Can an engine run too cool? - Chevelle Tech
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post #1 of 49 (permalink) Old Apr 5th, 20, 3:04 PM Thread Starter
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Rob
 
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Can an engine run too cool?

Iím having a tough time dialing in my quadrajet. Itís a 396 stroked to a 440. Iíve followed all the cooling threads thru the years and have a 160 degree thermostat in, there 1/8 holes drilled, a high flow impeller on the original water pump rebuilt by the Dutchman in Oregon, a 4 core radiator, shroud, clutch fan, sealed off the sides of the shroud to the radiator. Iíve got a gauge package which Iím sure is not real accurate but the temp indicator never gets to the first bar- under any conditions.

Hereís my stupid question, is it possible to run too cool? Hereís why I ask. I canít seem to dial in my Sean Murphy quadrajet. Itís set up perfectly, it has great manners, I have Autolite 3924í s for plugs- theyíre in a good heat range and I canít seem to keep them from a slight soot appearance.

I just took a 100 mile cruise, 50 street, 50 highway. 3:73 in the rear so itís spinning good on the highway. I have no black smoke on a flick or a flooring of the throttle. I stopped to fill it up- Iím in So Cal and itís 65 degrees. I can touch the radiator, I can touch the manifolds for a moment, itís very cool under the hood. Would going to a 180 degree thermostat be better? Should I go to the next plug up in heat range?

Iím running a 72 main, 48 b rods, I set the float at .375 from the top as I was getting a wet gasket on carb- that worked. I have an AC pump on with a regulator set at 6 lbs. still running rich as evidenced by the plugs.

Plugs looked great before I converted to a 4 speed from an automatic. Might be something there too? Would love any suggestions and input. Rob
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post #2 of 49 (permalink) Old Apr 5th, 20, 3:10 PM
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Re: Can an engine run too cool?

I have had a few that ran cold like under 140 unless I stuck a piece of cardboard in front of the radiator or just a plastic sack or a couple blue paper towels you get at the gas station.

Winters here I need to block the radiator.
Try that first and see if you can get it to 160 or 190.
If that does not clear it up then step up the heat range of the spark plugs.
Clean the spark plugs before you set out on the next trial run. Or at least one of them to get a fresh reading
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post #3 of 49 (permalink) Old Apr 5th, 20, 3:31 PM
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Why Quadrajet ?
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post #4 of 49 (permalink) Old Apr 5th, 20, 3:34 PM Thread Starter
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Rob
 
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Re: Can an engine run too cool?

Original one to the car with an automatic. 7028210
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post #5 of 49 (permalink) Old Apr 5th, 20, 3:37 PM
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Only change is auto to 4 speed ?

Are you lugging car ?

Why not put a Holley on for driving, save Q for car shows ?
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post #6 of 49 (permalink) Old Apr 5th, 20, 3:41 PM
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Re: Can an engine run too cool?

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Originally Posted by Reelysalty View Post
Why Quadrajet ?
Quadrajets can run great! Why not a Q-Jet?

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post #7 of 49 (permalink) Old Apr 5th, 20, 3:45 PM
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Re: Can an engine run too cool?

Change that 160 degree thermostat for a 180 and see if that helps.
It's an easy thing to try.
I use a Milodon High Flow 180 thermostat and the rest of my cooling system is very similar to how you describe yours and mine works very well,no running too hot or too cold issues here !!
The Milodon High Flow does not require the holes drilled in them.
Guy
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post #8 of 49 (permalink) Old Apr 5th, 20, 3:50 PM Thread Starter
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Re: Can an engine run too cool?

Quadrajet once set up is pretty reliable. Just canít seem to get it right here. Only change was auto to manual. Strike that, I did add the rebuilt high flow impeller water pump..

Last edited by RHinkel764; Apr 5th, 20 at 4:05 PM. Reason: Addition
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post #9 of 49 (permalink) Old Apr 5th, 20, 4:39 PM
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Re: Can an engine run too cool?

You're gonna get soot with it running that cool, carb may be fine? like has been said, install 180 stat.
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post #10 of 49 (permalink) Old Apr 5th, 20, 5:12 PM
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Re: Can an engine run too cool?

My SBC with a 160 never opens and a 180 will not either.. small holes drilled in them.
I suppose if I quit drilling them.

My Nova I could drive 8 miles down the highway with NO cooling fans on before it got to 160.
I have a fan on my 57 and I have went 100+ miles down the highway at 3000 rpm and never got off 140 temps.
My temp gauge is in the thermostat housing. This is below 60 degree days.

I have stuck my thermostat in a pan of water on the stove and turned the fire on under it to see when it opens.
A good thing to do with all new thermostats. I cook every one of them and found 2 bad ones that were new.
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post #11 of 49 (permalink) Old Apr 5th, 20, 5:36 PM
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Re: Can an engine run too cool?

Quote:
Originally Posted by RHinkel764 View Post
Itís set up perfectly, it has great manners
So what is the problem ??

Quote:
Originally Posted by RHinkel764 View Post
I canít seem to keep them from a slight soot appearance.
If you never looked at them would you think there was anything wrong ? Even the slightest bit of idling time can start to soot up a plug. I think you are worrying about nothing. The only way to get a real accurate reading from a spark plug is to make a WOT pass and shut of the engine clean and coast to the side of the road and pull a plug.

In my opinion it is better to run an engine as hot as possible within reason. It will be more efficient. That is why newer vehicles all run at much higher temps. But . . I dont think it going to affect your plugs any.
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post #12 of 49 (permalink) Old Apr 5th, 20, 6:01 PM
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Re: Can an engine run too cool?

My 4.3L V-6 boat has a 160 degree stat.
My daily drivers have either 180-190 degree stats.
My diesel has a 200 degree stat.
The Chevelles do have 180 degree stats.

Each engine had different requirements.
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post #13 of 49 (permalink) Old Apr 5th, 20, 6:07 PM
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Re: Can an engine run too cool?

Yes an engine can run too cool, you need the heat to dissipate the moisture that builds through condensation inside the engine and in the oil. Fuel does not vaporize well at low temps causing combustion issues. Run a 180* thermostat and all those issues go away.

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post #14 of 49 (permalink) Old Apr 5th, 20, 6:15 PM
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Quote:
Originally Posted by jeff swisher View Post
My SBC with a 160 never opens and a 180 will not either.. small holes drilled in them.
I suppose if I quit drilling them.

My Nova I could drive 8 miles down the highway with NO cooling fans on before it got to 160.
I have a fan on my 57 and I have went 100+ miles down the highway at 3000 rpm and never got off 140 temps.
My temp gauge is in the thermostat housing. This is below 60 degree days.

I have stuck my thermostat in a pan of water on the stove and turned the fire on under it to see when it opens.
A good thing to do with all new thermostats. I cook every one of them and found 2 bad ones that were new.
👍 I use 160 in 2 cars (sometimes 180 for some heat in winter). Not unusual to drive 10 miles in 85’ weather w/o fan coming on (set about 175) in 383.

There’s a reason engines are dynoed at 160.
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post #15 of 49 (permalink) Old Apr 5th, 20, 7:14 PM
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Re: Can an engine run too cool?

Please post both timing specs initial, vacuum advance degrees, along with full manifold or ported, total, and comp ratio, cam DEGREES,m don't care about lift, and what materials the block and heads are.

YES, engines can, and do run too cold when set up/tuning advice isn't correct for the applications.

Cast iron block, cast iron heads, 180 degrees, cast iron block, aluminum heads, 192/195 degrees. Sounds like there aren't any problems in the cooling system setup.

What reason is it that dictates an engine be "dyno'd" at 160 deg/F. engine temperature, please?
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