Author Topic: 383 engine temperature  (Read 340 times)

Offline IroquoisPliskin

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383 engine temperature
« on: August 12, 2017 - 06:57:16 am »
Hi guys, I'm running a 383 engine in my 'cuda and usually my temperature gauge is reading like in the attached picture.
Recently I was cruising at around 65 mph at a sunny day and I noticed that the arrow moved slightly up into the lower corner of the center marking, which is more than what it reads usually but not that bad I guess.
But when I run the car at around 5500 rpm / 100 mph the reading moved to the upper section of the center marking (maybe like 80% of it). I guesss I haven't seen that high reading of that gauge before and I run that fast for just few minutes (I guess less than five), which is why I'd like to check the engine temperature by an infrared thermometer.
The question is what is the normal working area I should expect for my engine? And what is the critical temperature that should not be exceeded?
Except that: do you know what temperature the gauge markings are corresponding to?

When talking about the temperature, please make clear if your numbers are centigrade or Fahrenheit otherwise I might get confused 😀. Thanks!


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Offline ed-pv

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Re: 383 engine temperature
« Reply #1 on: August 12, 2017 - 07:48:44 am »
In my experience, the original gauges are getting to the age where their accuracy and reliability are in question.  I guess I should ask if your gauge is original or a rebuilt unit.  With the amount of money we spend on our engines these days, I always run a good aftermarket temp gauge and oil pressure gauge in tandem with the originals.  They have saved me more than a few times!

As far as normal operating range on your gauge, on my big block Mopars I run a 180 deg T-stat and on the stock gauge the needle pretty much stays in between the lower quarter of the gauge to just above the center of the gauge.  This correlates to 180 on the low end to 200 on the high end.  I have never seen the needle deflect as much as you describe even driving triple digits.  I live in Florida and it is REALLY HOT!

Hope this helps.

Offline chargerdon

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Re: 383 engine temperature
« Reply #2 on: August 12, 2017 - 08:00:00 am »
I believe the range is from 160 to 220 on the middle strip...   So long as it stays there your fine.   The final line is usually around 240 and that is in danger territory.   If you can drive 100 mph with 5500 rpm and not overheat...that's great !


Offline Racer57

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Re: 383 engine temperature
« Reply #3 on: August 12, 2017 - 10:05:16 am »
This is what the gauges for my 383 show. These were taken before it was fully warmed up. 185-190 is still only a fraction higher than whats shown.
« Last Edit: August 12, 2017 - 10:08:42 am by Racer57 »

Offline IroquoisPliskin

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Re: 383 engine temperature
« Reply #4 on: August 13, 2017 - 04:21:23 pm »
Thanks for the replies! I'll try to make the measurements soon and will let you know the results.


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Offline AARuFAST

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Re: 383 engine temperature
« Reply #5 on: August 13, 2017 - 07:35:10 pm »

Does your ride have a fan clutch?

My 383 does the same only goes up half way at high speed.

Other Cooling System Problems Affecting Fan Clutch Operation

Plugged radiator (inside or outside) can delay or eliminate fan clutch engagement

Partially opened thermostat does not allow full coolant flow to the radiator

Too much antifreeze concentration does not transfer heat as well as 50/50% mixture
Symptoms of Fan Clutch Problems


Poor cooling at low speed but good cooling at high speeds

Poor air conditioning at low speeds

No increase in fan noise when engine is hot
Symptoms of Radiator Problems

Poor cooling at high speeds

Good cooling at low speeds
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Offline IroquoisPliskin

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Re: 383 engine temperature
« Reply #6 on: August 16, 2017 - 09:24:59 am »
Hi guys,
I had an occassion to make some measurement yesterday.
When driving in the city or outside but with alternating speed like 30-60 mph my gauge reading and corresponding temperature measured by IR thermometer are as in attached pictures.


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Offline IroquoisPliskin

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Re: 383 engine temperature
« Reply #7 on: August 16, 2017 - 09:29:29 am »
When I drive speeds in the range 45-70 mph at constant speed for a longer time the gauge reading is a bit more than in the following pictures (a bit more than the center) but i wasn't able to catch the exact reading on the camera.


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Offline IroquoisPliskin

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Re: 383 engine temperature
« Reply #8 on: August 16, 2017 - 09:44:36 am »
If I go to higher speeds (90-100 mph) the needle goes into the upper corner of the center marking. It happens also sometimes when going the middle range spped constantly and stopping suddenly for a while (for example in case of traffic jam).

Well, what's your opinion? Do I have a cooling problem or not?
« Last Edit: August 16, 2017 - 09:48:13 am by IroquoisPliskin »


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Offline IroquoisPliskin

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Re: 383 engine temperature
« Reply #9 on: August 16, 2017 - 09:46:45 am »
Does your ride have a fan clutch?



How can I recognize if there is a fun clutch or not?

I think I have something like this installed (see attachement).
« Last Edit: August 16, 2017 - 10:10:22 am by IroquoisPliskin »


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Offline 73440

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Re: 383 engine temperature
« Reply #10 on: August 16, 2017 - 11:09:53 am »
Yep, that is the fan clutch, it should have resistance to turning when engine is off.
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Offline Racer57

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Re: 383 engine temperature
« Reply #11 on: August 16, 2017 - 06:02:02 pm »
From what I'm understanding the higher the sustained rpm the higher the temps get. Besides what others have said... do you have a shroud ? what size/condition of the radiator ? Ignition timing ? I'm now using a 750 carb which probably took 20+ degrees off my temps from the 650 I had.

Offline IroquoisPliskin

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Re: 383 engine temperature
« Reply #12 on: August 17, 2017 - 05:53:05 am »
Yep, that is the fan clutch, it should have resistance to turning when engine is off.

When pushing the fan blades I can feel resistance quite clearly and tha fan just moves like 1/10th of a full turn.

The radiator is the big one 26" radiator. I guess still the original one. Its condition makes a quite good impression when looking at it from the outside. The shroud is still installed.

I'm running a 600 (1405 Edelbrock) carburetor on it. I guess it's more likely to have a higher temperature at higher rpm but actually I expect the cooling system to be designed for keeping the engine at a certain working temperature independent on what speed you choose. If you compare to a modern car it's warming up to a certain temperature and stays there doesn't matter if you cruise in the city or you run high speeds on the highway.
The question is: how normal is the behaviour that I can observe in case of my 'cuda?
I'm wondering because for the last five years I never have seen the needle to go further than to the point in the picture (I actually was asking myself if the gauge is working at all).
I'm trying to find out if something is wrong with the cooling system or the behaviour is maybe related to the changes and fine tuning done during the last few years.
Of course a very important question to me is: Is the current status and the temperature range still healthy to the engine or is some action required at that point?


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Offline Racer57

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Re: 383 engine temperature
« Reply #13 on: August 17, 2017 - 09:11:30 am »
Check your timing.

My car came with a Eldebrock 600 and ran hot.  Switched to a Eldebrock 650 and it helped. Last Christmas someone had a Holly 750 double pump, dual feed, mechanical secondary on sale. Temps went down about 20 degrees and cars response went way up !!  Sounds better but mileage went from 13 to 10.

Offline chargerdon

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Re: 383 engine temperature
« Reply #14 on: August 17, 2017 - 03:48:37 pm »
Ok, first the carburetor being used should NOT affect the engine temperature,  assuming that it is providing the correct air/fuel ratio. 

Now, I believe that if your running lean, the engine will create more heat??  Richer less heat, but worse fuel economy fouling of plugs, etc.   I think??  But the radiator system and thermostat should still maintain whatever the thermostat calls for if not then the radiator and fan combo aren't big enough for your application.   If changing carbs then your obviously changing the air/fuel mixture. 

Back in the 60's and 70's the cooling capacity wasn't always up to the big engines heat capability.   Especially, when your running larger carbs without modifying the jets.   Remember, you can put on a bigger carb, which has jets designed for maximum air flow, but the engine doesnt change so typically the larger carb will run richer, and produce less heat, but, way worse gas economy, and very little extra power.   Heck i think the original 383's came with only a 500 cfm carb, so putting bigger carbs on can change the air/fuel ration negatively as far as heat output or vice versa.