Cooling questions/suggestions

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Pumpkinduster

Pumpkinduster

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Hey all I am just looking to pick some brains here.
I have a 74 Duster with a mild built 318. The motor has been fully worked over from ground up with about 300 miles on it total. I am bored .30 over, block decked, 302 heads, comp cam Xtreme Energy 224/230, Summit long tube headers, Edlebrock performer RPM intake, and an Edlebrock 1405 4bbl carb.

Cooling system has been upgraded to 3 row aluminum radiator by Champion cooling with an aluminum shroud and dual 10in fans (currently on with ignition), the cap is a 16lbs cap. High flow water pump installed yesterday as well as a 160 high flow thermostat. I am testing distilled water with 10-15% coolant. But ultimately I am still getting/ having cooling issues.

Today I let it warm up to 160 and can see some coolant flow in the radiator. At an idle it got to about 170ish which I expected since it is 85 out and the pavement is hot.
As soon as I start creating more heat (throttle) the temp goes up, so I took it for a test drive. I went about 5 miles averaging about 45-50 mph. Temp climbed to about 180 and held for about a mile then anytime I gave it a little more gas the temp just keeps climbing. I eventually made it about 4 miles before I pulled over because the temp started hitting 205 and I was getting some vapor lock. (I have a full EFI conversion for the winter project) So i parked in the shade for about 10 minutes and popped the hood to let some heat expel then fired it up and finished the drive. The temp when starting it was about 199 and on the rest of the drive it dropped to about 197 until I hit my driveway 203.

I haven't checked it at cruising speeds yet just because it is supposed to be 100 out today so I don't feel the need to push it.

But is the accumulation of the heat under the hood (Headers) causing a lot of this issue or is it temp climbing solely from the internals getting that hot?
 
So it's doing all this at low speed and stop and go? You said "no cruising speed" so I have to assume so. It's those bullshitter fans. Put a real fan on it like a Mopar viscous fan. There are FAR better radiator options, too. Two BIG rows of tubes are FAR more efficient than three small ones. You need some cruise time though to verify it.
 
RustyRatRod said:
So it's doing all this at low speed and stop and go? You said "no cruising speed" so I have to assume so. It's those bullshitter fans. Put a real fan on it like a Mopar viscous fan. There are FAR better radiator options, too. Two BIG rows of tubes are FAR more efficient than three small ones. You need some cruise time though to verify it.
Click to expand...

Currently I cant replace the fans without replacing the radiator because there would be no clearance for it, but that's not in the budget since I just upgraded all this less then a year ago lol.

I cant agree with the fan statement though. The fans pull a strong amount of air through the radiator when on so not sure how changing to a clutched fan would make any improvements. Can you explain how it would improve it?
 
Pumpkinduster said:
Currently I cant replace the fans without replacing the radiator because there would be no clearance for it, but that's not in the budget since I just upgraded all this less then a year ago lol.

I cant agree with the fan statement though. The fans pull a strong amount of air through the radiator when on so not sure how changing to a clutched fan would make any improvements. Can you explain how it would improve it?
Click to expand...

You need about 4000 CFM of air flow for a mild to moderate HP build. Sounds like you got it figured out. Have fun with it.
 
Sounds like your "mild build" " fully worked" 318 runs just fine.
The purpose of the pressurized cooling system. 16 lbs. is to raise the boiling point of the coolant.
212° with straight water at sea level. Straight water with no cap.
Factory thermostat is 190 °.That is the temp that it opens to allow coolant to pass into the radiator, not what temp the car is running at.
Fans should be wired thru a thermostat control, just like modern cars, as speeds above 40 mph get no benefit from any fan. More air is forced through the core than a fan can pull or push at speeds above that.
Modern fuels have less octane and generate higher temps compared to the fues of the 60's. One reason that the compression ratios had to be lowered. Modified engines/tunes tend to run hotter than stock. Surprise?
Gauges don't show temps but only ranges from C to H because different applications run at different actual temperatures and postingg numbers would just confuse people about what was "normal".
Just like this posting. What is normal for your particular engine build combination. It won't be published anywhere as it isn't a tested combnation. All factory engine/car combinations have a factory baseline and they are different for different years, makes, models. This info is in the Factory Service Manuals.
 
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MoparLeo said:
Sounds like your "mild build" " fully worked" 318 runs just fine.
The purpose of the pressurized cooling system. 16 lbs. is to raise the boiling point of the coolant.
212° with straight water at sea level. Straight water with no cap.
Factory thermostat is 190 °.That is the temp that it opens to allow coolant to pass into the radiator, not what temp the car is running at.
Fans should be wired thru a thermostat control, just like modern cars, as speeds above 40 mph get no benefit from any fan. More air is forced through the core than a fan can pull or push at speeds above that.
Modern fuels have less octane and generate higher temps compared to the fues of the 60's. One reason that the compression ratios had to be lowered. Modified engines/tunes tend to run hotter than stock. Surprise?
Gauges don't show temps but only ranges from C to H because different applications run at different actual temperatures and postingg numbers would just confuse people about what was "normal".
Just like this posting. What is normal for your particular engine build combination. It won't be published anywhere as it isn't a tyested combnation. All factory engine/car combinations have a factory baseline and they are different for different years, makes, models. This info is in the Factory Service Manuals.
Click to expand...

Thank you for that info and that is good to know. I completely agree with the temp sensor and that is getting all tied in with the EFI conversion over the winter. So if I understand you correctly I may not actually be having any issues unless my water temp is rising above boiling? I do need to get it on a cruise that lets me run it at a consistent speed above 40 mph for longer then just a couple minutes, but I will wait until the weekend when the temps come back down a little. Supposed to be 104 tomorrow.
 
RustyRatRod said:
You need about 4000 CFM of air flow for a mild to moderate HP build. Sounds like you got it figured out. Have fun with it.
Click to expand...

I can completely see where I am under on the CFMs. 4000 cfm is a high goal at least with the electric fans, I believe most I have seen out of a single 16" is 3000cfms. What if hypothetically I was to run a 16" at 3000cfms pulling and one pushing. Do you think that would be be any benefit or would that cause to much obstructions to the air flow through the radiator?
 
A pressurised temp of over 212 ° is not necessarily running too hot.
Actual boiling point temp could be as high as 260 ° depending on altitude and coolant/water ratio.
You can only "push" so much air through a funnel.
There is a reason that a garden hose is only 5/8" in diameter as oppesed to a 6" firehose. At the same "pressure" one obviously flows much more "voluime"
Again fans are an obstruction above 40 mph.
Can only flow so much air based on area.
Also might check how lean your car may be running. Tune can also have a big effect on operationg temperature.
 
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Add another "I bought a super cool aluminum radiator with super cool electric fans and my car overheats" post

The two 10" fans and the "shroud" are blocking more airflow than they are providing.

I guarantee you will have heat issues on the interstate.

Pull the fans and shroud off. Put even a (and I hate to say it) flex fan and 80 percent of your cooling issues are gone

If you have worked yourself into a corner with that super cool aluminum radiator, sell it to someone else and get a stock type brass / copper with stock fan whether that is thermostatically controlled or fixed, be sure it is 7 blades. 5 on a thermostatically controlled might work.

The point of the fan is to move air through the radiator.

The point of a shroud is to assist in the fan moving air through the radiator at idel or slow speeds, at 30 to 40 and above the shroud only blocks airflow. A properly engineered one will not have much effect at speed but the super cool ones that are basically flat to the back of the radiator only block air flow.

Do some math... Length of your core times height of your core, that's the square inches of your core. 17x22=374 sq in

Now take 10" diameter fan hole A =πR^2
3.1415926 times 5 (hole diameter devided by 2) squared
3.1415926x25 = 78.5 sq in ( one hole)

Two holes total 157sq in opening
157/374= .419

This means that about 1/2 of your radiator has no airflow through it. Your trying to cool a 318 with a radiator for a Toyota Corolla from the 80s.


The Chrysler engineers figured out how to cool a 440 in a 69 dart, maybe they know something. Use what the factory manufactured for the application and don't have issues.


RANT OVER!
 
Too Lean?
My new 383 build consistently overheated while cruising a few years ago.
A sharp (older) Mopar mechanic figured out my new Edelbrock carb was too lean. He actually rebuilt the "new" carb to get the adjustment needed. Now it doesn't run hot and is much more responsive.
 
Joey4speed said:
Too Lean?
My new 383 build consistently overheated while cruising a few years ago.
A sharp (older) Mopar mechanic figured out my new Edelbrock carb was too lean. He actually rebuilt the "new" carb to get the adjustment needed. Now it doesn't run hot and is much more responsive.
Click to expand...

I have thought about that as well. I am going to the Holley Sniper EFI so that will change this Fall/Winter season. The car only has one more car show to drive to about 5 miles away then I can start the conversion.
 
Dana67Dart said:
Add another "I bought a super cool aluminum radiator with super cool electric fans and my car overheats" post

The two 10" fans and the "shroud" are blocking more airflow than they are providing.

I guarantee you will have heat issues on the interstate.

Pull the fans and shroud off. Put even a (and I hate to say it) flex fan and 80 percent of your cooling issues are gone

If you have worked yourself into a corner with that super cool aluminum radiator, sell it to someone else and get a stock type brass / copper with stock fan whether that is thermostatically controlled or fixed, be sure it is 7 blades. 5 on a thermostatically controlled might work.

The point of the fan is to move air through the radiator.

The point of a shroud is to assist in the fan moving air through the radiator at idel or slow speeds, at 30 to 40 and above the shroud only blocks airflow. A properly engineered one will not have much effect at speed but the super cool ones that are basically flat to the back of the radiator only block air flow.

Do some math... Length of your core times height of your core, that's the square inches of your core. 17x22=374 sq in

Now take 10" diameter fan hole A =πR^2
3.1415926 times 5 (hole diameter devided by 2) squared
3.1415926x25 = 78.5 sq in ( one hole)

Two holes total 157sq in opening
157/374= .419

This means that about 1/2 of your radiator has no airflow through it. Your trying to cool a 318 with a radiator for a Toyota Corolla from the 80s.


The Chrysler engineers figured out how to cool a 440 in a 69 dart, maybe they know something. Use what the factory manufactured for the application and don't have issues.


RANT OVER!
Click to expand...

I originally had dual 12" fans that where mounted directly to the radiator and the issue was still present. But that was before I added the high flow pump and thermostat. The only reason I went with a shroud was I guess poor advice in another post. I completely understand that shroud would be preventing full air flow so when on the hwy it probably wouldn't help.
 
Why are you out of room for a mechanical fan. You’ve got something wrong. There should be plenty of room for a mechanical fan on that.
 
But before you have a melt down; Set your timing with the Vcan to 46*@2600, and then put the carb on the fast idle step, closest to 2600rpm.
Now leave the hood up, with the fans going full-blast.
And wait.
If the temp stays below 210 you can make this combo work.
Next, close the hood; if the temp stays below 210*, it is already working.
This is an extreme test. There is no harder test for the cooling system than this; except if the engine was racing.
If it works with the hood closed;
then OPEN the hood.
From now on, if you drive it, you cannot go WOT, because I have no way of knowing what your PowerTiming will be. Remember no WOT.

Next I would add more timing ...... 4* for 50*@2600 and repeat.
If the temp goes down, I would add 3* for 53*@2600 and repeat.
If the temp goes down, I would add 3* for 56*@2600 and stop; 56 is plenty

But if at any time the temp goes up, kick the fast idle off , and pull some timing out until she cools off. then shut her off. If she won't cool, just spray a water mist on the rad.
Now;
you have seen the power of timing to control your heat. Try it again with the hood closed this time. If you have trouble, the very FIRST thing I would do is give that carburator some fresh cold air and then retest. When the carb is sucking hot underhood air, it like a runaway nuclear reactor.

Once that is done, it's time for a roadtest. Remember to give her the max-timing that you earlier determined, and drive it in the range of 30/35 mph at 2600rpm.
If you have trouble on the roadtest, blame it on one of two things;
1) the air cannot get thru the rad fast enough, or
2) the air is getting thru the rad fast enough but is not able to exit the underhood fast enough.If the hot air cannot get out, then fresh air cannot get in, and that Hot air may be at a higher pressure than the incoming cold air. So go home and take the hood off then repeat the test.
>>If still gets hot;
First try it at 40 mph.
If now cooling, try a faster roadspeed, and with less rpm, etc. If all good; yur done, your system works with the hood off.
>>If same overheating; Shut the engine off and let her cool under 160. Pull the electric fans and shrouding off and toss 'em into the trunk.
You are now set up for a ram-air efficiency test. The rad is fully exposed to the wind, The hood is off. The cruise timing is set to some fantastic number over 46*@2600, so all systems are a go.
So start her up and move it out. You need to find a roadspeed close to or over 30/35mph that is near to 2600rpm (roadgear is not important) and just drive it for a couple of miles. STAY off the Power and OUT of traffic.
If this works then we know your cooling system will work. Repeat the test with the hood on. If still good; then you just need a more powerful fan and a working shroud.

Ok so that's how I would attack this problem.
My system runs at a rock-solid 205 to 207, with an ancient radiator out of a 73 to 76, 318 Dart with A/C..... even the patches have patches. But I have a honking big fan on a honking big HD thermostatic clutch.

BTW
the thermostat sets he MINIMUM operating temperature. Anytime the temp FALLS below the set-point, the Stat will begin to close. The stat has NOTHING to do with the temp running OVER the minimum.
The maximum temp is not set by the size of the rad either.
The max is set by the ability of the system to shed heat. @Dana67Dart is on the right track. If at over 30/35 mph the air thru the rad is restricted by the electric fans being there, then ram-air cannot do the job by itself.
 
AJ/FormS said:
But before you have a melt down; Set your timing with the Vcan to 46*@2600, and then put the carb on the fast idle step, closest to 2600rpm.
Now leave the hood up, with the fans going full-blast.
And wait.
If the temp stays below 210 you can make this combo work.
Next, close the hood; if the temp stays below 210*, it is already working.
This is an extreme test. There is no harder test for the cooling system than this; except if the engine was racing.
If it works with the hood closed;
then OPEN the hood.
From now on, if you drive it, you cannot go WOT, because I have no way of knowing what your PowerTiming will be. Remember no WOT.

Next I would add more timing ...... 4* for 50*@2600 and repeat.
If the temp goes down, I would add 3* for 53*@2600 and repeat.
If the temp goes down, I would add 3* for 56*@2600 and stop; 56 is plenty

But if at any time the temp goes up, kick the fast idle off , and pull some timing out until she cools off. then shut her off. If she won't cool, just spray a water mist on the rad.
Now;
you have seen the power of timing to control your heat. Try it again with the hood closed this time. If you have trouble, the very FIRST thing I would do is give that carburator some fresh cold air and then retest. When the carb is sucking hot underhood air, it like a runaway nuclear reactor.

Once that is done, it's time for a roadtest. Remember to give her the max-timing that you earlier determined, and drive it in the range of 30/35 mph at 2600rpm.
If you have trouble on the roadtest, blame it on one of two things;
1) the air cannot get thru the rad fast enough, or
2) the air is getting thru the rad fast enough but is not able to exit the underhood fast enough.If the hot air cannot get out, then fresh air cannot get in, and that Hot air may be at a higher pressure than the incoming cold air. So go home and take the hood off then repeat the test.
>>If still gets hot;
First try it at 40 mph.
If now cooling, try a faster roadspeed, and with less rpm, etc. If all good; yur done, your system works with the hood off.
>>If same overheating; Shut the engine off and let her cool under 160. Pull the electric fans and shrouding off and toss 'em into the trunk.
You are now set up for a ram-air efficiency test. The rad is fully exposed to the wind, The hood is off. The cruise timing is set to some fantastic number over 46*@2600, so all systems are a go.
So start her up and move it out. You need to find a roadspeed close to or over 30/35mph that is near to 2600rpm (roadgear is not important) and just drive it for a couple of miles. STAY off the Power and OUT of traffic.
If this works then we know your cooling system will work. Repeat the test with the hood on. If still good; then you just need a more powerful fan and a working shroud.

Ok so that's how I would attack this problem.
My system runs at a rock-solid 205 to 207, with an ancient radiator out of a 73 to 76, 318 Dart with A/C..... even the patches have patches. But I have a honking big fan on a honking big HD thermostatic clutch.

BTW
the thermostat sets he MINIMUM operating temperature. Anytime the temp FALLS below the set-point, the Stat will begin to close. The stat has NOTHING to do with the temp running OVER the minimum.
The maximum temp is not set by the size of the rad either.
The max is set by the ability of the system to shed heat. @Dana67Dart is on the right track. If at over 30/35 mph the air thru the rad is restricted by the electric fans being there, then ram-air cannot do the job by itself.
Click to expand...

I will give this a shot, can you clairify what you are referring to “set your timing with the Vcan”?
 
448Scamp said:
Why are you out of room for a mechanical fan. You’ve got something wrong. There should be plenty of room for a mechanical fan on that.
Click to expand...

He has a three row new style aluminum radiator. Those are notorious for having wider than necessary cores AND having the brackets attached so that the whole radiator is closer to the engine. There've been several on here like that.
 
Pumpkinduster said:
I will give this a shot, can you clairify what you are referring to “set your timing with the Vcan”?
Click to expand...
Just leave the Vacuum Advance can hose alone, this is for setting the cruise timing and the Vcan must be working. To do this, you will need either; a dial-back advance timing lite or with a regular lite, you would need a timing tape glued onto your balancer/damper.
Don't be scared of what sounds like a really big number. Your engine, at 2200rpm will like timing easily as high as 35/40 degrees. It might even like nearly that much at idle. At idle, this will not hurt the engine.
 
Rusty makes a good point in #17.
If you have one of those, you must seal up the rad to the front core support so that all the air that hits it is forced to go thru it. And so your super-duper fans cannot suck hot underhood air over the top/around the sides/ or up thru the bottom.. The brackets should block the sides OK, but you gotta seal the bottom and top.
 
AJ/FormS said:
Rusty makes a good point in #17.
If you have one of those, you must seal up the rad to the front core support so that all the air that hits it is forced to go thru it. And so your super-duper fans cannot suck hot underhood air over the top/around the sides/ or up thru the bottom.. The brackets should block the sides OK, but you gotta seal the bottom and top.
Click to expand...

I will double check the bottom, but I have sealed the upper portion already.
 
Some basics first. These are simple, cost free [ of dollars ] only takes some of your time. Not in any order.
[1] Ign timing. Where is the initial timing set & is your centri curve advancing in the dist? Retarded ign causes overheating.
[2] Lean mixture causes hot running. If your carb has a choke, try this. Engine idling, close the choke blade slowly until the engine note changes. Open the blade slightly & wire the blade in this position. This will richen the mixture. Test drive & see if it runs cooler.
[3] Hi flow stat. If it has the three upper legs of stainless steel, it is a present from Beijing. I have had many of these stick closed, fail to open. They need to be removed & some ATF dribbled into the cup to lubricate the internal rubber seal. Check with a saucepan on the stove to make sure it opens. Once tested like this, they seem to work ok afterwards. Original American made [ scarce now ] have the three legs in brass.
[4] As others have suggested, remove the toy fans. You can put them above the fire place, next to the pic of Biden....Use a good mechanical 18" fan.


As others have
 
RustyRatRod said:
He has a three row new style aluminum radiator. Those are notorious for having wider than necessary cores AND having the brackets attached so that the whole radiator is closer to the engine. There've been several on here like that.
Click to expand...


I understand. But I looked up the core thickness for his 3 core Champion and it’s 3/16 thicker than my Cold Case 2 core. And I have to run about 1.375 inches of spacer to get the fan up to the radiator. I’m confused as to where all the room went. I’d like to see some pictures of what the OP has.
 
448Scamp said:
I understand. But I looked up the core thickness for his 3 core Champion and it’s 3/16 thicker than my Cold Case 2 core. And I have to run about 1.375 inches of spacer to get the fan up to the radiator. I’m confused as to where all the room went. I’d like to see some pictures of what the OP has.
Click to expand...

Me too.....we ALL would I imagine. LOL I forget who it was on here but somebody had one where the brackets were almost a solid INCH forward of the tanks. Just stupid stuff like that. I'm like you not understanding, because until Vixen, I've always used factory radiators, either reconditioned or recored. I had a 65 Valiant radiator recored to a 4 core years ago and STILL had room for the Mopar viscous fan package. I've seen people argue me down that a clutch fan won't cool as good as some....but I don't think they've ever used one. lol
 
I have listed my set up previously, with part numbers, no problems with my 418, hood on or off is the same. See this issue so many times. Research before buying.
 
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