Hello All,

I switched to electric fans becuase the mechanical fan would creep up to over 220 when the a/c was running in traffic in warm south florida. I have a new champion 4 row aluminum radiator with aluminum fan shroud they sell with two 12" SPAL-1522 Electric fans like the pic below. The temp while stopped is not bad at about 190 with both fans running but the temp creeps up above 200 while running.

I know that some shrouds have vent slots that are covered by rubber flaps so I'm not sure if that could be the issue. So I'm hoping someone has been down the road to save me some time. The voltage at the fans in idle is 13 volts so they should be running full RPM.

 

If your temperature creep is occurring during cruise then I would say yes the flaps are needed to allow sufficient airflow. If the fans are not on during cruise they may be a restriction to airflow. My shroud does have the air flaps and does very well in cruise with temps. Typically 180* or so up to 100* outside air temp.

in Florida you have humidity to deal with. Makes cooling less efficient.

may also want to check your timing. Are you using full manifold or ported vacuum for that. How much advance are you running? In cruise ported or manifold won’t matter at idle it will. Should have about 50-52* of total advance at cruise rpm.

 

I'm running 36 advance total with vacuum canister disconnected. I believe the advance vacuum is connected to manifold (so I have vacuum on the canister at idle).

 

On my 427 when the distributor's vacuum advance is disconnected the temp will continue to climb. It needs to be connected to the right vacuum source on the carburetor. The timing is critical because if your timing is too retarded it will make the engine run hotter as well. You want the vacuum advance working and a total timing of 36-36* but this depends on the engine and it's internal parts.

Be very sure that your engine compartment is well sealed and that all the air is being pulled throughthe radiator by the fans. The little rubber flaps keep the air going through the radiator when going slow and open when the airflow is higher. You need to have effective seals on the radiator to keep the air from flowing over the radiator versus going through the radiator and getting rid of the heat. In the really warm parts of the year my 1968 runs cooler without the front license plate and the headlights in the upright positions while driving. This allows the most air to get into the engine compartment. I am running a higher than normal compression ratio in my 427 which makes significantly more heat than normal.

One thing I always use on the 427 with 12.25-1 Compression is a bottle of Red Line Water Wetter as it really helps the engine stay cooler. The Water Wetter is a surfactant that allows the metal surfaces inside your engine to NOT have a layer of tiny bubbles on the metal surfaces inside the engine. Water Wetter allows the metal to transfer heat more effectively than just plain coolant. Regarding coolant, living in Florida you probably don't have a risk of freezing so you can run more water and less anti-freeze in your coolant. In Virginia I run 30% anti-freeze and 70% distilled water in my engine's coolant system. Anti-freeze does nothing to help your engine cooling, it lubricates the water pump and keeps the engine's coolant from freezing in the winter. Water is a much better heat transfer medium. Having a good radiator cap is also important as it keeps the pressure up inside the coolant system which allows it to get up to over 260* before boiling over.

Having a working overflow system is critical to keeping your engine cooler. If you don't have an overflow bottle that allows the coolant to expand and go into the overflow bottle then your expanded coolant gets dumped on the ground. It should be drawn back into your engine as it cools down. This prevents the radiator from getting a big volume of air into it which doesn't help your cooling system.

Be sure that your electric system is able to get full battery voltage to your electric cooling fans. This is where the right wire size is important. My two 11" SPAL fans are wired with 10 gauge wire to each of them. I also use a DeRale PWM Electric Fan Controller which starts the fans up at a pre-designated point at 50% speed and if the engine continues to go up the fans increase their speed. It is nice to not have 2 fans running at 100% speed from the time they turn on. Check your battery voltage when both fans are running and be sure it is still above 12.6 volts.

 

1971, 350, TH 400, 2.02 LT1 heads and cam, flat top pistons .030 over stock, Edelbrock Performer intake with a custom-built Holley 700 on top, and 100amp alternator. I'm running a Cold-Case radiator with a self-made shroud and two 12' fans that I took from some aircraft carrier size Chrysler product at pick & pull. I ended up putting a 160-degree thermostat in because it would go over 220 in traffic, and once it got hot it couldn't recover. My engine builder told me that I should expect the engine to run 15 to 20 degrees above the thermostat. He also told me to move the temp. sender from the head to the intake manifold, right near the thermostat housing, as it would give a more accurate reading of the fluid temp, so I did that too. My engine now averages around 185, but I haven't hooked up my AC yet.


Picture Taken 7/22/2022

 

a 50/50 mix of antifreeze and water raises boiling point to 223*f vs 212*f straight water. Under 14 psi pressure it is even higher about 262*f.
Antifreeze is also an “ anti-boil” type additive. Thus doing what the water wetter is also doing by delaying the onset of boiling. reducing or eliminating air bubbles in the system improving surface contact with the fluid and removing heat.

pure water is more efficient at removing heat if it doesn’t boil, It will however, boil sooner.

I don’t know off hand if water wetter delays the boiling point or just reduces the surface tension of water. Soap is a surfactant also. So is jet dry for dishes. Not sure you’d want either in your cooling system however.

 

Interesting posts on the use of surfactants in your cooling system. Food for thought.

https://www.pirate4x4.com/threads/so...wetter.359128/

 

I am surprised to hear that a coolant actually helps deter boiling as that is news to me. I am an Engineer and have spent many hours working on my very hot running L88 replica. The use of a Surfactant like soap can make a blooming mess of Bubbles. Water Wetter is an awesome product with decades of usage and plenty of positive experiences. It does reduce the operating temperature of most any normal water cooled engine. When a water cooled engine gets up to operating temperature little bubbles form along the walls of the engine's internal cooling surfaces and these inhibit the heat transfer process. When you put the water wetter in the engine there are no bubbles inside the engine and the transfer of heat becomes more effective. Normally you can see from 10 to 20* drop in operating temperature on our Corvette engines. I have used it in my 1988 C4 as well as my 1968, both have aluminum radiators which also helps cooling.

Many years ago I tried straight distilled water and then I added the water wetter and the difference was quite noticeable. My 12.25-1 compression 427 still likes to run hot during the summer months (Like NOW) so I have a Water/Methanol Injection system to help with the cooling and the lower octane fuels. The water helps reduce the combustion chamber temperatures and the methanol gives me the equivalent of 115 octane fuel. I use regular old windshield washer fluid in the system and it really helps the engine in the hot months. It is the easiest way to get the octane without buying racing fuel or other expensive materials.

Early on many years ago I switched my 427 to using a material called EVANS NPG which is a water-less coolant that is able to remove the heat fast enough to stop detonation from occurring. It was expensive to switch over but the stuff works great. It is now over 2 decades old and still working like a champ. The only bad side is that you can't put any water into it. If you have a leak you need to replenish it with more NPG and that stuff has gone up a lot in the past 2 decades. I have sent samples to Evans for them to analyze and it seems to be okay and working well.

Don't be so hesitant to try new ideas, the water wetter does really work and I have been very happy using it for a long time. There are other brands but I have always used the Red Line brand since I have experience with it. In my experience I use as little anti-freeze as I need to have some protection but don't need a lot here in Northern Virginia where it seldom gets anywhere near zero degree (F). All my vehicles run the 70/30 mixture to get the most effective cooling possible. My Liquid cooled Yamaha RZ-350 motorcycle also has NPG in the cooling system and it too has had it for close to 20 years as well. It works as well but is very expensive to fill a big block with it. I am not so sure the NPG is cost effective to use in a normal engine but for a hot running engine it cane make a big difference. There is something about a 427 BB running high compression that really makes it fun as well as fast! Today it sports a Holley Sniper EFI system that I am getting finished setting up as I retired my expensive Carburetor collection for once and all. I have five custom built carburetors all built for my 427. The 0-60 times are in the sub four second range with a 3.36 rear and the four speed.

 

what year car do you have? do you have the a good size ait dam to force the air into the radiator air box. Is that area completely sealed so that the air that goes in goes through the radiator and not around it. I have a single 16 inch fan with no flaps and my big block runs cooler than my small block did, but that little mouse had some horsepower behind it. are they both spinning in the correct direction? If the temp goes up with the fans running something isnt correct.

how does it run in traffic going slow, how about cruise on the highway?

 

and is your coolant clear and the proper color or is it rusty. If it isnt a nice bright green anymore you should get your lock and system flushed

 

Thanks for the input. The radiator is new and I added a gallon of antifreeze with water for the rest. It's a 1980 so it has a nice air dam to push up the air so I don't think that's the issue but I'll take a look.

 

make sure to check all the seals that block the top of the hood to radiator gap and around the radiator to the radiator support. Its good to know so you can eliminate that. then make sure the fans are spinning correctly, that they are coming on at 185 or 195 and dont shut off until below your lowest on setting. Your temp switches could be bad. Do you have a bypass switch to turn on the fans when you want?