69 Dart cooling questions

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skep419

skep419

5.9 Magnum 4 speed afficionado
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I have a 69 Dart with a 425 hp 360. I bought a summit aluminum radiator the same size as the stock 318 radiator except for the lower hose outlet. I had the brackets welded on so it would bolt in the factory location. Well this was about six years ago and now I am more interested in function over form.

I drive the car street strip and it over heats on the really hot days. I have new coolant and a 160 stat, new mech pump, flex fan with shroud, and a pusher on the front.

I have been reading that the pusher if not the same as the puller makes matters worse.

QUESTION- The radiator I have measures around 19 tall and 17.5 wide between the tanks. Would I be better off selling it and buying a bigger one from the junkyard.
QUESTION 2- I bought the electric fan from summit and not sure what is puts out but it wont fit between the rad and the pump (I think 16" s blade).

Is anybody else running a similar set up? What are you using for fans/radiators.

Should I buy a low pro electric water pump and try to use the fan I have as a puller? Or buy a different radiator that is wider and try to find a dual fan set up?
 
If it were mine I'd install a 180 fail safe stat and purchase the Mopar Perf viscous fan from Mancini or Summitt. That is what took care of my overheating problem. It pulls lots of air even on those 100+ days here. You need the 180 to keep the water in the radiator longer to allow it to cool. Also throw in a bottle of Wetter Water. It helped my puller rig to run cooler.
 
Cooling is all about surface area (of the radiator) and airflow (usually the fan at lower vehicle speeds).

I assume you have the two row summit aluminum radiator which has about 1" tubes, so a 2" thick core, yes?

First, since your current radiator is cooling acceptably except for the hottest days, I would try a new fan first. A pusher is not quite as good as a puller type fan. I went through this years back on my 66 Charger bracket car and after trying several inexpensive fans, I learned the lesson and bought a Spal electric puller fan. I put them on all the customers cars now and would not consider anything else. They draw a lot of current, but move a lot of air and that's what the fan is all about!

Your radiator is a little small and if you have the room (or are willing to trim the front core support), I would recommend a large radiator, but the fan would me my first change. Get a puller and mount it and see how it cools. Even if you decide the upgrade the radiator, you will still use the puller fan, so you will not be out any $$$

Another area is sealing the radiator to the core support and the hood to the core support. You do not want any air getting around the front support unless it travels through the radiator! My secret weapon for sealing those spots is garage door lower seal strip material from your local home center. About 1.5" wide, made of rubber and can be easily trimmed to fit.

Hope that helps!
 
John426 said:
Cooling is all about surface area (of the radiator) and airflow (usually the fan at lower vehicle speeds).

I assume you have the two row summit aluminum radiator which has about 1" tubes, so a 2" thick core, yes?

First, since your current radiator is cooling acceptably except for the hottest days, I would try a new fan first. A pusher is not quite as good as a puller type fan. I went through this years back on my 66 Charger bracket car and after trying several inexpensive fans, I learned the lesson and bought a Spal electric puller fan. I put them on all the customers cars now and would not consider anything else. They draw a lot of current, but move a lot of air and that's what the fan is all about!

Your radiator is a little small and if you have the room (or are willing to trim the front core support), I would recommend a large radiator, but the fan would me my first change. Get a puller and mount it and see how it cools. Even if you decide the upgrade the radiator, you will still use the puller fan, so you will not be out any $$$

Another area is sealing the radiator to the core support and the hood to the core support. You do not want any air getting around the front support unless it travels through the radiator! My secret weapon for sealing those spots is garage door lower seal strip material from your local home center. About 1.5" wide, made of rubber and can be easily trimmed to fit.

Hope that helps!
Click to expand...

yes it is a two row.

so what your saying is go with a spal electric puller fan because they clear the water pump. How big of alternator am I going to need I think mine is a 72amp mopar.

What about shrouds?

any pics of where the rubber sealer installed.
 
It is all about the surface area as stated. Do you know how thick the cores are? I bought one from wizzardcooling.com out of new york and so far I cant get the car over 155 degrees idling in the garage for an hour. I have a high flow 160 t-stat and high flow 8 blade water pump. Here is a pix of it. Looks and functions great. By the way my cores are 11/4 inch thick x 2

015.JPG
 
Check for hot and cold spots on radiator after car is warmed up. Maybe radiator is bad. Check lower and upper hose to see if both are hot after car is run. You should not be overheating with a radiator of that size.
 
I like the idea of the electric fan (more power) how much cfm do I need.
There is a 16" on ebay straight blade puller with 2350cfm?
 
Looks like an awesome set up to me to Slappy. I can't under stand why it would overheating. skep419 are you running an underdrive pulley setup?
 
jefflock said:
Looks like an awesome set up to me to Slappy. I can't under stand why it would overheating. skep419 are you running an underdrive pulley setup?
Click to expand...
yep underdrive set up. Im thinking the pusher fan i have in the front needs to go. I've been told its doing more harm than good.
 
I'd do like jefflock says & try a 180 thermostat if you haven't already. Sometimes a 160 can let the water through so soon that the radiator doesn't have a chance to do it's job. I'd also get rid of the pusher (it could be blocking airflow) & switch to the Mopar viscous fan setup. And I agree that that radiator & shroud should be adequate.
 
'64 Cuda said:
I'd do like jefflock says & try a 180 thermostat if you haven't already. Sometimes a 160 can let the water through so soon that the radiator doesn't have a chance to do it's job. I'd also get rid of the pusher (it could be blocking airflow) & switch to the Mopar viscous fan setup. And I agree that that radiator & shroud should be adequate.
Click to expand...

I'm going to swap the stat and buy a good electric puller fan. The viscous fan is 115 bucks I'm hoping to find an electric fan that clears the mechanical water pump and pulls some killer cfm for around the same price. What cfm would you say I need to get out of a 16" fan to keep her cool.
 
I`m not a fan of flex fans. I`ve had a few and they never seemed to cool well. I`d get a good viscous fan of the largest diameter that`ll fit inside the shroud. Mopar`s unit is good and like Jefflock and 64cuda said, replace the 160 thermostat with something a little hotter. A water pump for an A/C car may help. A good flush of the system and a refill with fresh coolant can`t hurt either.
 
16 inch fan seems a little small as well. My car takes a stock 18 inch. I guess I threw in the 160 due to overheating all summer. 180 should be sufficiant. Although I do like not worrying about overheating now.
 
Lots of good advice here and I suppose some of your Ultimate decision will depend on what you intend for the car and how mush $$$ you want to invest.

Since you drive the car on the street, a case can be made for the mechanical fan. Since you already have a mechanical (albeit a flex fan) why not try removing the pusher first and see what happens? Its an easy test and doesn't cost anything!

Regarding the t-stat, 160 vs 180 will not change how long the water is in the radiator, it will only change the temp at which the t-stat is wide open. The size of the opening will be the same, which means the restriction to the flow of water will be the same, just 20 degrees hotter. Having no t-stat might cause water to move through too quick, but I doubt it - that problem is just not seen very often with Mopars.

If you do decide to go the electric fan route, just remember that the cfm ratings by the manufacture are... well... impossible to verify. About the only rating that I've ever been able to rely on is the amperage draw. The simple math here is: the higher the amp draw of the motor, the more work it is doing and the more air it is moving. Now that is a very oversimplified gross statement, but it is more reliable than the cfm ratings often stamped on electric fans.

Next up is packaging. As you have no doubt noticed, your mechanical water pump is the closest object to the radiator - just remember that there is no law requiring the electric fan to be in line with the water pump! I like to offset the electric fans towards the bottom of the radiator on the theory that the top portion may sometimes have no water and I want as much airflow over the water filled section as is possible.

BTW - I am in the middle of building a Hemi powered Dart for a customer and we had a 3" thick radiator custom made to fit. We planned to use a pair of high-output SPAL 10" fans and when they came in - they where too thick to fit!! And we had even done a mockup - just shows no one is perfect (chuckle), some of us a little less than others (!!). Now we are going to change to a pair of regular output 11" fans (SPAL does not have a regular output 10" fan - drat!) Oh yeah - in addition to having an automatic transmission (and needing a trans cooler) the Hemi Dart also has A/C !!

And now back to the cooling bit, final component is a shroud. I am a big proponent of getting all the air to move through the radiator first and then to get it to move through the fan only. To the first aim, seal the radiator to the core support and seal the hood to the core support - the factory used a very simple rubber hood seal and they often work the best, even on fiberglass hoods. When you replace the OEM radiator with something non stock, there will often be a gap around the opening. I use some flat rubber garage door seal to fill the gap (hold it in place with the radiator mounting tabs / bolts).

Now that all the air that comes in the grille is only going through the radiator, I build a shroud around the fan. This is really more important with a mechanical fan as the electric ones often have a shroud built in, but I like to block errant airflow except for the fan opening. I do add some additional holes in the shroud for airflow at higher pressures (zipping down the highway at 75 mph etc.) and they can be louvers or dimple die holes. I will get some pictures of the Dart's cooling setup once the new fans arrive (sheepish grin!).

Here is a pic of the radiator sitting in place. We made a lower mount that cradles the lower core support frame rail brace and an upper mount that bolts to the original core support upper bar. You can't see the A/C compressor as it is on the passenger side of the engine mounted below the alternator (sort of where the original fuel pump was).

Dec10200816.jpg


And here is one of the garage door seal I spoke of. You can just see the Black seal mounted between the core support and the aluminum radiator on this Challenger.

Aug18200803.jpg


Hope that helps!
 
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