headers, you should wrap them. They generate a lot of heat in an engine compartment. Before doing any of this, make sure you have correct ignition timing and are not running too lean.
If you do not run enough total timing the motor will not make enough cylinder pressure to pump out all that heat it needed to at low engine speed, on top of that all the fuel the motor takes in will not get burned in the chambers, but in the exh manifolds or headers.
Ok sorry for the delay had lots of stuff going on. So set the advanced timing today at 30. Have a flex fan in and made sure it is setting about 1” from the radiator. Took it for a drive and did great at 55 mph. Stayed around 180. Drive through town at low speed and hit home and idled for a while and started to climb back up Over 225.
