Question...what is the normal running temp for a 1972 340

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krazykuda said:
it happens on new cars. that's why they pack the cooling modules with seals to keep the air from going around the radiator and condenser.

If the fan is spinning too slow, it can block the airflow at highway speeds also.
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But we are talking about an old A-Body, the radiator is wide open. No way is the air going to miss the radiator or go around it at 65 mph without significant modification to the grille area or the radiator being physically blocked (packed full of mud and bugs, covered with a plastic bag, cardboard or other large road debris).

The fan is also on the backside of the airflow so the radiator won't care what speed it's spinning when the car is traveling 65.
 
Everything is original as far as the air flow through the grill with the exception of a trans cooler which is a radiator looking cooler that lets air flow through it also and only covers 12'' x maybe 10" of radiator ....... and that sets 6" in front of radiator allowing air to flow between the two ......also had this issue before trans cooler. other than that is open. Also it does have a 7 blade fan .....
 
John Morrow said:
What is Diagnosis ?
Everyone keeps saying ...Bigger Radiator ....If I buy one I plan on at least trying to get a bigger 3 core, but I keep asking myself ......surely it was not running hot in 1972 with the original 2 core. I have had the car for 16 years used to drive it to the Nationals 10 + years ago .. about 4 hours from my house, 55-60 mph on highway, after about 3 hours would always notice it leaning to the hotter side.... nothing to scare me, I just blamed it on the 391 gears. I started trailering to Columbus, the short 30-40 minutes from hotel to show never noticed anything.
Last year I drove it back to Indy for a Good Guys show and the following weekend to Monster Mopar again 55-60 with 323, gears took my time ....again it ran a little on the hot side enough to make me a little nervous this time .......now I cannot seem to drive 45 min. at 55 and driving 65 70 for 10-15 min puts the temp gauge up to 230-240 before I get off the highway and it starts cooling down. Looks like Radiator is next ......after that I guess Ill pull the motor knock out all freeze plugs and have a look around.
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I think you have answered you own question.
The longer you have owned the car the hotter it seems to run.
I bet you have some corrosion build up that is restricting water flow.
I would knock and easy to replace soft plug out and see if the block is getting clogged up.
Another thing when you mix antifreeze are you using tap water or distilled water?
Tap water will contribute to corrosion over time, and distilled water does not and it is only $1.00 a gallon.
 
sireland67 said:
I think you have answered you own question.
The longer you have owned the car the hotter it seems to run.
I bet you have some corrosion build up that is restricting water flow.
I would knock and easy to replace soft plug out and see if the block is getting clogged up.
Another thing when you mix antifreeze are you using tap water or distilled water?
Tap water will contribute to corrosion over time, and distilled water does not and it is only $1.00 a gallon.
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Thanks .....starting to lean that way .......new radiator is still in the works ...just so I know its going to be good for a few more years to come ......
 
sireland67 said:
I think you have answered you own question.
The longer you have owned the car the hotter it seems to run.
I bet you have some corrosion build up that is restricting water flow.
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I think you are on the right path here. A good flushing of the system may solve the problem.

In the end, the radiator may need replaced (being that it's old and has already been worked over), but I like to at least try to fix a problem without tossing a fist full of cash at a car.

We haven't mentioned tuning. Something like being lean on the top end (65-70 mph with 3.91 gears should have the RPMs up a bit) could cause excessive heat.
 
make sure the a/c condenser isnt filled up with bugs and debris and the fins arent all smashed on it especially since its in front of the rad if it gets clogged up with stuff it will block air going to the rad
 
1968FormulaS340 said:
We haven't mentioned tuning. Something like being lean on the top end (65-70 mph with 3.91 gears should have the RPMs up a bit) could cause excessive heat.
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Very good point,, late timing, or lean would create more heat,, so check your timing,, and pull a coupla plugs, and read them..

hope it helps.
 
ohiocowboy1277 said:
make sure the a/c condenser isnt filled up with bugs and debris and the fins arent all smashed on it especially since its in front of the rad if it gets clogged up with stuff it will block air going to the rad
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A/C condenser has been removed just incase it was the reason. ....it did change anything.
 
If you do find out the cooling system is clogged when you get it cleaned out, run distilled water with your coolant. That's really what's supposed to be run anyway but nobody ever does.
 
inertia said:
Next time it gets hot,, use your heat gun to measure the temps all across the rad., you're looking for cool areas,, I know it's been rodded, humor me...

I'm also curious about the temp difference between upper and lower hose, while hot and running..
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Temp difference between upper and lower hose is about 10* ...about 180-170 same across the tank. motor reads as the gauges read 225-230 +

Messed with the Timing didn't seem to change nothing .......still looking into that .... ...I'm thinking trying the flush with some sort of additive it try and break up any calcium that might be in the block .....next Ill just pull the motor when the weather changes and go through it. .......still going to try the Radiator first !!!! Maybe I'm overlooking something,,,,,,I dunno :banghead:
 
I once put a newer fan on an older 454 motor home and didn't notice they changed the fan rotation at some point on BB chevys. So my fan was actually pushing air backwards through the radiator. It was cool around town and at idle but as soon as you hit 40mph or so the wind speed would cancel out the fan and it would overheat. I felt pretty dumb but luckily noticed it just 7 miles form home on a 1000+ mile trip.

This couldn't be your problem but reminded me of one of my famous dohs!
 
If you've got another vehicle around, get it up to temp, and see what the temp diff is on it's upper and lower hoses,.
 
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