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  #1  
Old 06-19-2007, 08:23 AM
Coyote Jack Coyote Jack is offline
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Help Radiator Options?

I have a 72 Demon with a 360/727 combo with 400+ HP. I have 4:10's out back. This is primarily a street car. I am using the radiator that came with the original car that had a 318. It is the small radiator and although there is nothing wrong with it, it is just not up to the job. When cruising at highway speeds the temp goes up to 205 and it is still only 70 degrees here on the average day and I know it's going to get much hotter. It stays at 180 when idling. Getting a universal aluminum from Summit or Jegs is not an option as the shipping across the border is a killer.
So here is my question.
What options have others used to get enough cooling into a setup like this? Radiators from other vehicles is what I am thinking.

Jack
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  #2  
Old 06-19-2007, 09:24 AM
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dwc43 dwc43 is offline
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Biggrin

205 to 210 is just fine. Just make sure nothing is clogging the rad you have. Make sure to run a shroud with the fan properly spaced. Also check your timming and make sure your not running to lean on the carb jets. IT should be just fine.
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  #3  
Old 06-19-2007, 10:02 AM
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rumblefish360 rumblefish360 is offline
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Rebuilding the rad. is one option. Making sure the rest is up to par is the starting point.
Good coolent balance. 50/50 min.
Free flowing core in the rad.
pressure cap working and hoding correct
A viscous fan or good electric fan. Not the stock fan.
And what DW said.
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Old 06-19-2007, 10:13 AM
Coyote Jack Coyote Jack is offline
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There are a few things here that I am thinking about. The fact that it can sit and idle for long periods leads me to believe that I have good air flow from my fan, (18" flex fan, 7 or 8 blade). The second is that this is a 35 year old rad that is not bad looking but may have blocked passages. It does not leak. The other is that I can get the bigger rad that came in the 340's/360's of the time period very cheap new.

Jack
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Old 06-19-2007, 10:18 AM
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dwc43 dwc43 is offline
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Biggrin

You can do that if you want to, but it's just wasted money. Your not overheating at all. Your right where it should be. I know I would not want it to run less than 195 cause you loose effeciency. Just fine tune what you have and it should be fine and make sure your rad is clean. A good cleaning would cost hardly nothing compared to the cost of a new rad.
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Old 06-19-2007, 10:59 AM
turbododge turbododge is offline
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If he is getting 205 at 70 degrees outside, he is going to be in trouble when it gets to 95 degrees, or if he has a full load of passengers, or if he has a big tailwind. It is just cutting it too close. I believe that you should pretty much always be running on the thermostat, except in extreme circunstances.

He is correct in saying that his airflow from fan and pulleys is good, because he stays cool at idle. Since the problem is at speed, a shroud is not really going to help. All that is left is to increase the capacity of the radiator. Make sure all the fins are straight, get it tanked. If it is a two or 3 core, you could have it recored to 4 cores, although it usually doesn't help much once you get to 3 cores.

You could add an air dam below the valance to reduce the pressure under the car and get more airflow.

Check your jetting to make sure you are not lean, with those gears you are running a lot of rpm for the load, and it is very easy to go lean.

As above, you are running a lot of rpm for the load, so you may need to take a little timing out of it under those conditions.

As always, be sure you have a spring in the lower hose, so it doesn't collapse.
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  #7  
Old 06-19-2007, 02:29 PM
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rumblefish360 rumblefish360 is offline
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Rid yourself of that flex fan and finish the favor off with a viscous fan.
A 4 re-coreing would be very nice if it is shot.
Try a low temp stat.
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  #8  
Old 06-20-2007, 04:26 PM
dgc333 dgc333 is offline
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Quote:
Originally Posted by Coyote Jack View Post
There are a few things here that I am thinking about. The fact that it can sit and idle for long periods leads me to believe that I have good air flow from my fan, (18" flex fan, 7 or 8 blade). The second is that this is a 35 year old rad that is not bad looking but may have blocked passages. It does not leak. The other is that I can get the bigger rad that came in the 340's/360's of the time period very cheap new.

Jack
Jack, I have the v8 heavy duty, AC replacement radiator form Advance Auto (#433528) in my car. This is the radiator listed for the 340 cars to.

My 360 is not making 400HP but it's close; moving, stopped, hot or cold the engine warms up to the point the t-stat opens then the temp is constant and the guage does not move higher (except for when I threw a belt and didn't notice the amp guage discharging ).

I think it was about $160 two years ago so it was a no brainer for me.
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  #9  
Old 06-20-2007, 07:24 PM
cudabob496 cudabob496 is offline
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So what is your extra shipping costs. They may be worth it as an aluminum is the way to go.
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  #10  
Old 06-21-2007, 01:55 AM
krazykuda krazykuda is offline
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Keep this in mind when choosing a radiator - area gives you more improvement than thickness.

If you can add length and/or width without modifying/cutting the front core support it gives you more benefit.

Thickness adds capacity, but restricts airflow. I'm not saying don't do this, just keep this in mind when choosing a radiator.

I agree with rumblefish with tossing the flex fan and going to viscous.

Try a 160° thermostat.

USE A FAN SHROUD. This is very important to help the fan pull air through the radiator. Your fan should be half in the shroud and half out.

Try replacing the water pump with one for an A/C car as they sometimes have more capacity. Ask the parts guy if the part numbers are the same or different for A/C or no A/C for your car.

I have a 68 Cuda 340 S with 3.91. It has a stock recored 3 core radiator, original shroud, 160 thermostat and does not have any problems with running hot.
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  #11  
Old 06-21-2007, 10:56 AM
daredevil daredevil is offline
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What about a water wetter additive? They claim to lower temps 10 to 20 degrees.
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  #12  
Old 06-21-2007, 03:12 PM
turbododge turbododge is offline
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My opinions on these suggestions from krazycuda.

Quote:
I agree with rumblefish with tossing the flex fan and going to viscous
This probably won't have a big effect as the problem is at speed, when the fan is not doing much, except maybe restricting airflow. Will a viscous restrict less, maybe, maybe not

Quote:
Try a 160° thermostat.
All a 160* stat will do is delay how long it takes to overheat, it will not effect max temp acheived

Quote:
USE A FAN SHROUD. This is very important to help the fan pull air through the radiator. Your fan should be half in the shroud and half out.
A shroud usually will make this type of overheating worse, as there will be more restriction to the aiflow from the motion of the car. Shrouds help at idle and low speeds

Quote:
Try replacing the water pump with one for an A/C car as they sometimes have more capacity. Ask the parts guy if the part numbers are the same or different for A/C or no A/C for your car
This is backwards. AC pumps on mopars are lower capacity at the same speed. They make up that capacity by spinning them faster on AC cars. An AC pump on standard pulleys will move way less water than a non-AC pump]
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  #13  
Old 06-21-2007, 04:15 PM
345Dart 345Dart is offline
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Jack
I'm running one of these from Don at FBO and small viscos 5 blade. If you are getting one - get the one with the tank - wish I had.

I can send a pic of my installation if you like - fits A-body opening
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  #14  
Old 07-03-2007, 03:00 PM
Coyote Jack Coyote Jack is offline
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I went with the stock 340 rad. It is 7 inches wider than what I had and that makes a world of difference. The car now heats up to 180 and stays put at highway speeds. Problem solved.

Jack
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