Hot at highway speeds

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Check your lower hose, maybe it's collapsing some at higher speeds, got a spring it? Just something easy to rule out.
 
spl440 said:
My 67 Dart used to run hotter above 70mph, moded a early Dakota air dam to the lower bumper with the opening in the Dakota air dam help forcing air into the lower part of the rad, no more issues at speed.
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Smart boy. Actually the opening is there to reduce wind resistance a little, that's all. What an air dam does under the bumper is push air forward back into the grill and into the radiator. It also helps to block the area between the front of the K frame and the rear of the front valance panel, as well as blocking all the holes and sealing up and cracks and crevices in the radiator support. All of this forces air to go through the one hole it's supposed to and through the radiator.
 
RustyRatRod said:
Smart boy. Actually the opening is there to reduce wind resistance a little, that's all. What an air dam does under the bumper is push air forward back into the grill and into the radiator. It also helps to block the area between the front of the K frame and the rear of the front valance panel, as well as blocking all the holes and sealing up and cracks and crevices in the radiator support. All of this forces air to go through the one hole it's supposed to and through the radiator.
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Thanks Rusty, means a lot.
 
$1,400 radiator? Whoah! I'd run a full fan shroud. I was told that at higher speeds, there is a tendency for air to stagnate at the front of a cars radiator as the fan cant pull it through fast enough. (look at a Daytona/Superbirds small inlet in front) a fan shroud is supposed to assist in this (could be BS but Ill pass it along for you to decide) try a teaspoon of Calgon dishwasher detergent in the radiator, it acts as a wetting agent, making it have more contact area with the cylinders. 210 is nothing for a motor.
 
Well, the GV reduces your engine rpm to 78 %. So working the math the rpm with the GV musta bin 3000 x .78 = 2340.. Now, going the other way ; 3000/2340=1.28, or a 28% increase in revoutions per minute. Your engine is firing 28% more times per minute. And every extra time it fires it creates an extra bit of heat .Thats part 1.
As the rpm goes up, so does internal friction.Thats more heat.Part2
The oil pump is working harder and the crank is beating up the oil ; More heat. Part3
The higher crank speed is spinning up the TC, which spins up the transmission oilpump which just pumps the oil around in a circle and dumps it back into the pan. More heat going to the rad cooler.PT4
So where does all this heat go? Well,some is re-radiated through the iron walls of all the engine bits, and some out the tranny case, and some goes out the exhaust. But a great deal of this extra heat ends up in the rad.
And when the rad cant get rid of it fast enough, the coolant temp starts to rise.Eventually the rising liquid temp finds a new equilibrium point at which the rad can shed the heat fast enough,if the engine lives through it.
 
pishta said:
$1,400 radiator? Whoah!.
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Sort of, It's a truly custom radiator with twin fans, billet recovery tank and wiring harness. Still expensive as hell but no one makes a radiator like this one, much less one that mounts like this one.



AJ/FormS said:
Well, the GV reduces your engine rpm to 78 %. So working the math the rpm with the GV musta bin 3000 x .78 = 2340.. Now, going the other way ; 3000/2340=1.28, or a 28% increase in revoutions per minute.
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That math is spot on
 
spl440 said:
My 67 Dart used to run hotter above 70mph, moded a early Dakota air dam to the lower bumper with the opening in the Dakota air dam help forcing air into the lower part of the rad, no more issues at speed.
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That's exactly what my engine guy told me to do. This is the first time I've actually seen someone mold a newer air dam to an old car. Really doesn't look all that bad.
 
clinteg said:
That's exactly what my engine guy told me to do. This is the first time I've actually seen someone mold a newer air dam to an old car. Really doesn't look all that bad.
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Hard to see in the picture, but there is an opening in the air dam with a panel below that I attached to the lower rad support, so it does channel the air into the lower part of the rad behind the bumper. "DART67" has a post when he did it to his BB 67 Convertible.
 

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We did the air dam on spl440's Dart first. He is the one that came up with the idea of using the Dakota air dam

Then we did one on my dart.

Here is the link to how we did it.

http://www.forabodiesonly.com/mopar/showpost.php?p=1969871218&postcount=6

Here is the link to the complete post:

http://www.forabodiesonly.com/mopar/showthread.php?p=1969871218#post1969871218


The air dam helps a great deal.

The thing that made the "BIGGEST" improvement on fixing my "over heating" troubles was to "RE-Instal" the factory hood to core support seal.
This seal is way more important then anyone thinks.

It blocks and keeps the heat from the engine bay from being drawn back over the top of the core support and recycled through the radiator and increasing the coolant temp.

It is a very viscous heat cycle without the seal.


On a final note, high temps at highway speeds is most often caused by not enough air flow through the radiator.

The air dam should be a big help in that regard.
Herb
 
The one thing I didn't see covered was the thermostat.

What kind? What degree rating? If you have a Hi volume WP, you NEED a hi flow thermostat. They open WITH the flow of water, not against like Stant brand does.

When you are pushing that much RPM, you are increasing volume(and in turn increase pressure) tremendously. With that being said, regular T stats will be pushed shut.

Not running a thermostat on the street is a bad idea. The cooling system works on an exchange basis. It needs the thermostat as a "door" to open and close. This allows the coolant in the rad to stay in as long as possible to have as much heat dissipated as possible.
 
Remember, hot at cruise/highway speed is waterflow. Hot at idle/low speed is airflow.
 
redfastback said:
Not sure I see where your going.....
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Since the car does not overheat at slow speed, radiator is cooling the engine with pump speed and airflow through radiator. Since it is not cooling at higher rpm and higher speed, makes more heat to cool, air flow through radiator not enough, because of air going around nose of car instead of through radiator. that is why in my case the lower air dam helped funnel the lower air that was not being used to go through the radiator for more airflow.
 
Well, I am going to agree to disagree. I see the problem more with water flow. When I ran my hot rod shop, I saw this problem alot. Usually the cooling system was not planned out..

But I guess he will figure out what he thinks is best....
 
redfastback said:
The one thing I didn't see covered was the thermostat.

What kind? What degree rating? If you have a Hi volume WP, you NEED a hi flow thermostat. They open WITH the flow of water, not against like Stant brand does.

When you are pushing that much RPM, you are increasing volume(and in turn increase pressure) tremendously. With that being said, regular T stats will be pushed shut.

Not running a thermostat on the street is a bad idea. The cooling system works on an exchange basis. It needs the thermostat as a "door" to open and close. This allows the coolant in the rad to stay in as long as possible to have as much heat dissipated as possible.
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What thermostat would you recommend?

Having similar issues.
Running a FlowKooler pump.
 
Run Milodon or Mr Gasket 180*. They are both hi flow t-stats. 180* because street cars operate the best between 170-190* & heat dissipation also is best between these temps.
 
I always use a "fails open" thermostat,, saves a nasty overheat, and a long walk or a tow bill when/if it fails..
 
FYI.... both the milodon 16406 & the mr gasket 4367 are fail open. They are both "balance sleeve" style which fail open if they ever fail.
I have installed over 200 of these thermostats in customer's cars and cant recall a single failure.
 
A little info found digging around. Some of the reasons I bought that Robertshaw in the ebay link above.


" The 330 series was their hi-performance line (330-160 & 330-180) that fit many GM and Ford engines. The 330 series had a 1.5" hole when it was open versus about a 3/4" hole for a standard stat. "

It is a balanced flow stat and fails open, also.

They are not easy to find. Summit and FlowKooler are both out of stock.

TX Dart and I were discussing your post and both think the thermostat being pushed closed could be part or all of my issue. Thanks for the insight. Will post back after install.


Edit: Looking at the Milodon and Mr Gasket, I don't see much difference. Looks like the same design. Probably the only differences are where it's made (US,Mexico,or China) and whether or not it has bypass holes. I have read some Mr Gaskets are repacked Robertshaws.
 
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